def find_tail_bias(fun_ibiasn, nch_db, vtail, vgs_min, vgs_max, seg_tail_min,
itarg):
seg_tail_iter = BinaryIterator(seg_tail_min, None, step=2)
while seg_tail_iter.has_next():
seg_tail = seg_tail_iter.get_next()
def fun_zero(vgs):
narg = nch_db.get_fun_arg(vgs=vgs, vds=vtail, vbs=0)
return fun_ibiasn(narg) * seg_tail - itarg
if fun_zero(vgs_min) > 0:
# smallest possible current > itarg
seg_tail_iter.down()
if fun_zero(vgs_max) < 0:
# largest possible current < itarg
seg_tail_iter.up()
else:
vbias = sciopt.brentq(fun_zero, vgs_min, vgs_max) # type: float
seg_tail_iter.save_info(vbias)
seg_tail_iter.down()
seg_tail = seg_tail_iter.get_last_save()
vbias = seg_tail_iter.get_last_save_info()
return seg_tail, vbias
def find_edge_size(self, # type: ResTech
grid, # type: RoutingGrid
core_info, # type: Dict[str, Any]
is_lr_edge, # type: bool
params, # type: Dict[str, Any]
blk1, # type: int
max_blk_ext, # type: int
):
# type: (...) -> Tuple[int, Dict[str, Any]]
"""Compute resistor edge size that meets DRC rules.
Calculate edge dimension (width for LR edge, height for TB edge) that meets DRC rules
Parameters
----------
grid : RoutingGrid
the RoutingGrid object.
core_info : Dict[str, Any]
core layout information dictionary.
is_lr_edge : bool
True if this is left/right edge, False if this is top/bottom edge.
params : Dict[str, Any]
the resistor parameters dictionary.
blk1 : int
dimension1 block size in resolution units.
max_blk_ext : int
maximum number of blocks we can extend by.
Returns
-------
n1 : int
edge length in dimension 1 as number of blocks.
layout_info : Dict[str, Any]
the edge layout information dictionary.
"""
bin_iter = BinaryIterator(1, max_blk_ext + 2)
ans = None
while bin_iter.has_next():
n1 = bin_iter.get_next()
if is_lr_edge:
tmp = self.get_lr_edge_info(grid, core_info, n1 * blk1, **params)
else:
tmp = self.get_tb_edge_info(grid, core_info, n1 * blk1, **params)
if tmp is None:
bin_iter.up()
else:
ans = tmp
bin_iter.save()
bin_iter.down()
if ans is None:
raise ValueError('failed to find DRC clean core with maximum %d '
'additional block pitches.' % max_blk_ext)
return bin_iter.get_last_save(), ans
async def _search_helper(
self,
w: int,
seg_min: int,
seg_max: Optional[int],
data_min: Optional[Any],
data_max: Optional[Any],
) -> Tuple[Any, int, int, int]:
# first, binary search on segments without changing width
bin_iter = BinaryIterator(seg_min,
seg_max,
search_step=self._search_step)
bval_min = bval_max = None
if data_max is not None:
bval_max = self.get_bin_search_info(data_max)[0]
if data_min is not None:
bval_min = self.get_bin_search_info(data_min)[0]
bin_iter.set_current(seg_min)
bin_iter.up(val=bval_min)
elif seg_max is not None and data_max is not None:
bin_iter.set_current(seg_max)
bin_iter.down(val=bval_max)
bounds = [[seg_min, bval_min, data_min], [seg_max, bval_max, data_max]]
while bin_iter.has_next():
cur_seg = bin_iter.get_next()
cur_data = await self.get_data(cur_seg, w)
cur_bval, up = self.get_bin_search_info(cur_data)
if up:
bounds[0][0] = cur_seg
bounds[0][1] = cur_bval
bounds[0][2] = cur_data
bin_iter.up(val=cur_bval)
else:
bounds[1][0] = cur_seg
bounds[1][1] = cur_bval
bounds[1][2] = cur_data
bin_iter.down(val=cur_bval)
if bounds[1][1] is None:
idx = 0
seg_min = seg_max = bounds[0][0]
elif bounds[0][1] is None:
idx = 1
seg_min = seg_max = bounds[1][0]
else:
idx = int(abs(bounds[1][1]) < abs(bounds[0][1]))
seg_min = bounds[0][0]
seg_max = bounds[1][0]
opt_bnd = bounds[idx]
opt_seg = opt_bnd[0]
opt_data = opt_bnd[2]
a_min = seg_min * w
a_max = seg_max * w
return opt_data, opt_seg, a_min, a_max
async def _upsize_gate_for_del_spec(
self,
dut_params: Dict[str, Any],
tspec: float,
seg_cur: int,
is_nand: bool,
tbm: CombLogicTimingTB,
seg_even: bool,
spec_type: str,
seg_max: Optional[int] = None,
) -> Tuple[int, np.ndarray, np.ndarray]:
if spec_type != 'delay' and spec_type != 'slope':
raise ValueError("spec_type must be either 'delay' or 'slope'.")
bin_iter = BinaryIterator(seg_cur, seg_max, step=1 << seg_even)
while bin_iter.has_next():
new_seg = bin_iter.get_next()
dut_params['params'][
'seg_nand' if is_nand else 'seg_nor'] = new_seg
dut = await self.async_new_dut('nand_nor_upsize', STDCellWrapper,
dut_params)
sim_results = await self.async_simulate_tbm_obj(
'nand_nor_upsize_sim', dut, tbm, self._tb_params)
if spec_type == 'slope':
ans = CombLogicTimingTB.get_output_trf(
sim_results.data, tbm.specs,
'nand_pu' if is_nand else 'nor_pd')
gate_tr, gate_tf = ans
else:
ans = CombLogicTimingTB.get_output_delay(
sim_results.data,
tbm.specs,
'in',
'nand_pu' if is_nand else 'nor_pd',
out_invert=True)
gate_tf, gate_tr = ans
trf_metric = gate_tf if is_nand else gate_tr
if np.max(trf_metric) > tspec:
bin_iter.up(np.max(trf_metric) - tspec)
else:
bin_iter.down(np.max(trf_metric) - tspec)
bin_iter.save_info((new_seg, gate_tr, gate_tf))
info = bin_iter.get_last_save_info()
if info is None:
gate_str = "nand" if is_nand else "nor"
err_str = f'Could not find a size for {gate_str} to meet the target spec of {tspec}.'
self.error(err_str)
seg, tr, tf = info
return seg, tr, tf
def interp1d_no_nan(
tvec: np.ndarray,
yvec: np.ndarray) -> Callable[[Union[float, np.ndarray]], np.ndarray]:
tsize = len(tvec)
if np.isnan(tvec[-1]):
bin_iter = BinaryIterator(1, tsize + 1)
while bin_iter.has_next():
delta = bin_iter.get_next()
if np.isnan(tvec[tsize - delta]):
bin_iter.save()
bin_iter.up()
else:
bin_iter.down()
tsize -= bin_iter.get_last_save()
return interp1d(tvec[:tsize], yvec[:tsize], assume_sorted=True, copy=False)
def get_max_track_width(self,
layer_id: int,
num_tracks: int,
tot_space: int,
half_end_space: bool = False) -> int:
"""Compute maximum track width and space that satisfies DRC rule.
Given available number of tracks and numbers of tracks needed, returns
the maximum possible track width.
Parameters
----------
layer_id : int
the track layer ID.
num_tracks : int
number of tracks to draw.
tot_space : int
available number of tracks.
half_end_space : bool
True if end spaces can be half of minimum spacing. This is true if you're
these tracks will be repeated, or there are no adjacent tracks.
Returns
-------
tr_w : int
track width.
"""
bin_iter = BinaryIterator(1, None)
while bin_iter.has_next():
tr_w = bin_iter.get_next()
tr_sep = self.get_sep_tracks(layer_id, tr_w, tr_w)
if half_end_space:
used_tracks = tr_sep * num_tracks
else:
used_tracks = tr_sep * (num_tracks -
1) + 2 * self.get_sep_tracks(
layer_id, tr_w, 1)
if used_tracks > tot_space:
bin_iter.down()
else:
bin_iter.save()
bin_iter.up()
opt_w = bin_iter.get_last_save()
return opt_w
def helper_fun(
w_test: int, h_test: int, binfo: Optional[ArrayLayInfo], wc: int,
hc: int, opt_a: int, iterator: BinaryIterator
) -> Tuple[Optional[ArrayLayInfo], int, int, int]:
cur_area = w_test * h_test
if cur_area >= opt_a:
# this point can't beat current optimum
iterator.down()
return binfo, wc, hc, opt_a
else:
cur_info = self.get_blk_info(conn_layer, w_test, h_test, nx,
ny, **kwargs)
if cur_info is None:
iterator.up()
return binfo, wc, hc, opt_a
else:
# found new optimum
iterator.down()
return cur_info, w_test, h_test, cur_area
def design_tail(specs, itarg, seg_min):
"""Find smallest tail transistor that biases the differential amplifier."""
db = specs['in_db']
sim_env = specs['sim_env']
vds = specs['vdst_min']
in_type = specs['in_type']
if in_type == 'pch':
vds *= -1
ib_fun = db.get_function('ibias', env=sim_env)
vgs_idx = db.get_fun_arg_index('vgs')
vgs_min, vgs_max = ib_fun.get_input_range(vgs_idx)
# binary search on number of fingers.
seg_tail_iter = BinaryIterator(seg_min, None, step=2)
while seg_tail_iter.has_next():
seg_tail = seg_tail_iter.get_next()
def fun_zero(vgs):
farg = db.get_fun_arg(vgs=vgs, vds=vds, vbs=0)
return ib_fun(farg) * seg_tail - itarg
val_min = fun_zero(vgs_min)
val_max = fun_zero(vgs_max)
if val_min > 0 and val_max > 0:
# smallest possible current > itarg
seg_tail_iter.down()
elif val_min < 0 and val_max < 0:
# largest possbile current < itarg
seg_tail_iter.up()
else:
vbias = sciopt.brentq(fun_zero, vgs_min, vgs_max) # type: float
seg_tail_iter.save_info(vbias)
seg_tail_iter.down()
seg_tail = seg_tail_iter.get_last_save()
if seg_tail is None:
raise ValueError('No solution for tail.')
vgs_opt = seg_tail_iter.get_last_save_info()
tail_op = db.query(vbs=0, vds=vds, vgs=vgs_opt)
return seg_tail, tail_op
def check_density_rule_edge(cls, n0, s0, s1, area):
# type: (int, int, int, int) -> int
"""Compute edge block dimension from density spec.
Given edge width or height (as dimension 0), find the missing dimension (dimension 1)
such that density rule is met.
Parameters
----------
n0 : int
edge length in dimension 0 as number of blocks.
s0 : int
dimension 0 block length in resolution units.
s1 : int
dimension 1 block length in resolution units.
area : int
the resistor area in the edge block that should be used for density spec.
In resolution units squared.
Returns
-------
n1 : int
edge length in dimension 1 as number of blocks.
"""
density = cls.get_res_density()
# convert to float so we're doing floating point comparison
area = float(area)
bin_iter = BinaryIterator(1, None)
a0 = n0 * s0 * s1
while bin_iter.has_next():
n1 = bin_iter.get_next()
if area <= a0 * n1 * density:
bin_iter.save()
bin_iter.down()
else:
bin_iter.up()
return bin_iter.get_last_save()
def interval_to_track(self, layer_id: int,
intv: Tuple[int, int]) -> Tuple[HalfInt, int]:
"""Convert given coordinates to track number and width.
Parameters
----------
layer_id : int
the layer number.
intv : Tuple[int, int]
lower and upper coordinates perpendicular to the track direction.
Returns
-------
track : HalfInt
the track number
width : int
the track width, in number of tracks.
"""
start, stop = intv
htr = self.coord_to_htr(layer_id, (start + stop) // 2, RoundMode.NONE,
False)
width = stop - start
# binary search to take width override into account
bin_iter = BinaryIterator(1, None)
while bin_iter.has_next():
cur_ntr = bin_iter.get_next()
wire_width = self.get_wire_total_width(layer_id, cur_ntr)
if wire_width == width:
return HalfInt(htr), cur_ntr
elif wire_width > width:
bin_iter.down()
else:
bin_iter.up()
# never found solution; width is not quantized.
raise ValueError('Interval {} on layer {} width not quantized'.format(
intv, layer_id))
async def _get_stack(
self,
dut_params: Dict[str, Any],
mm_specs: Dict[str, Any],
r_targ: float,
stack_max: Optional[int] = None) -> Tuple[np.ndarray, np.ndarray]:
"""Binary searches the stack size to hit target r_targ output resistance.
If stack_max is None, we skip sizing. This is set when sizing the main driver.
NOTE: this function modifies dut_params and tbm_specs.
Parameters
----------
dut_params: Dict[str, Any]
Driver generator parameters
mm_specs: Dict[str, Any]
Specs for DriverPullUpDownMM
r_targ:
Target output resistance
stack_max:
Maximum allowed transistor stack size
Returns
-------
r_pu, r_pd: Tuple[np.ndarray, np.ndarray]
Measured pull-up / pull-down output resistance across given corners
"""
if not stack_max:
dut_params['stack'] = 1
sim_id = f'stack_1'
r_pu, r_pd = await self._get_resistance(sim_id, dut_params,
mm_specs)
return r_pu, r_pd
r_best = 0.0
bin_iter = BinaryIterator(1, None)
while bin_iter.has_next():
cur_stack = bin_iter.get_next()
while bin_iter.has_next() and cur_stack > stack_max:
bin_iter.down(float('inf'))
cur_stack = bin_iter.get_next()
if cur_stack > stack_max:
break
dut_params['stack'] = cur_stack
sim_id = f'stack_{cur_stack}'
r_pu, r_pd = await self._get_resistance(sim_id, dut_params,
mm_specs)
r_test = min(np.min(r_pu), np.min(r_pd))
r_best = max(r_test, r_best)
if r_targ > min(np.min(r_pu), np.min(r_pd)):
bin_iter.up(r_targ - min(np.min(r_pu), np.min(r_pd)))
else:
bin_iter.save_info((cur_stack, r_pu, r_pd))
bin_iter.down(r_targ - min(np.min(r_pu), np.min(r_pd)))
save_info = bin_iter.get_last_save_info()
if save_info is None:
self.error(f'Cannot meet spec with stack_max = {stack_max}, '
f'r_best = {r_best:.4g}')
stack, r_pu, r_pd = bin_iter.get_last_save_info()
dut_params['stack'] = stack
return r_pu, r_pd
async def _design_lvl_shift_inv_pdn(self, pseg: int, nseg: int,
out_inv_m: int, fanout: float,
pinfo: Any, tbm_specs: Dict[str, Any],
has_rst, dual_output, vin,
vout) -> int:
"""
This function figures out the NMOS nseg for the inverter given the target delay
TODO: Make this use digitaldB instead
"""
min_fanout: float = get_tech_global_info('bag3_digital')['min_fanout']
inv_beta: float = get_tech_global_info('bag3_digital')['inv_beta']
tb_params = self._get_full_tb_params()
# Use a binary iterator to find the NMOS size
max_nseg = int(np.round(nseg / min_fanout))
iterator = BinaryIterator(1, max_nseg)
load_seg = nseg + (pseg if has_rst else 0)
inv_pseg = int(
np.round(inv_beta * load_seg / ((1 + inv_beta) * fanout)))
inv_pseg = 1 if inv_pseg == 0 else inv_pseg
all_corners = get_tech_global_info(
'bag3_digital')['signoff_envs']['all_corners']
while iterator.has_next():
inv_nseg = iterator.get_next()
inv_in_nseg, inv_in_pseg = self._size_input_inv_for_fanout(
inv_pseg, inv_nseg, pseg, nseg, fanout, has_rst)
dut_params = self._get_lvl_shift_params_dict(
pinfo, pseg, nseg, inv_pseg, inv_nseg, inv_in_pseg,
inv_in_nseg, out_inv_m, has_rst, dual_output)
dut = await self.async_new_dut('lvshift', STDCellWrapper,
dut_params)
err_worst = -1 * float('Inf')
for env in all_corners['envs']:
tbm_specs['sim_envs'] = [env]
tbm_specs['sim_params']['vdd_in'] = all_corners[vin][env]
tbm_specs['sim_params']['vdd'] = all_corners[vout][env]
tbm = cast(CombLogicTimingTB,
self.make_tbm(CombLogicTimingTB, tbm_specs))
sim_results = await self.async_simulate_tbm_obj(
f'sim_inv_nseg_{inv_nseg}_{env}', dut, tbm, tb_params)
tdr_cur, tdf_cur = CombLogicTimingTB.get_output_delay(
sim_results.data,
tbm.specs,
'inb_buf',
'in_buf',
True,
in_pwr='vdd_in',
out_pwr='vdd_in')
target_cur, _ = CombLogicTimingTB.get_output_delay(
sim_results.data,
tbm.specs,
'inb_buf',
'midp',
True,
in_pwr='vdd_in',
out_pwr='vdd')
# Check for error conditions
if math.isinf(np.max(tdr_cur)) or math.isinf(
np.max(tdf_cur)) or math.isinf(np.max(target_cur)):
raise ValueError(
"Got infinite delay in level shifter design script (sizing inverter NMOS)."
)
if np.min(tdr_cur) < 0 or np.min(target_cur) < 0:
raise ValueError(
"Got negative delay in level shifter design script (sizing inverter NMOS). "
)
err_cur = tdr_cur[0] - target_cur[0]
if err_cur > err_worst:
err_worst = err_cur
worst_env = env
tdr = tdr_cur[0]
target = target_cur[0]
'''
print(f'iter: {inv_nseg}')
print(f'env: {worst_env}, tdr: {tdr}, target: {target}')
'''
if tdr < target:
iterator.down(target - tdr)
iterator.save_info(inv_nseg)
else:
iterator.up(target - tdr)
tmp_inv_nseg = iterator.get_last_save_info()
if tmp_inv_nseg is None:
tmp_inv_nseg = max_nseg
self.warn(
"Could not size pull down of inverter to meet required delay, picked the "
"max inv_nseg based on min_fanout.")
return tmp_inv_nseg
def design_amp(amp_specs, nch_db, pch_db):
sim_env = amp_specs['sim_env']
vdd = amp_specs['vdd']
vtail = amp_specs['vtail']
vgs_res = amp_specs['vgs_res']
gain_min = amp_specs['gain_min']
bw_min = amp_specs['bw_min']
cload = amp_specs['cload']
fun_ibiasn = nch_db.get_function('ibias', env=sim_env)
fun_gmn = nch_db.get_function('gm', env=sim_env)
fun_gdsn = nch_db.get_function('gds', env=sim_env)
fun_cdn = nch_db.get_function('cdb', env=sim_env) + nch_db.get_function(
'cds', env=sim_env)
fun_cgsn = nch_db.get_function('cgs', env=sim_env)
fun_ibiasp = pch_db.get_function('ibias', env=sim_env)
fun_gdsp = pch_db.get_function('gds', env=sim_env)
fun_cdp = pch_db.get_function('cdd', env=sim_env)
vgsn_idx = nch_db.get_fun_arg_index('vgs')
vgsn_min, vgsn_max = fun_ibiasn.get_input_range(vgsn_idx)
num_pts = int(math.ceil((vgsn_max - vgsn_min) / vgs_res))
vgs_list = np.linspace(vgsn_min, vgsn_max, num_pts + 1).tolist()
vgsp_idx = pch_db.get_fun_arg_index('vgs')
vgsp_min, vgsp_max = fun_ibiasp.get_input_range(vgsp_idx)
# sweep vgs, find best point
performance = None
for vgsn_cur in vgs_list:
vout = vgsn_cur + vtail
narg = nch_db.get_fun_arg(vgs=vgsn_cur, vds=vgsn_cur, vbs=vtail)
ibiasn_unit = fun_ibiasn(narg)
gmn_unit = fun_gmn(narg)
gdsn_unit = fun_gdsn(narg)
cdn_unit = fun_cdn(narg)
cgsn_unit = fun_cgsn(narg)
# find max gain
def gain_fun1(vgsp_test):
parg_test = pch_db.get_fun_arg(vgs=vgsp_test,
vds=vout - vdd,
vbs=0)
ibiasp_unit_test = fun_ibiasp(parg_test)
gdsp_unit_test = fun_gdsp(parg_test)
return gmn_unit / ibiasn_unit / (gdsn_unit / ibiasn_unit +
gdsp_unit_test / ibiasp_unit_test)
result = minimize_cost_golden_float(gain_fun1,
gain_min,
vgsp_min,
vgsp_max,
tol=vgs_res / 10)
opt_vgsp = result.x
if opt_vgsp is None:
print('vgsn = %.4g, max gain: %.4g' % (vgsn_cur, result.vmax))
break
# get number of input fingers needed to achieve gain_max with minimum number of load fingers
seg_in_init = fun_ibiasp(
pch_db.get_fun_arg(vgs=opt_vgsp, vds=vout - vdd,
vbs=0)) * 2 / ibiasn_unit
seg_in_init = int(round(seg_in_init / 2)) * 2
# sweep gm size
seg_in_iter = BinaryIterator(2, None, step=2)
seg_in_iter.set_current(seg_in_init)
while seg_in_iter.has_next():
seg_in = seg_in_iter.get_next()
ibiasn = seg_in * ibiasn_unit
gmn = seg_in * gmn_unit
gdsn = seg_in * gdsn_unit
# sweep load size
seg_load_iter = BinaryIterator(2, None, step=2)
while seg_load_iter.has_next():
seg_load = seg_load_iter.get_next()
vbp, sgn = find_load_bias(pch_db, vdd, vout, vgsp_min,
vgsp_max, ibiasn, seg_load,
fun_ibiasp)
if vbp is None:
if sgn > 0:
seg_load_iter.up()
else:
seg_load_iter.down()
else:
parg = pch_db.get_fun_arg(vgs=vbp - vdd,
vds=vout - vdd,
vbs=0)
gdsp = seg_load * fun_gdsp(parg)
if gmn / (gdsp + gdsn) >= gain_min:
seg_load_iter.save_info((vbp, parg))
seg_load_iter.down()
else:
seg_load_iter.up()
seg_load = seg_load_iter.get_last_save()
if seg_load is None:
# no load solution -> cannot meet gain spec.
break
vbp, parg = seg_load_iter.get_last_save_info()
gdsp = seg_load * fun_gdsp(parg)
cdp = seg_load * fun_cdp(parg)
cdn = seg_in * cdn_unit
cgsn = seg_in * cgsn_unit
ro_cur = 1 / (gdsp + gdsn)
gain_cur = gmn * ro_cur
cpar_cur = cdn + cdp + (1 + 1 / gain_cur) * cgsn
# check intrinsic bandwidth good
if 1 / (ro_cur * cpar_cur * 2 * np.pi) < bw_min:
break
cload_cur = cload + cpar_cur
bw_cur = 1 / (ro_cur * cload_cur * 2 * np.pi)
if bw_cur < bw_min:
seg_in_iter.up()
else:
seg_in_iter.save_info(
(seg_load, vbp, ibiasn, gain_cur, bw_cur))
seg_in_iter.down()
if seg_in_iter.get_last_save() is None:
continue
seg_in = seg_in_iter.get_last_save()
seg_load, vbp, ibiasn, gain_cur, bw_cur = seg_in_iter.get_last_save_info(
)
if performance is None or performance[0] > ibiasn:
performance = (ibiasn, gain_cur, bw_cur, seg_in, seg_load,
vgsn_cur, vbp)
if performance is None:
return None
ibias_opt, gain_opt, bw_opt, seg_in, seg_load, vgs_in, vload = performance
vio = vtail + vgs_in
seg_tail, vbias = find_tail_bias(fun_ibiasn, nch_db, vtail, vgsn_min,
vgsn_max, seg_in, ibias_opt)
return dict(
ibias=2 * ibias_opt,
gain=gain_opt,
bw=bw_opt,
seg_in=seg_in,
seg_load=seg_load,
seg_tail=seg_tail,
vtail=vbias,
vindc=vio,
voutdc=vio,
vload=vload,
vgs_in=vgs_in,
)
def draw_layout(self):
# type: () -> None
lch = self.params['lch']
ptap_w = self.params['ptap_w']
ntap_w = self.params['ntap_w']
wp = self.params['wp']
wn = self.params['wn']
thp = self.params['thp']
thn = self.params['thn']
nx = self.params['nx']
ny = self.params['ny']
fill_config = self.params['fill_config']
top_layer = self.params['top_layer']
sup_width = self.params['sup_width']
options = self.params['options']
show_pins = self.params['show_pins']
if options is None:
options = {}
# get power fill size
w_tot, h_tot = self.grid.get_fill_size(top_layer, fill_config, unit_mode=True)
w_tot *= nx
h_tot *= ny
# get number of fingers
info = AnalogBaseInfo(self.grid, lch, 0, top_layer=top_layer)
bin_iter = BinaryIterator(2, None)
while bin_iter.has_next():
fg_cur = bin_iter.get_next()
w_cur = info.get_placement_info(fg_cur).tot_width
if w_cur < w_tot:
bin_iter.save()
bin_iter.up()
elif w_cur > w_tot:
bin_iter.down()
else:
bin_iter.save()
break
fg_tot = bin_iter.get_last_save()
if fg_tot is None:
raise ValueError('Decaep cell width exceed fill width.')
self.draw_base(lch, fg_tot, ptap_w, ntap_w, [wn], [thn], [wp], [thp],
ng_tracks=[1], pg_tracks=[1], n_orientations=['MX'],
p_orientations=['R0'], top_layer=top_layer, min_height=h_tot,
**options)
if self.bound_box.height_unit > h_tot:
raise ValueError('Decap cell height exceed fill height.')
nmos = self.draw_mos_conn('nch', 0, 0, fg_tot, 0, 0)
pmos = self.draw_mos_conn('pch', 0, 0, fg_tot, 2, 2, gate_pref_loc='s')
vss_tid = self.make_track_id('pch', 0, 'g', 0)
vdd_tid = self.make_track_id('nch', 0, 'g', 0)
self.connect_to_substrate('ptap', nmos['d'])
self.connect_to_substrate('ntap', pmos['s'])
vss_g = self.connect_to_tracks([nmos['s'], pmos['g']], vss_tid)
vdd_g = self.connect_to_tracks([pmos['d'], nmos['g']], vdd_tid)
vss, vdd = self.fill_dummy(vdd_width=sup_width, vss_width=sup_width)
vss.append(vss_g)
vdd.append(vdd_g)
self.add_pin('VSS', vss, label='VSS:', show=show_pins)
self.add_pin('VDD', vdd, label='VDD:', show=show_pins)
def draw_layout(self):
# type: () -> None
top_layer = self.params['top_layer']
lch = self.params['lch']
w = self.params['w']
sub_type = self.params['sub_type']
threshold = self.params['threshold']
port_width = self.params['port_width']
well_width = self.params['well_width']
end_mode = self.params['end_mode']
is_passive = self.params['is_passive']
max_nxblk = self.params['max_nxblk']
port_tid = self.params['port_tid']
show_pins = self.params['show_pins']
half_blk_y = self.params['half_blk_y']
half_blk_x = self.params['half_blk_x']
res = self.grid.resolution
well_width = int(round(well_width / res))
right_end = (end_mode & 8) != 0
left_end = (end_mode & 4) != 0
top_end = (end_mode & 2) != 0
bot_end = (end_mode & 1) != 0
# get layout info, also set RoutingGrid to substrate grid.
layout_info = AnalogBaseInfo(self.grid,
lch,
0,
top_layer=top_layer,
end_mode=end_mode,
half_blk_y=half_blk_y,
half_blk_x=half_blk_x)
# compute template width in number of sd pitches
# find maximum number of fingers we can draw
bin_iter = BinaryIterator(1, None)
while bin_iter.has_next():
cur_fg = bin_iter.get_next()
cur_pinfo = layout_info.get_placement_info(cur_fg)
cur_core_width = cur_pinfo.core_width
if cur_core_width == well_width:
bin_iter.save_info(cur_pinfo)
break
elif cur_core_width < well_width:
bin_iter.save_info(cur_pinfo)
bin_iter.up()
else:
bin_iter.down()
sub_fg_tot = bin_iter.get_last_save()
if sub_fg_tot is None:
raise ValueError('Cannot draw substrate that fit in width: %d' %
well_width)
# check width parity requirement
if max_nxblk > 0:
blkw = self.grid.get_block_size(top_layer, unit_mode=True)[0]
place_info = bin_iter.get_last_save_info()
cur_nxblk = place_info.tot_width // blkw
while sub_fg_tot > 0 and (cur_nxblk > max_nxblk or
(max_nxblk - cur_nxblk) % 2 != 0):
sub_fg_tot -= 1
place_info = layout_info.get_placement_info(sub_fg_tot)
cur_nxblk = place_info.tot_width // blkw
if sub_fg_tot <= 0:
raise ValueError('Cannot draw substrate with width = %d, '
'max_nxblk = %d' % (well_width, max_nxblk))
layout_info.set_fg_tot(sub_fg_tot)
self.grid = layout_info.grid
place_info = layout_info.get_placement_info(sub_fg_tot)
edgel_x0 = place_info.edge_margins[0]
tot_width = place_info.tot_width
# create masters
master_list = [
self.new_template(params=dict(
lch=lch,
fg=sub_fg_tot,
sub_type=sub_type,
threshold=threshold,
is_end=bot_end,
top_layer=top_layer,
),
temp_cls=AnalogEndRow),
self.new_template(params=dict(
lch=lch,
w=w,
sub_type=sub_type,
threshold=threshold,
fg=sub_fg_tot,
top_layer=top_layer,
options=dict(is_passive=is_passive),
),
temp_cls=AnalogSubstrate),
self.new_template(params=dict(
lch=lch,
fg=sub_fg_tot,
sub_type=sub_type,
threshold=threshold,
is_end=top_end,
top_layer=top_layer,
),
temp_cls=AnalogEndRow),
]
ycur = 0
array_box = BBox.get_invalid_bbox()
sub_conn, inst = None, None
for master, orient in zip(master_list, ['R0', 'R0', 'MX']):
if orient == 'MX':
ycur += master.array_box.top_unit
name_id = master.get_layout_basename()
edge_layout_info = master.get_edge_layout_info()
xcur = edgel_x0
if left_end:
edge_info = master.get_left_edge_info()
edge_params = dict(
is_end=True,
guard_ring_nf=0,
name_id=name_id,
layout_info=edge_layout_info,
adj_blk_info=edge_info,
)
edge_master = self.new_template(params=edge_params,
temp_cls=AnalogEdge)
if not edge_master.is_empty:
edge_inst = self.add_instance(edge_master,
loc=(edgel_x0, ycur),
orient=orient,
unit_mode=True)
array_box = array_box.merge(edge_inst.array_box)
xcur = edge_inst.array_box.right_unit
inst = self.add_instance(master,
loc=(xcur, ycur),
orient=orient,
unit_mode=True)
array_box = array_box.merge(inst.array_box)
if isinstance(master, AnalogSubstrate):
conn_params = dict(
layout_info=edge_layout_info,
layout_name=name_id + '_subconn',
is_laygo=False,
)
conn_master = self.new_template(params=conn_params,
temp_cls=AnalogSubstrateConn)
sub_conn = self.add_instance(conn_master,
loc=(xcur, ycur),
orient=orient,
unit_mode=True)
xcur = inst.array_box.right_unit
if right_end:
edge_info = master.get_right_edge_info()
edge_params = dict(
is_end=True,
guard_ring_nf=0,
name_id=name_id,
layout_info=edge_layout_info,
adj_blk_info=edge_info,
)
edge_master = self.new_template(params=edge_params,
temp_cls=AnalogEdge)
if not edge_master.is_empty:
xcur += edge_master.array_box.right_unit
eor = 'MY' if orient == 'R0' else 'R180'
edge_inst = self.add_instance(edge_master,
loc=(xcur, ycur),
orient=eor,
unit_mode=True)
array_box = array_box.merge(edge_inst.array_box)
if orient == 'R0':
ycur += master.array_box.top_unit
# calculate substrate Y coordinates
imp_yb, thres_yb = master_list[0].sub_ysep
imp_yt, thres_yt = master_list[2].sub_ysep
self._sub_bndy = (imp_yb, ycur - imp_yt), (thres_yb, ycur - thres_yt)
# get left/right substrate coordinates
tot_imp_box = BBox.get_invalid_bbox()
for lay in self.grid.tech_info.get_implant_layers('ptap'):
tot_imp_box = tot_imp_box.merge(self.get_rect_bbox(lay))
for lay in self.grid.tech_info.get_implant_layers('ntap'):
tot_imp_box = tot_imp_box.merge(self.get_rect_bbox(lay))
if not tot_imp_box.is_physical():
self._sub_bndx = None, None
else:
self._sub_bndx = tot_imp_box.left_unit, tot_imp_box.right_unit
# set array box and size
self.array_box = array_box
bound_box = BBox(0,
0,
tot_width,
inst.bound_box.top_unit,
res,
unit_mode=True)
if self.grid.size_defined(top_layer):
self.set_size_from_bound_box(top_layer, bound_box)
else:
self.prim_bound_box = bound_box
self.prim_top_layer = top_layer
hm_layer = layout_info.mconn_port_layer + 1
if port_tid is None:
# find center track index
hm_mid = self.grid.coord_to_nearest_track(hm_layer,
self.array_box.yc_unit,
mode=0,
half_track=True,
unit_mode=True)
# connect to horizontal metal layer.
hm_pitch = self.grid.get_track_pitch(hm_layer, unit_mode=True)
ntr = self.array_box.height_unit // hm_pitch # type: int
if port_width is None:
port_width = self.grid.get_max_track_width(
hm_layer, 1, ntr, half_end_space=False)
port_tid = TrackID(hm_layer, hm_mid, width=port_width)
else:
port_tid = TrackID(hm_layer, port_tid[0], width=port_tid[1])
port_name = 'VDD' if sub_type == 'ntap' else 'VSS'
sub_wires = self.connect_to_tracks(
sub_conn.get_port(port_name).get_pins(hm_layer - 1), port_tid)
self.add_pin(port_name, sub_wires, show=show_pins)
self._fg_tot = sub_fg_tot
def draw_layout(self):
lch = self.params['lch']
ntap_w = self.params['ntap_w']
w = self.params['w']
fg_ref = self.params['fg_ref']
threshold = self.params['threshold']
out_xc_list = self.params['out_xc_list']
supply_tracks = self.params['supply_tracks']
em_specs = self.params['em_specs']
tr_widths = self.params['tr_widths']
tr_spaces = self.params['tr_spaces']
tot_width = self.params['tot_width']
guard_ring_nf = self.params['guard_ring_nf']
show_pins = self.params['show_pins']
# get AnalogBaseInfo
hm_layer = self.mos_conn_layer + 1
ym_layer = hm_layer + 1
layout_info = AnalogBaseInfo(self.grid,
lch,
guard_ring_nf,
top_layer=ym_layer,
half_blk_y=False)
# compute total number of fingers to achieve target width.
bin_iter = BinaryIterator(2, None, step=2)
while bin_iter.has_next():
fg_cur = bin_iter.get_next()
w_cur = layout_info.get_placement_info(fg_cur).tot_width
if w_cur < tot_width:
bin_iter.save()
bin_iter.up()
elif w_cur > tot_width:
bin_iter.down()
else:
bin_iter.save()
break
fg_tot = bin_iter.get_last_save()
# find number of tracks needed for output tracks from EM specs
hm_tr_w_out = self.grid.get_min_track_width(hm_layer, **em_specs)
hm_tr_sp_out = self.grid.get_num_space_tracks(hm_layer,
hm_tr_w_out,
half_space=True)
hm_w = self.grid.get_track_width(hm_layer, hm_tr_w_out, unit_mode=True)
ym_tr_w = self.grid.get_min_track_width(ym_layer,
bot_w=hm_w,
**em_specs,
unit_mode=True)
# construct track width/space dictionary from EM specs
tr_manager = TrackManager(self.grid,
tr_widths,
tr_spaces,
half_space=True)
tr_w_dict = {
'in': {
hm_layer: tr_manager.get_width(hm_layer, 'in')
},
'out': {
hm_layer: hm_tr_w_out,
ym_tr_w: ym_tr_w
},
}
tr_sp_dict = {
('in', 'out'): {
hm_layer:
max(hm_tr_sp_out, tr_manager.get_space(hm_layer,
('in', 'out')))
},
}
tr_manager = TrackManager(self.grid,
tr_w_dict,
tr_sp_dict,
half_space=True)
pw_list = [w, w, w]
pth_list = [threshold, threshold, threshold]
wire_names = dict(
nch=[],
pch=[
dict(
ds=['out'],
g=['in'],
),
dict(
g=['out'],
ds=['out'],
ds2=['out'],
),
dict(g=['in'], ds=['out']),
],
)
# draw transistor rows
self.draw_base(lch,
fg_tot,
ntap_w,
ntap_w, [], [],
pw_list,
pth_list,
tr_manager=tr_manager,
wire_names=wire_names,
p_orientations=['MX', 'R0', 'R0'],
guard_ring_nf=guard_ring_nf,
pgr_w=ntap_w,
ngr_w=ntap_w,
top_layer=ym_layer,
half_blk_y=False)
outn_tid = self.get_wire_id('pch', 0, 'ds', wire_name='out')
inp_tid = self.get_wire_id('pch', 0, 'g', wire_name='in')
bias_tid = self.get_wire_id('pch', 1, 'g', wire_name='out')
vdd_tid = self.get_wire_id('pch', 1, 'ds', wire_name='out')
tail_tid = self.get_wire_id('pch', 1, 'ds2', wire_name='out')
inn_tid = self.get_wire_id('pch', 2, 'g', wire_name='in')
outp_tid = self.get_wire_id('pch', 2, 'ds', wire_name='out')
out_pitch = out_xc_list[1] - out_xc_list[0]
sd_pitch = layout_info.sd_pitch_unit
if out_pitch % sd_pitch != 0:
raise ValueError('Oops')
fg = out_pitch // sd_pitch - fg_ref
# draw transistors and connect
inp_list = []
inn_list = []
tail_list = []
bias_list = []
vdd_m_list = []
outp_list = []
outn_list = []
layout_info = self.layout_info
num_out = len(out_xc_list)
for idx, xc in enumerate(out_xc_list):
ym_idx = self.grid.coord_to_track(ym_layer, xc, unit_mode=True)
vtid = TrackID(ym_layer, ym_idx, width=ym_tr_w)
# find column index that centers on given track index
x_coord = self.grid.track_to_coord(ym_layer,
ym_idx,
unit_mode=True)
col_center = layout_info.coord_to_col(x_coord, unit_mode=True)
col_idx = col_center - (fg // 2)
# draw transistors
if idx == 0:
mref = self.draw_mos_conn('pch',
1,
col_idx - fg_ref,
fg_ref,
2,
0,
d_net='ibias',
diode_conn=True,
gate_pref_loc='d')
bias_list.append(mref['g'])
bias_list.append(mref['d'])
vdd_m_list.append(mref['s'])
mtop = self.draw_mos_conn('pch',
2,
col_idx,
fg,
2,
0,
s_net='ioutp',
d_net='tail')
mbot = self.draw_mos_conn('pch',
0,
col_idx,
fg,
0,
2,
s_net='ioutn',
d_net='tail')
mtail = self.draw_mos_conn('pch',
1,
col_idx,
fg,
2,
0,
gate_pref_loc='s',
s_net='',
d_net='tail')
mref = self.draw_mos_conn('pch',
1,
col_idx + fg,
fg_ref,
2,
0,
gate_pref_loc='d',
diode_conn=True,
d_net='ibias')
# connect
inp_list.append(mbot['g'])
inn_list.append(mtop['g'])
bias_list.append(mref['g'])
bias_list.append(mref['d'])
bias_list.append(mtail['g'])
tail_list.append(mtop['d'])
tail_list.append(mbot['d'])
tail_list.append(mtail['d'])
vdd_m_list.append(mtail['s'])
vdd_m_list.append(mref['s'])
outp_h = self.connect_to_tracks(mtop['s'], outp_tid)
outp_list.append(outp_h)
self.add_pin('ioutp',
self.connect_to_tracks(outp_h, vtid),
show=show_pins)
outn_h = self.connect_to_tracks(mbot['s'], outn_tid)
outn_list.append(outn_h)
self.add_pin('ioutn',
self.connect_to_tracks(outn_h, vtid),
show=show_pins)
self.connect_wires(outp_list)
self.connect_wires(outn_list)
self.add_pin('inp',
self.connect_to_tracks(inp_list,
inp_tid,
track_lower=0,
unit_mode=True),
show=show_pins)
self.add_pin('inn',
self.connect_to_tracks(inn_list,
inn_tid,
track_lower=0,
unit_mode=True),
show=show_pins)
ibias = self.connect_to_tracks(bias_list,
bias_tid,
track_lower=0,
unit_mode=True)
self.add_pin('ibias', ibias, show=show_pins)
self.connect_to_tracks(tail_list,
tail_tid,
track_lower=ibias.lower_unit,
track_upper=ibias.upper_unit,
unit_mode=True)
vdd_m = self.connect_to_tracks(vdd_m_list, vdd_tid)
_, vdd_warrs = self.fill_dummy()
vdd_warrs.append(vdd_m)
right_tidx = 0
for tidx in supply_tracks:
vtid = TrackID(ym_layer, tidx, width=ym_tr_w)
right_tidx = max(right_tidx, tidx)
self.add_pin('VDD',
self.connect_to_tracks(vdd_warrs, vtid),
show=show_pins)
for xc in out_xc_list:
tidx = self.grid.coord_to_track(ym_layer, xc, unit_mode=True)
vtid = TrackID(ym_layer, tidx, width=ym_tr_w)
self.add_pin('VDD',
self.connect_to_tracks(vdd_m, vtid),
show=show_pins)
self.fill_box = bnd_box = self.bound_box
for lay in range(1, self.top_layer):
self.do_max_space_fill(lay, bnd_box, fill_pitch=3)
self._sch_params = dict(
lch=lch,
w_dict={
'in': w,
'tail': w
},
th_dict={
'in': threshold,
'tail': threshold
},
seg_dict={
'in': fg * num_out,
'tail': fg * num_out,
'ref': fg_ref * (num_out + 1)
},
dum_info=self.get_sch_dummy_info(),
)
ratio = fg * num_out / (fg_ref * (num_out + 1))
scale = num_out / ratio
self._ibias_em_specs = em_specs.copy()
for key in ['idc', 'iac_rms', 'iac_peak']:
if key in em_specs:
self._ibias_em_specs[key] *= scale
async def _design_lvl_shift_inv_pun(self, pseg: int, nseg: int,
inv_nseg: int, out_inv_m: int,
fanout: float, pinfo: Any,
tbm_specs: Dict[str, Any], has_rst,
dual_output, vin,
vout) -> Tuple[int, int]:
"""
Given the NMOS pull down size, this function will design the PMOS pull up so that the delay
mismatch is minimized.
# TODO: Need to double check on how this handles corners
"""
inv_beta = get_tech_global_info('bag3_digital')['inv_beta']
tb_params = self._get_full_tb_params()
# Use a binary iterator to find the PMOS size
load_seg = nseg + (pseg if has_rst else 0)
inv_pseg_nom = int(
np.round(inv_beta * load_seg / ((1 + inv_beta) * fanout)))
inv_pseg_nom = 1 if inv_pseg_nom == 0 else inv_pseg_nom
iterator = BinaryIterator(-inv_pseg_nom + 1, 0)
err_best = float('inf')
inv_in_nseg, inv_in_pseg = self._size_input_inv_for_fanout(
inv_pseg_nom, inv_nseg, pseg, nseg, fanout, has_rst)
all_corners = get_tech_global_info(
'bag3_digital')['signoff_envs']['all_corners']
while iterator.has_next():
pseg_off = iterator.get_next()
inv_pseg = inv_pseg_nom + pseg_off
dut_params = self._get_lvl_shift_params_dict(
pinfo, pseg, nseg, inv_pseg, inv_nseg, inv_in_nseg,
inv_in_pseg, out_inv_m, has_rst, dual_output)
dut = await self.async_new_dut('lvshift', STDCellWrapper,
dut_params)
err_worst = -1 * float('Inf')
for env in all_corners['envs']:
tbm_specs['sim_envs'] = [env]
tbm_specs['sim_params']['vdd_in'] = all_corners[vin][env]
tbm_specs['sim_params']['vdd'] = all_corners[vout][env]
tbm = cast(CombLogicTimingTB,
self.make_tbm(CombLogicTimingTB, tbm_specs))
sim_results = await self.async_simulate_tbm_obj(
f'sim_inv_pseg_{inv_pseg}_{env}', dut, tbm, tb_params)
tdr_cur, tdf_cur = CombLogicTimingTB.get_output_delay(
sim_results.data,
tbm.specs,
'in',
'out',
False,
in_pwr='vdd_in',
out_pwr='vdd')
'''
plt.figure()
plt.plot(sim_results.data['time'].flatten(), sim_results.data['in'].flatten(), 'b')
plt.plot(sim_results.data['time'].flatten(), sim_results.data['inb_buf'].flatten(), 'g')
plt.plot(sim_results.data['time'].flatten(), sim_results.data['in_buf'].flatten(), 'r')
plt.plot(sim_results.data['time'].flatten(), sim_results.data['midn'].flatten(), 'k')
plt.plot(sim_results.data['time'].flatten(), sim_results.data['midp'].flatten(), 'c')
plt.plot(sim_results.data['time'].flatten(), sim_results.data['out'].flatten(), 'm')
plt.legend(['in', 'inb_buf', 'in_buf', 'midn', 'midp', 'out'])
plt.title(f'pseg_off: {pseg_off}, pseg: {inv_pseg}, nseg: {inv_nseg-pseg_off}, fanout: {fanout}')
plt.show(block=False)
'''
# Error checking
if math.isinf(np.max(tdr_cur)) or math.isinf(np.max(tdf_cur)):
raise ValueError("Got infinite delay!")
if np.min(tdr_cur) < 0 or np.min(tdf_cur) < 0:
raise ValueError("Got negative delay.")
err_cur = np.abs(tdr_cur[0] - tdf_cur[0])
if err_cur > err_worst:
err_worst = err_cur
worst_env = env
tdr = tdr_cur[0]
tdf = tdf_cur[0]
'''
print(f'iter: {inv_pseg}')
print(f'env: {worst_env}, tdr: {tdr}, tdf: {tdf}')
breakpoint()
'''
if tdr < tdf:
iterator.down(tdr - tdf)
else:
iterator.up(tdr - tdf)
err_abs = np.abs(tdr - tdf)
if err_abs < err_best:
err_best = err_abs
iterator.save_info(pseg_off)
pseg_off = iterator.get_last_save_info()
pseg_off = 0 if pseg_off is None else pseg_off # Should only hit this case if inv_pseg_nom = 1
inv_pseg = inv_pseg_nom + pseg_off
return inv_pseg, inv_nseg - 0 * pseg_off
async def async_design(self, pinfo: Mapping[str, Any], nbits: int,
rtol: float, atol: float, tbit: float, trf: float,
cload: float, mc_params: Param, num_cores: int,
target: Mapping[str, Any],
delay_cell_params: Mapping[str, Any],
**kwargs: Mapping[str, Any]) -> Mapping[str, Any]:
td_min = target['td_min']
td_max = target['td_max']
t_max = target['t_max']
td_sigma = target['td_sigma']
tristate_seg = kwargs.get('tristate_seg', self.global_info['seg_min'])
tristate_stack = kwargs.get('tristate_stack', 1)
seg_buf_abs_max = kwargs.get('seg_buf_abs_max', 50)
seg_buf_max_override = kwargs.get('seg_buf_max_override', None)
seg_buf_min_override = kwargs.get('seg_buf_min_override', None)
design_using_signoff = kwargs.get('design_using_signoff', False)
mc_corner = kwargs.get('mc_corner', 'tt_25')
mc_env_override = kwargs.get("mc_env_override", None)
mc_worst_corner = kwargs.get("mc_worst_corner", True)
plot_result: bool = kwargs.get('plot_result', False)
dsn_monte_carlo: bool = kwargs.get('dsn_monte_carlo', True)
gen_specs: Optional[Mapping[str,
Any]] = kwargs.get('gen_cell_specs', None)
gen_cell_args: Optional[Mapping[str, Any]] = kwargs.get(
'gen_cell_args', None)
# 0. Setup design environments and the testbench manager
if design_using_signoff:
dsn_envs = self.global_info['signoff_envs']
dsn_env_names = dsn_envs['all_corners']['envs']
dsn_env_vdds = dsn_envs['all_corners']['vdd']
else:
dsn_envs = self.global_info['dsn_envs']
dsn_env_names = [
env for dct in dsn_envs.values() for env in dct['env']
]
dsn_env_vdds = {
e: dsn_envs[c]['vdd']
for c in dsn_envs.keys() for e in dsn_envs[c]['env']
}
if not mc_worst_corner and not mc_env_override:
raise ValueError(
"If not performing mc on the worst corner, specify mc_env_override!"
)
dut_pins = [
'a_in', 'b_in', 'intout', 'VDD', 'VSS', f'sp<{nbits - 1}:0>',
f'sn<{nbits - 1}:0>', 'a_in_buf'
]
tbm_dict = {}
for dsn_env in dsn_env_names:
tbm_specs = self._get_tbm_specs(
[dsn_env], dict(vdd={dsn_env: dsn_env_vdds[dsn_env]}),
dut_pins, tbit, trf, cload, nbits, rtol, atol)
tbm = cast(DigitalTranTB, self.make_tbm(DigitalTranTB, tbm_specs))
tbm_dict[dsn_env] = tbm
tbm_params = dict()
# 1. Setup the base phase interpolator and extract the input cap
pwr_domains = dict(b_in=('VSS', 'VDD'),
a_in=('VSS', 'VDD'),
out=('VSS', 'VDD'))
cin_dut_conns = dict(a_in=1)
for i in range(nbits):
for name, value in zip(['a_en', 'b_en', 'a_enb', 'b_enb'],
[1, 0, 0, 1]):
cin_dut_conns[f'{name}<{i}>'] = value
pwr_domains[f'{name}<{i}>'] = ('VSS', 'VDD')
gen_params = dict(cls_name=PhaseInterpolator.get_qualified_name(),
params=dict(
pinfo=pinfo,
unit_params={
'seg': tristate_seg,
'stack_p': tristate_stack,
'stack_n': tristate_stack
},
inv_params={
'seg': 2,
'stack_p': 1,
'stack_n': 1
},
nbits=nbits,
draw_sub=True,
export_outb=True,
abut_tristates=True,
))
pi_in_cap = await self._get_input_cap(
gen_params,
'b_in',
cload,
cin_dut_conns,
pwr_domains, [dict(pin='out', type='cap', value='c_out')],
vdd=dsn_env_vdds['tt_25'],
sim_envs=['tt_25'])
# 2. Setup the base delay cell and extract it's input cap
pin_names = ['bk1', 'ci_p', 'co_p', 'in_p', 'out_p']
pwr_domains = {pin_name: ('VSS', 'VDD') for pin_name in pin_names}
cin_dut_conns = dict(bk1=1, ci_p=0)
load_list = [
dict(pin='out_p', type='cap', value='c_out'),
dict(pin='co_p', type='cap', value='c_out')
]
gen_params = dict(cls_name=DelayCellCore.get_qualified_name(),
params=dict(pinfo=pinfo,
stand_alone=True,
**delay_cell_params))
dc_in_cap = await self._get_input_cap(gen_params,
'ci_p',
cload,
cin_dut_conns,
pwr_domains,
load_list,
vdd=dsn_env_vdds['tt_25'],
sim_envs=['tt_25'])
# 3. Size the delay cell to be able to drive the phase interpolator
dc_up_scale_factor = int(round(pi_in_cap / dc_in_cap))
delay_cell_params['seg_dict']['in'] *= dc_up_scale_factor
delay_cell_params['seg_dict']['out'] *= dc_up_scale_factor
delay_cell_params['seg_dict']['sr'] *= dc_up_scale_factor
nand_seg = delay_cell_params['seg_dict']['out'] * 2
inv_in_cap = self.global_info['cin_inv']['cin_per_seg']
inv_seg = int(round(np.sqrt(dc_in_cap * pi_in_cap) / inv_in_cap))
# 4. Upsize the buffer inverter on the output
self.log('-' * 80)
if seg_buf_min_override:
self.log(f"Minimum Segments Overridden to {seg_buf_min_override}")
min_seg_buf = seg_buf_min_override
else:
self.log('Find the min size for all the codes to be positive')
seg_buf_min_iter = BinaryIterator(2, None, 2)
while seg_buf_min_iter.has_next():
_seg_buf = seg_buf_min_iter.get_next()
dut_params = self._update_dut_params(
pinfo,
nbits,
tristate_seg,
seg_buf=_seg_buf,
seg_inv=inv_seg,
seg_nand=nand_seg,
num_cores=num_cores,
dc_params=delay_cell_params)
results = await self._measure_times(dsn_env_names,
tbm_dict,
dut_params,
tbm_params,
tbit,
nbits,
name=f'sim_min_{_seg_buf}')
# find min and max delay step
tstep_min = results['min_step']
tstep_max = results['max_step']
self.log(
f"Got min delay {tstep_min}, max delay {tstep_max}, with "
f"{_seg_buf} segments")
if tstep_min < 0:
seg_buf_min_iter.up()
else:
seg_buf_min_iter.save()
seg_buf_min_iter.down()
min_seg_buf = seg_buf_min_iter.get_last_save()
self.log('-' * 80)
if seg_buf_max_override:
self.log(f'Maximum Segments Overridden to {seg_buf_max_override}')
max_seg_buf = seg_buf_max_override
else:
self.log(
'Now find the maximum size for all the codes to be positive')
seg_buf_max_iter = BinaryIterator(10, None, 2)
max_reached = False
while seg_buf_max_iter.has_next():
_seg_buf = seg_buf_max_iter.get_next()
dut_params = self._update_dut_params(
pinfo,
nbits,
tristate_seg,
seg_buf=_seg_buf,
seg_inv=inv_seg,
seg_nand=nand_seg,
num_cores=num_cores,
dc_params=delay_cell_params)
results = await self._measure_times(dsn_env_names,
tbm_dict,
dut_params,
tbm_params,
tbit,
nbits,
name=f'sim_max_{_seg_buf}')
# find min and max delay step
tstep_min = results['min_step']
tstep_max = results['max_step']
self.log(
f"Got min delay {tstep_min}, max delay {tstep_max}, with "
f"{_seg_buf} segments")
if tstep_min < 0:
seg_buf_max_iter.down()
elif _seg_buf > seg_buf_abs_max:
max_reached = True
break
else:
seg_buf_max_iter.save()
seg_buf_max_iter.up()
max_seg_buf = seg_buf_max_iter.get_last_save(
) if not max_reached else seg_buf_abs_max
self.log('-' * 80)
self.log(
f'Minimum Buffer segments to keep positive delays: {min_seg_buf}')
self.log(
f'Maximum Buffer segments to keep positive delays: {max_seg_buf}')
seg_buf_bin_iter = BinaryIterator(min_seg_buf, max_seg_buf, 2)
while seg_buf_bin_iter.has_next():
_seg_buf = seg_buf_bin_iter.get_next()
dut_params = self._update_dut_params(pinfo,
nbits,
tristate_seg,
seg_buf=_seg_buf,
seg_inv=inv_seg,
seg_nand=nand_seg,
num_cores=num_cores,
dc_params=delay_cell_params)
results = await self._measure_times(dsn_env_names, tbm_dict,
dut_params, tbm_params, tbit,
nbits, 'sim_size')
tdelay_max = results['max_dly']
tstep_min = results['min_step']
tstep_max = results['max_step']
if tdelay_max > t_max and tstep_min > td_min and tstep_max < td_max:
# delay constraint violated, linearity constraint met
seg_buf_bin_iter.down()
elif tdelay_max < t_max and (tstep_min < td_min
or tstep_max > td_max):
# delay constraint met, linearity constraint violated
seg_buf_bin_iter.up()
elif tdelay_max < t_max and tstep_min > td_min and tstep_max < td_max:
# both constraints met
seg_buf_bin_iter.save_info((dut_params, results))
seg_buf_bin_iter.down()
else:
self.error(
'Both delay and linearity constraints violated, please relax specs.'
)
seg_buf_final = seg_buf_bin_iter.get_last_save()
if not seg_buf_final:
self.error(
"Design failed!, unable to meet linearity specs within range of inv sizes"
)
self.log(
f'Final output buffer size is {seg_buf_final}, before Monte Carlo sim.'
)
dut_params, results = seg_buf_bin_iter.get_last_save_info()
if dsn_monte_carlo:
# 5. Monte Carlo simulations
mc_tbm_dict = {}
if mc_worst_corner:
mc_envs = [mc_corner]
mc_vdd = dict(vdd={mc_corner: dsn_env_vdds[mc_corner]})
mc_tbm_specs = self._get_tbm_specs([mc_corner], mc_vdd,
dut_pins, tbit, trf, cload,
nbits, rtol, atol)
mc_tbm_specs['monte_carlo_params'] = mc_params
mc_tbm = cast(DigitalTranTB,
self.make_tbm(DigitalTranTB, mc_tbm_specs))
mc_tbm_dict[mc_corner] = mc_tbm
else:
# TODO
mc_envs = ...
...
dut_params = self._update_dut_params(pinfo,
nbits,
tristate_seg,
seg_buf=seg_buf_final,
seg_inv=inv_seg,
seg_nand=nand_seg,
num_cores=num_cores,
dc_params=delay_cell_params)
mc_results = await self._measure_times(mc_envs,
mc_tbm_dict,
dut_params,
tbm_params,
tbit,
nbits,
name='sim_mc_pre')
mc_factor, sigma_max = self._get_mc_factor(mc_results, td_sigma)
self.log(f'Max std. dev. is {sigma_max}')
self.log(f'Upscale everything by {mc_factor}')
self.log('-' * 80)
# 6. Final verification
seg_unit_final = int(np.ceil(tristate_seg * mc_factor))
seg_unit_final += seg_unit_final & 1 # layout constraint
seg_buf_final = int(np.ceil(seg_buf_final * mc_factor))
seg_buf_final += seg_buf_final & 1 # layout constraint
delay_cell_params_scale = copy.deepcopy(delay_cell_params)
for key in delay_cell_params['seg_dict']:
delay_cell_params_scale['seg_dict'][key] = int(
np.ceil(delay_cell_params['seg_dict'][key] * mc_factor))
nand_seg = int(np.ceil(nand_seg * mc_factor))
inv_seg = int(np.ceil(inv_seg * mc_factor))
dut_params = self._update_dut_params(
pinfo,
nbits,
seg_unit_final,
seg_buf=seg_buf_final,
seg_inv=inv_seg,
seg_nand=nand_seg,
num_cores=num_cores,
dc_params=delay_cell_params_scale)
results = await self._measure_times(dsn_env_names,
tbm_dict,
dut_params,
tbm_params,
tbit,
nbits,
name='sim_sized')
mc_results = await self._measure_times(mc_envs,
mc_tbm_dict,
dut_params,
tbm_params,
tbit,
nbits,
name='sim_mc_post')
_, sigma_max = self._get_mc_factor(mc_results, td_sigma)
self.log(f'Final Sigma: {sigma_max}')
self.log('-' * 80)
else:
seg_unit_final = tristate_seg
delay_cell_params_scale = delay_cell_params
self.log('-' * 80)
self.log(f'dsn_envs: {dsn_env_names}')
self.log(f'final results:\n{pprint.pformat(results, width=100)}')
if plot_result:
from matplotlib import pyplot as plt
plt.figure(1)
ax: Any = plt.subplot(2, 1, 1)
xvec = np.arange(0, results['tdr_step'].shape[1])
for idx, sim_env in enumerate(dsn_env_names):
tdr = results['tdrs'][idx, :-1].flatten()
plt.step(xvec, tdr, where='mid', label=sim_env)
ax.legend()
ax.set_ylabel('Rise Delay (s)')
ax = plt.subplot(2, 1, 2)
for idx, sim_env in enumerate(dsn_env_names):
tdr_step = results['tdr_step'][idx, :].flatten()
ax.scatter(xvec, tdr_step, label=sim_env)
ax.set_ylim(ymin=td_min, ymax=td_max)
ax.legend()
ax.set_ylabel('Rise Delay Step (s)')
ax.set_xlabel('Code')
plt.show()
if gen_specs is not None and gen_cell_args is not None:
gen_cell_specs = dict(
lay_class=IPMarginTemplate.get_qualified_name(),
params=dict(
cls_name=GenericWrapper.get_qualified_name(),
params=dict(
cls_name=PhaseInterpolatorWithDelay.get_qualified_name(
),
params=dut_params,
),
),
**gen_specs,
)
return dict(gen_specs=gen_cell_specs, gen_args=gen_cell_args)
return dict(
seg_unit=seg_unit_final,
seg_buf=seg_buf_final,
seg_dc=delay_cell_params_scale['seg_dict'],
nand_seg=nand_seg,
inv_seg=inv_seg,
)
def design(self, itarg_list, vds2_list, ft_min, stack_list=None):
# type: (List[float], List[float], float, Optional[List[int]]) -> None
"""Design the diode load.
Parameters
----------
itarg_list : List[float]
target single-ended bias current across simulation environments.
vds2_list : List[float]
list of op-amp stage 2 vds voltage across simulation environments.
ft_min : float
minimum transit frequency of the composit transistor.
stack_list : Optional[List[int]]
list of valid stack numbers.
"""
if stack_list is None:
stack_list = self._stack_list
vgs_idx = self._db.get_fun_arg_index('vgs')
num_stack = len(stack_list)
self._best_op = None
best_score = None
for intent in self._intent_list:
for w in self._valid_widths:
for idx1 in range(num_stack):
stack1 = stack_list[idx1]
self._db.set_dsn_params(w=w, intent=intent, stack=stack1)
ib1 = self._db.get_function_list('ibias')
gm1 = self._db.get_function_list('gm')
gds1 = self._db.get_function_list('gds')
cd1 = self._db.get_function_list('cdd')
vgs1_min, vgs1_max = ib1[0].get_input_range(vgs_idx)
for idx2 in range(idx1, num_stack):
stack2 = stack_list[idx2]
self._db.set_dsn_params(stack=stack2)
ib2 = self._db.get_function_list('ibias')
gm2 = self._db.get_function_list('gm')
gds2 = self._db.get_function_list('gds')
cd2 = self._db.get_function_list('cdd')
vgs2_min, vgs2_max = ib2[0].get_input_range(vgs_idx)
vgs_min = max(vgs1_min, vgs2_min)
vgs_max = min(vgs1_max, vgs2_max)
seg1_iter = BinaryIterator(2, None, step=2)
while seg1_iter.has_next():
seg1 = seg1_iter.get_next()
all_neg = True
one_pass = False
seg2_iter = BinaryIterator(0, None, step=2)
while seg2_iter.has_next():
seg2 = seg2_iter.get_next()
vgs_list, err_code = self._solve_vgs(
itarg_list, seg1, seg2, ib1, ib2, vgs_min,
vgs_max)
if err_code < 0:
# too few fingers
seg2_iter.up()
elif err_code > 0:
# too many fingers
seg2_iter.down()
else:
one_pass = True
cur_score = self._compute_score(
ft_min, seg1, seg2, gm1, gm2, gds1,
gds2, cd1, cd2, vgs_list)
if cur_score != -1:
all_neg = False
if cur_score < 0:
seg2_iter.down()
else:
seg2_iter.save()
seg2_iter.up()
if best_score is None or cur_score > best_score:
best_score = cur_score
self._best_op = (intent, stack1,
stack2, w, seg1,
seg2, vgs_list,
vds2_list)
if seg2_iter.get_last_save() is None:
# no solution for seg2
if all_neg and one_pass:
# all solutions encountered have negative resistance,
# this means we have insufficent number of diode fingers.
seg1_iter.up()
elif not one_pass:
# exit immediately with no solutions at all; too many fingers
seg1_iter.down()
else:
# all positive resistance solution break V*_min specs.
# this means we have too many number of fingers.
seg1_iter.down()
else:
seg1_iter.save()
seg1_iter.up()
async def _design_output_inverter(self, inv_in_pseg: int, inv_in_nseg: int,
pseg: int, nseg: int, inv_nseg: int,
inv_pseg: int, out_inv_m: int,
fanout: float, pinfo: Any,
tbm_specs: Dict[str, Any], has_rst, vin,
vout) -> int:
"""
Given all other sizes and total output inverter segments, this function will optimize the output inverter
to minimize rise/fall mismatch.
"""
tb_params = self._get_full_tb_params()
# Use a binary iterator to find the PMOS size
iterator = BinaryIterator(-out_inv_m + 1, out_inv_m - 1)
err_best = float('inf')
all_corners = get_tech_global_info(
'bag3_digital')['signoff_envs']['all_corners']
while iterator.has_next():
pseg_off = iterator.get_next()
dut_params = self._get_lvl_shift_params_dict(pinfo,
pseg,
nseg,
inv_pseg,
inv_nseg,
inv_in_nseg,
inv_in_pseg,
out_inv_m,
has_rst,
dual_output=False,
skew_out=True,
out_pseg_off=pseg_off)
dut = await self.async_new_dut('lvshift', STDCellWrapper,
dut_params)
err_worst = -1 * float('Inf')
worst_env = ''
sim_worst = None
for env in all_corners['envs']:
tbm_specs['sim_envs'] = [env]
tbm_specs['sim_params']['vdd_in'] = all_corners[vin][env]
tbm_specs['sim_params']['vdd'] = all_corners[vout][env]
tbm = cast(CombLogicTimingTB,
self.make_tbm(CombLogicTimingTB, tbm_specs))
sim_results = await self.async_simulate_tbm_obj(
f'sim_output_inv_pseg_{pseg_off}_{env}', dut, tbm,
tb_params)
tdr_cur, tdf_cur = CombLogicTimingTB.get_output_delay(
sim_results.data,
tbm.specs,
'in',
'out',
False,
in_pwr='vdd_in',
out_pwr='vdd')
if math.isinf(np.max(tdr_cur)) or math.isinf(np.max(tdf_cur)):
raise ValueError("Got infinite delay!")
if tdr_cur[0] < 0 or tdf_cur[0] < 0:
raise ValueError("Got negative delay.")
err_cur = np.abs(tdr_cur[0] - tdf_cur[0])
if err_cur > err_worst:
err_worst = err_cur
worst_env = env
tdr = tdr_cur[0]
tdf = tdf_cur[0]
sim_worst = sim_results
'''
print(f'iter: {pseg_off}')
print(f'env: {worst_env}, tdr: {tdr}, tdf: {tdf}')
breakpoint()
'''
if tdr < tdf:
iterator.down(tdr - tdf)
else:
iterator.up(tdr - tdf)
err_abs = np.abs(tdr - tdf)
if err_abs < err_best:
err_best = err_abs
iterator.save_info(pseg_off)
pseg_off = iterator.get_last_save_info()
if pseg_off is None:
raise ValueError("Could not find PMOS size to match target delay")
self.log(f'Calculated output inverter to skew PMOS by {pseg_off}.')
return pseg_off
def find_core_size(
self, # type: ResTech
grid, # type: RoutingGrid
params, # type: Dict[str, Any]
wres, # type: int
hres, # type: int
wblk, # type: int
hblk, # type: int
ext_dir, # type: str
max_blk_ext, # type: int
):
# type: (...) -> Tuple[int, int, Dict[str, Any]]
"""Compute resistor core size that meets DRC rules.
Given current resistor block size and the block pitch, increase the resistor block
size if necessary to meet DRC rules.
Parameters
----------
grid : RoutingGrid
the RoutingGrid object.
params : Dict[str, Any]
the resistor parameters dictionary.
wres : int
resistor core width, in resolution units.
hres : int
resistor core height, in resolution units.
wblk : int
the horizontal block pitch, in resolution units.
hblk : int
the vertical block pitch, in resolution units.
ext_dir : Optional[str]
if equal to 'x', then we will only stretch the resistor core horizontally. If equal
to 'y', we will only stretch the resistor core vertically. Otherwise, we will find
the resistor core with the minimum area that meets the density spec.
max_blk_ext : int
number of block pitches we can extend the resistor core size by. If we cannot
find a valid core size by extending this many block pitches, we declare failure.
Returns
-------
nxblk : int
width of the resistor core, in units of wblk.
nyblk : int
height of the resistor core, in units of hblk.
layout_info : Dict[str, Any]
the core layout information dictionary.
"""
nxblk = wres // wblk
nyblk = hres // hblk
ans = None
x_only = (ext_dir == 'x')
if x_only or (ext_dir == 'y'):
# only extend X or Y direction
if x_only:
bin_iter = BinaryIterator(nxblk, nxblk + max_blk_ext + 1)
else:
bin_iter = BinaryIterator(nyblk, nyblk + max_blk_ext + 1)
while bin_iter.has_next():
ncur = bin_iter.get_next()
if x_only:
wcur, hcur = ncur * wblk, hres
else:
wcur, hcur = wres, ncur * hblk
tmp = self.get_core_info(grid, wcur, hcur, **params)
if tmp is None:
bin_iter.up()
else:
ans = tmp
bin_iter.save()
bin_iter.down()
if ans is None:
raise ValueError(
'failed to find DRC clean core with maximum %d '
'additional block pitches.' % max_blk_ext)
if x_only:
nxblk = bin_iter.get_last_save()
else:
nyblk = bin_iter.get_last_save()
return nxblk, nyblk, ans
else:
# extend in both direction
opt_area = (nxblk + max_blk_ext + 1) * (nyblk + max_blk_ext + 1)
# linear search in height, binary search in width
# in this way, for same area, use height as tie breaker
nxopt, nyopt = nxblk, nyblk
for nycur in range(nyblk, nyblk + max_blk_ext + 1):
# check if we should terminate linear search
if nycur * nxblk >= opt_area:
break
bin_iter = BinaryIterator(nxblk, nxblk + max_blk_ext + 1)
hcur = nycur * hblk
while bin_iter.has_next():
nxcur = bin_iter.get_next()
if nxcur * nycur >= opt_area:
# this point can't beat current optimum
bin_iter.down()
else:
tmp = self.get_core_info(grid, nxcur * wblk, hcur,
**params)
if tmp is None:
bin_iter.up()
else:
# found new optimum
ans, nxopt, nyopt = tmp, nxcur, nycur
opt_area = nxcur * nycur
bin_iter.down()
if ans is None:
raise ValueError(
'failed to find DRC clean core with maximum %d '
'additional block pitches.' % max_blk_ext)
return nxopt, nyopt, ans
def characterize_casc_amp(env_list,
fg_list,
w_list,
db_list,
vbias_list,
vload_list,
vtail_list,
vmid_list,
vcm,
vdd,
vin_max,
cw,
rw,
fanout,
ton,
k_settle_targ,
verr_max,
scale_res=0.1,
scale_min=0.25,
scale_max=20):
# compute DC transfer function curve and compute linearity spec
results = solve_casc_diff_dc(env_list,
db_list,
w_list,
fg_list,
vbias_list,
vload_list,
vtail_list,
vmid_list,
vdd,
vcm,
vin_max,
verr_max,
num_points=20)
vin_vec, vmat_list, verr_list, gain_list = results
# compute settling ratio
fg_in, fg_casc, fg_load = fg_list[1:]
db_in, db_casc, db_load = db_list[1:]
w_in, w_casc, w_load = w_list[1:]
fzin = 1.0 / (2 * ton)
wzin = 2 * np.pi * fzin
tvec = np.linspace(0, ton, 200, endpoint=True)
scale_list = []
for env, vload, vtail, vmid in zip(env_list, vload_list, vtail_list,
vmid_list):
# step 1: construct half circuit
in_params = db_in.query(env=env,
w=w_in,
vbs=-vtail,
vds=vmid - vtail,
vgs=vcm - vtail)
casc_params = db_casc.query(env=env,
w=w_casc,
vbs=-vmid,
vds=vcm - vmid,
vgs=vdd - vmid)
load_params = db_load.query(env=env,
w=w_load,
vbs=0,
vds=vcm - vdd,
vgs=vload - vdd)
circuit = LTICircuit()
circuit.add_transistor(in_params, 'mid', 'in', 'gnd', fg=fg_in)
circuit.add_transistor(casc_params, 'd', 'gnd', 'mid', fg=fg_casc)
circuit.add_transistor(load_params, 'd', 'gnd', 'gnd', fg=fg_load)
# step 2: get input capacitance
zin = circuit.get_impedance('in', fzin)
cin = (1 / zin).imag / wzin
circuit.add_cap(cin * fanout, 'out', 'gnd')
# step 3: find scale factor to achieve k_settle
bin_iter = BinaryIterator(scale_min,
None,
step=scale_res,
is_float=True)
while bin_iter.has_next():
# add scaled wired parasitics
cur_scale = bin_iter.get_next()
cap_cur = cw / 2 / cur_scale
res_cur = rw * cur_scale
circuit.add_cap(cap_cur, 'd', 'gnd')
circuit.add_cap(cap_cur, 'out', 'gnd')
circuit.add_res(res_cur, 'd', 'out')
# get settling factor
sys = circuit.get_voltage_gain_system('in', 'out')
dc_gain = sys.freqresp(w=np.array([0.1]))[1][0]
sgn = 1 if dc_gain.real >= 0 else -1
dc_gain = abs(dc_gain)
_, yvec = scipy.signal.step(
sys, T=tvec) # type: Tuple[np.ndarray, np.ndarray]
k_settle_cur = 1 - abs(yvec[-1] - sgn * dc_gain) / dc_gain
print('scale = %.4g, k_settle = %.4g' % (cur_scale, k_settle_cur))
# update next scale factor
if k_settle_cur >= k_settle_targ:
print('save scale = %.4g' % cur_scale)
bin_iter.save()
bin_iter.down()
else:
if cur_scale > scale_max:
raise ValueError(
'cannot meet settling time spec at scale = %d' %
cur_scale)
bin_iter.up()
# remove wire parasitics
circuit.add_cap(-cap_cur, 'd', 'gnd')
circuit.add_cap(-cap_cur, 'out', 'gnd')
circuit.add_res(-res_cur, 'd', 'out')
scale_list.append(bin_iter.get_last_save())
return vmat_list, verr_list, gain_list, scale_list
def draw_layout(self):
# type: () -> None
w = self.params['w']
h_unit = self.params['h_unit']
narr = self.params['narr']
sub_type = self.params['sub_type']
threshold = self.params['threshold']
top_layer = self.params['top_layer']
nser = self.params['nser']
ndum = self.params['ndum']
port_tr_w = self.params['port_tr_w']
res_type = self.params['res_type']
res_options = self.params['res_options']
cap_spx = self.params['cap_spx']
cap_spy = self.params['cap_spy']
cap_h_list = self.params['cap_h_list']
half_blk_x = self.params['half_blk_x']
show_pins = self.params['show_pins']
if nser % 2 != 0:
raise ValueError('This generator only supports even nser.')
res = self.grid.resolution
lay_unit = self.grid.layout_unit
w_unit = int(round(w / lay_unit / res))
if res_options is None:
my_options = dict(well_end_mode=2)
else:
my_options = res_options.copy()
my_options['well_end_mode'] = 2
# find resistor length
info = ResArrayBaseInfo(self.grid,
sub_type,
threshold,
top_layer=top_layer,
res_type=res_type,
ext_dir='y',
options=my_options,
connect_up=True,
half_blk_x=half_blk_x,
half_blk_y=True)
lmin, lmax = info.get_res_length_bounds()
bin_iter = BinaryIterator(lmin, lmax, step=2)
while bin_iter.has_next():
lcur = bin_iter.get_next()
htot = info.get_place_info(lcur, w_unit, 1, 1)[3]
if htot < h_unit:
bin_iter.save()
bin_iter.up()
else:
bin_iter.down()
# draw resistor
l_unit = bin_iter.get_last_save()
nx = 2 * ndum + narr * nser
self.draw_array(l_unit * lay_unit * res,
w,
sub_type,
threshold,
nx=nx,
ny=1,
top_layer=top_layer,
res_type=res_type,
grid_type=None,
ext_dir='y',
options=my_options,
connect_up=True,
half_blk_x=half_blk_x,
half_blk_y=True,
min_height=h_unit)
# get cap settings
bot_layer = self.bot_layer_id + 1
for lay in range(bot_layer, top_layer + 1):
if self.grid.get_direction(lay) == 'x':
cap_spx = max(
cap_spx,
self.grid.get_line_end_space(lay, 1, unit_mode=True))
# connect resistors and draw MOM caps
tmp = self._connect_resistors(narr, nser, ndum, cap_spx, port_tr_w,
show_pins)
rout_list, cap_x_list = tmp
tmp = self._draw_mom_cap(cap_x_list, bot_layer, top_layer, cap_spy,
cap_h_list, port_tr_w, show_pins)
cout_list, ores_info, cres_info = tmp
# connect bias resistor to cap
for rout, cout in zip(rout_list, cout_list):
self.connect_to_track_wires(rout, cout)
# set schematic parameters
self._sch_params = dict(
narr=narr,
ndum=ndum * 2,
hp_params=dict(
l=l_unit * lay_unit * res,
w=w,
intent=res_type,
nser=nser,
ndum=0,
res_in_info=cres_info,
res_out_info=ores_info,
sub_name='VSS',
),
)
def fill_symmetric_min_density_info(area: int,
n_min: int,
n_max: int,
sp_min: int,
area_specs: List[Tuple[int, int, int]],
sp_max: Optional[int] = None,
fill_on_edge: bool = True,
cyclic: bool = False) -> FillInfo:
"""Fill the given 1-D area to satisfy minimum density constraint
Compute fill location such that the given area is filled with the following properties:
1. the area is as uniform as possible.
2. the area is symmetric with respect to the center
3. all fill blocks have lengths between n_min and n_max.
4. all fill blocks are at least sp_min apart.
Parameters
----------
area : int
total number of space we need to fill.
n_min : int
minimum length of the fill block. Must be less than or equal to n_max.
n_max : int
maximum length of the fill block.
sp_min : int
minimum space between each fill block.
area_specs : List[Tuple[int, int, int]]
list of area specifications, in (target, scale, extension) format.
sp_max : Optional[int]
if given, make sure space between blocks does not exceed this value.
Must be greater than sp_min
fill_on_edge : bool
If True, we put fill blocks on area boundary. Otherwise, we put space block on
area boundary.
cyclic : bool
If True, we assume we're filling in a cyclic area (it wraps around).
Returns
-------
info : FillInfo
the fill information object.
"""
# first, fill as much as possible using scale/extension of the first area spec.
max_result = fill_symmetric_max_density_info(area,
n_min,
n_max,
sp_min,
area_specs,
sp_max=sp_max,
fill_on_edge=fill_on_edge,
cyclic=cyclic)
if not max_result.meet_area_specs(area_specs):
# we cannot meet area spec; return max result
return max_result
# now, reduce fill by doing binary search on n_max
nfill_opt = max_result.num_fill
n_max_iter = BinaryIterator(n_min, n_max)
while n_max_iter.has_next():
n_max_cur = n_max_iter.get_next()
try:
info = fill_symmetric_max_num_info(area,
nfill_opt,
n_min,
n_max_cur,
sp_min,
fill_on_edge=fill_on_edge,
cyclic=cyclic)
if info.meet_area_specs(area_specs) and (sp_max is None
or info.sp_max <= sp_max):
# both specs passed
n_max_iter.save_info(info)
n_max_iter.down()
else:
# reduce n_max too much
n_max_iter.up()
except ValueError:
# get here if n_min == n_max and there's no solution.
n_max_iter.up()
last_save = n_max_iter.get_last_save_info()
if last_save is None:
# no solution, return max result
return max_result
else:
max_result = last_save
# see if we can further reduce fill by doing binary search on nfill_opt
nfill_iter = BinaryIterator(1, nfill_opt)
n_max = n_max_iter.get_last_save()
while nfill_iter.has_next():
nfill_cur = nfill_iter.get_next()
try:
info = fill_symmetric_max_num_info(area,
nfill_cur,
n_min,
n_max,
sp_min,
fill_on_edge=fill_on_edge,
cyclic=cyclic)
if info.meet_area_specs(area_specs) and (sp_max is None
or info.sp_max <= sp_max):
# both specs passed
nfill_iter.save_info(info)
nfill_iter.down()
else:
# reduce nfill too much
nfill_iter.up()
except ValueError:
nfill_iter.up()
last_save = nfill_iter.get_last_save_info()
if last_save is None:
return max_result
# return new minimum solution
return last_save
def draw_layout(self):
# type: () -> None
w = self.params['w']
h_unit = self.params['h_unit']
sub_type = self.params['sub_type']
threshold = self.params['threshold']
top_layer = self.params['top_layer']
nser = self.params['nser']
ndum = self.params['ndum']
in_tr_info = self.params['in_tr_info']
out_tr_info = self.params['out_tr_info']
bias_idx = self.params['bias_idx']
vdd_tr_info = self.params['vdd_tr_info']
res_type = self.params['res_type']
res_options = self.params['res_options']
cap_spx = self.params['cap_spx']
cap_spy = self.params['cap_spy']
cap_margin = self.params['cap_margin']
half_blk_x = self.params['half_blk_x']
show_pins = self.params['show_pins']
res = self.grid.resolution
lay_unit = self.grid.layout_unit
w_unit = int(round(w / lay_unit / res))
if res_options is None:
my_options = dict(well_end_mode=2)
else:
my_options = res_options.copy()
my_options['well_end_mode'] = 2
# find resistor length
info = ResArrayBaseInfo(self.grid,
sub_type,
threshold,
top_layer=top_layer,
res_type=res_type,
grid_type=None,
ext_dir='y',
options=my_options,
connect_up=True,
half_blk_x=half_blk_x,
half_blk_y=True)
lmin, lmax = info.get_res_length_bounds()
bin_iter = BinaryIterator(lmin, lmax, step=2)
while bin_iter.has_next():
lcur = bin_iter.get_next()
htot = info.get_place_info(lcur, w_unit, 1, 1)[3]
if htot < h_unit:
bin_iter.save()
bin_iter.up()
else:
bin_iter.down()
# draw resistor
l_unit = bin_iter.get_last_save()
nx = 2 * (nser + ndum)
self.draw_array(l_unit * lay_unit * res,
w,
sub_type,
threshold,
nx=nx,
ny=1,
top_layer=top_layer,
res_type=res_type,
grid_type=None,
ext_dir='y',
options=my_options,
connect_up=True,
half_blk_x=half_blk_x,
half_blk_y=True,
min_height=h_unit)
# connect resistors
vdd, biasp, biasn, outp_h, outn_h, xl, xr = self.connect_resistors(
ndum, nser, bias_idx)
# draw MOM cap
caplp, capln, caprp, caprn = self.draw_mom_cap(nser, xl, xr, cap_spx,
cap_spy, cap_margin)
# connect resistors to MOM cap, and draw metal resistors
vm_layer = self.bot_layer_id + 1
self.connect_to_tracks(outp_h, capln.track_id)
self.connect_to_tracks(outn_h, caprn.track_id)
# connect outputs to horizontal tracks
hm_layer = vm_layer + 1
pidx, nidx, tr_w = in_tr_info
res_in_w = self.grid.get_track_width(hm_layer, tr_w, unit_mode=True)
inp, inn = self.connect_differential_tracks(caplp,
caprp,
hm_layer,
pidx,
nidx,
width=tr_w)
tr_lower, tr_upper = inp.lower_unit, inp.upper_unit
self.add_res_metal_warr(hm_layer,
pidx,
tr_lower - res_in_w,
tr_lower,
width=tr_w,
unit_mode=True)
self.add_res_metal_warr(hm_layer,
nidx,
tr_lower - res_in_w,
tr_lower,
width=tr_w,
unit_mode=True)
inp = self.add_wires(hm_layer,
pidx,
tr_lower - 2 * res_in_w,
tr_lower - res_in_w,
width=tr_w,
unit_mode=True)
inn = self.add_wires(hm_layer,
nidx,
tr_lower - 2 * res_in_w,
tr_lower - res_in_w,
width=tr_w,
unit_mode=True)
pidx, nidx, tr_w = out_tr_info
res_out_w = self.grid.get_track_width(hm_layer, tr_w, unit_mode=True)
self.connect_differential_tracks(capln,
caprn,
hm_layer,
pidx,
nidx,
track_lower=tr_lower,
track_upper=tr_upper,
width=tr_w,
unit_mode=True)
self.add_res_metal_warr(hm_layer,
pidx,
tr_upper,
tr_upper + res_out_w,
width=tr_w,
unit_mode=True)
self.add_res_metal_warr(hm_layer,
nidx,
tr_upper,
tr_upper + res_out_w,
width=tr_w,
unit_mode=True)
outp = self.add_wires(hm_layer,
pidx,
tr_upper + res_out_w,
tr_upper + 2 * res_out_w,
width=tr_w,
unit_mode=True)
outn = self.add_wires(hm_layer,
nidx,
tr_upper + res_out_w,
tr_upper + 2 * res_out_w,
width=tr_w,
unit_mode=True)
# connect/export vdd
if vdd_tr_info is None:
self.add_pin('VDD_vm', vdd, label='VDD:', show=show_pins)
else:
self.add_pin('VDD_vm', vdd, label='VDD', show=show_pins)
for tr_info in vdd_tr_info:
tid = TrackID(hm_layer, tr_info[0], width=tr_info[1])
self.add_pin('VDD',
self.connect_to_tracks(vdd, tid),
show=show_pins)
# add pins
self.add_pin('biasp', biasp, show=show_pins)
self.add_pin('biasn', biasn, show=show_pins)
self.add_pin('outp', outp, show=show_pins)
self.add_pin('outn', outn, show=show_pins)
self.add_pin('inp', inp, show=show_pins)
self.add_pin('inn', inn, show=show_pins)
self._sch_params = dict(
l=l_unit * lay_unit * res,
w=w,
intent=res_type,
nser=nser,
ndum=ndum,
res_in_info=(hm_layer, res_in_w * res * lay_unit,
res_in_w * res * lay_unit),
res_out_info=(hm_layer, res_out_w * res * lay_unit,
res_out_w * res * lay_unit),
)
def design(
self,
i1_unit, # type: List[float]
i1_min_size, # type: int
vg_list, # type: List[float]
vout_list, # type: List[float]
cpar1, # type: float
cload, # type: float
f_unit, # type: float
phase_margin, # type: float
res_var, # type: float
l, # type: float
vstar_gm_min, # type: float
ft_load_scale, # type: float
vds_tail_min, # type: float
seg_gm_min, # type: int
vdd, # type: float
pmos_input=True, # type: bool
max_ref_ratio=20, # type: int
load_stack_list=None, # type: Optional[List[int]]
):
# type: (...) -> None
# binary search for minimum stage 1 current,
i1_size_iter = BinaryIterator(i1_min_size, None)
i1_size_opt, opt_info = None, None
while i1_size_iter.has_next():
i1_size = i1_size_iter.get_next()
print('trying i1_size = %d' % i1_size)
try:
self._design_with_itarg(i1_size, i1_unit, vg_list, vout_list,
cpar1, cload, f_unit, phase_margin,
res_var, l, vstar_gm_min,
ft_load_scale, vds_tail_min,
seg_gm_min, vdd, pmos_input,
max_ref_ratio, load_stack_list)
success = True
except StageOneCurrentError as err:
print(err)
success = False
if success:
print('success')
opt_info = self._amp_info
i1_size_opt = i1_size
i1_size_iter.down()
else:
i1_size_iter.up()
# linear search to find optimal scale2
scale2_int_max = int(opt_info['scale2'])
if scale2_int_max == opt_info['scale2']:
scale2_int_max -= 1
last_i1_size = i1_size_opt
print('i1_size = %d, scale2 = %.4g' %
(i1_size_opt, opt_info['scale2']))
for scale2_test in range(scale2_int_max, 0, -1):
i1_size_test = int(
np.floor(i1_size_opt * (1 + opt_info['scale2']) /
(1 + scale2_test)))
if i1_size_test <= last_i1_size or scale2_test == opt_info[
'scale2']:
continue
print('testing i1_size = %d, scale2 = %.4g' %
(i1_size_test, scale2_test))
try:
self._design_with_itarg(i1_size_test, i1_unit, vg_list,
vout_list, cpar1, cload, f_unit,
phase_margin, res_var, l, vstar_gm_min,
ft_load_scale, vds_tail_min,
seg_gm_min, vdd, pmos_input,
max_ref_ratio, load_stack_list)
except StageOneCurrentError as err:
print(err)
continue
if self._amp_info['scale2'] <= scale2_test:
# found new minimum. close in to find optimal i1 size
opt_info = self._amp_info
i1_size_opt = i1_size_test
print('update: i1_size = %d, scale2 = %.4g' %
(i1_size_opt, opt_info['scale2']))
i1_size_iter = BinaryIterator(last_i1_size + 1, i1_size_test)
while i1_size_iter.has_next():
i1_size_cur_opt = i1_size_iter.get_next()
print('testing i1_size = %d' % i1_size_cur_opt)
try:
self._design_with_itarg(i1_size_cur_opt, i1_unit,
vg_list, vout_list, cpar1,
cload, f_unit, phase_margin,
res_var, l, vstar_gm_min,
ft_load_scale, vds_tail_min,
seg_gm_min, vdd, pmos_input,
max_ref_ratio, load_stack_list)
if self._amp_info['scale2'] <= opt_info['scale2']:
opt_info = self._amp_info
i1_size_opt = i1_size_cur_opt
print('update: i1_size = %d, '
'scale2 = %.4g' %
(i1_size_opt, opt_info['scale2']))
i1_size_iter.down()
else:
i1_size_iter.up()
except StageOneCurrentError as err:
print(err)
i1_size_iter.up()
last_i1_size = i1_size_test
self._amp_info = opt_info
def _design_stage2(self, gm_db, load_db, vtail_list, vg_list, vmid_list,
vout_list, vbias_list, vb_gm, vb_load, cload, cpar1,
w_dict, th_dict, stack_dict, seg_dict, gm2_list,
res_var, phase_margin, f_unit, max_ref_ratio):
seg_tail1 = seg_dict['tail1']
seg_diode1 = seg_dict['diode1']
seg_ngm1 = seg_dict['ngm1']
# step 1: find stage 2 unit size
seg_gcd = gcd(gcd(seg_tail1, seg_diode1), seg_ngm1)
if seg_gcd % 2 != 0:
raise ValueError('All segment numbers must be even.')
# divide seg_gcd by 2 to make sure all generated segment numbers are even
seg_gcd //= 2
# make sure we have enough tail fingers for common mode feedback
min_size = 2 if seg_tail1 // seg_gcd == 2 else 1
def ac_results_fun(cur_size):
seg_dict['tail2'] = seg_tail1 // seg_gcd * cur_size
seg_dict['diode2'] = seg_diode1 // seg_gcd * cur_size
seg_dict['ngm2'] = seg_ngm1 // seg_gcd * cur_size
cur_scale2 = cur_size / seg_gcd
cur_gm2_list = [gm2 * cur_scale2 for gm2 in gm2_list]
ac_results = self._find_rz_cf(gm_db, load_db, vtail_list, vg_list,
vmid_list, vout_list, vbias_list,
vb_gm, vb_load, cload, cpar1, w_dict,
th_dict, stack_dict, seg_dict,
cur_gm2_list, res_var, phase_margin)
return ac_results
def funity_fun(cur_size):
ac_results_tmp = ac_results_fun(cur_size)
fu_list = ac_results_tmp[0]
if fu_list is None:
return -1
# noinspection PyTypeChecker
ans = min(fu_list)
return ans
# find min_size such that amplifier is stable
min_bin_iter = BinaryIterator(min_size, None)
while min_bin_iter.has_next():
test_size = min_bin_iter.get_next()
test_fu = funity_fun(test_size)
if test_fu >= 0:
min_bin_iter.save()
min_bin_iter.down()
else:
min_bin_iter.up()
min_result = minimize_cost_golden(funity_fun,
f_unit,
offset=min_bin_iter.get_last_save())
if min_result.x is None:
msg = 'Insufficient stage 1 current. funity_max=%.4g'
raise StageOneCurrentError(msg % min_result.vmax)
funity_list, rz_nom, cf_min, gain_list, f3db_list, pm_list = ac_results_fun(
min_result.x)
seg_tail2_tot = seg_dict['tail2']
seg_tail2 = (seg_tail2_tot // 4) * 2
seg_tailcm = seg_tail2_tot - seg_tail2
seg_tail_tot = 2 * (seg_dict['tail1'] + seg_tail2)
seg_dict['tail2'] = seg_tail2
seg_dict['tailcm'] = seg_tailcm
seg_dict['ref'] = max(2, -((-seg_tail_tot // max_ref_ratio) // 2) * 2)
return dict(
rz=rz_nom,
cf=cf_min,
gain=gain_list,
f_3db=f3db_list,
f_unity=funity_list,
phase_margin=pm_list,
)
def fill_symmetric_min_density_info(area,
targ_area,
n_min,
n_max,
sp_min,
sp_max=None,
fill_on_edge=True,
cyclic=False):
# type: (int, int, int, int, int, Optional[int], bool, bool) -> Tuple[Tuple[Any, ...], bool]
"""Fill the given 1-D area as little as possible.
Compute fill location such that the given area is filled with the following properties:
1. the area is as uniform as possible.
2. the area is symmetric with respect to the center
3. all fill blocks have lengths between n_min and n_max.
4. all fill blocks are at least sp_min apart.
Parameters
----------
area : int
total number of space we need to fill.
targ_area : int
target minimum fill area. If not achievable, will do the best that we can.
n_min : int
minimum length of the fill block. Must be less than or equal to n_max.
n_max : int
maximum length of the fill block.
sp_min : int
minimum space between each fill block.
sp_max : Optional[int]
if given, make sure space between blocks does not exceed this value.
Must be greater than sp_min
fill_on_edge : bool
If True, we put fill blocks on area boundary. Otherwise, we put space block on
area boundary.
cyclic : bool
If True, we assume we're filling in a cyclic area (it wraps around).
Returns
-------
info : Tuple[Any, ...]
the fill information tuple.
invert : bool
True if space/fill is inverted.
"""
# first, fill as much as possible
max_result = fill_symmetric_max_density_info(area,
targ_area,
n_min,
n_max,
sp_min,
sp_max=sp_max,
fill_on_edge=fill_on_edge,
cyclic=cyclic)
fill_area, nfill_opt = max_result[0][:2]
if fill_area <= targ_area:
# we cannot/barely meet area spec; return max result
return max_result
# now, reduce fill by doing binary search on n_max
n_max_iter = BinaryIterator(n_min, n_max)
while n_max_iter.has_next():
n_max_cur = n_max_iter.get_next()
try:
info, invert = fill_symmetric_max_num_info(
area,
nfill_opt,
n_min,
n_max_cur,
sp_min,
fill_on_edge=fill_on_edge,
cyclic=cyclic)
fill_area_cur = area - info[0] if invert else info[0]
if invert:
_, sp_cur = _get_min_max_blk_len(info)
else:
sp_cur = sp_min if info[1][2] == 0 else sp_min + 1
if fill_area_cur >= targ_area and (sp_max is None
or sp_cur <= sp_max):
# both specs passed
n_max_iter.save_info((info, invert))
n_max_iter.down()
else:
# reduce n_max too much
n_max_iter.up()
except ValueError:
# get here if n_min == n_max and there's no solution.
n_max_iter.up()
last_save = n_max_iter.get_last_save_info()
if last_save is None:
# no solution, return max result
return max_result
# return new minimum solution
info, invert = last_save
fill_area = area - info[0] if invert else info[0]
return (fill_area, nfill_opt, info[1]), invert
async def _design_lvl_shift_inv_pun(self, pseg: int, nseg: int,
inv_nseg: int, out_inv_m: int,
fanout: float, pinfo: Any,
tbm_specs: Dict[str, Any], has_rst,
dual_output, vin,
vout) -> Tuple[int, int]:
"""
Given the NMOS pull down size, this function will design the PMOS pull up so that the delay
mismatch is minimized.
"""
inv_beta = get_tech_global_info('bag3_digital')['inv_beta']
tb_params = self._get_full_tb_params()
# Use a binary iterator to find the PMOS size
load_seg = nseg + (pseg if has_rst else 0)
inv_pseg_nom = int(
np.round(inv_beta * load_seg / ((1 + inv_beta) * fanout)))
inv_pseg_nom = 1 if inv_pseg_nom == 0 else inv_pseg_nom
inv_nseg_nom = inv_nseg # save the value of nseg coming into this function as nominal
range_to_vary = min(inv_pseg_nom, inv_nseg)
iterator = BinaryIterator(
-range_to_vary + 1,
1) # upper limit is exclusive hence using 1 instead of 0
# variation will be done such that the total P+N segments remains the same
# This allows the input inverter sizing to be done once at the start
# iterator = BinaryIterator(-inv_pseg_nom+1, 0)
# iterator = BinaryIteratorInterval(get_tech_global_info('bag3_digital')['width_interval_list_p'],
# -inv_pseg_nom+1, 0)
err_best = float('inf')
inv_in_nseg, inv_in_pseg = self._size_input_inv_for_fanout(
inv_pseg_nom, inv_nseg, pseg, nseg, fanout, has_rst)
all_corners = get_tech_global_info(
'bag3_digital')['signoff_envs']['all_corners']
while iterator.has_next():
pseg_off = iterator.get_next()
inv_pseg = inv_pseg_nom + pseg_off
inv_nseg = inv_nseg_nom - pseg_off
dut_params = self._get_lvl_shift_params_dict(
pinfo, pseg, nseg, inv_pseg, inv_nseg, inv_in_pseg,
inv_in_nseg, out_inv_m, has_rst, dual_output)
dut = await self.async_new_dut('lvshift', STDCellWrapper,
dut_params)
err_worst = -1 * float('Inf')
for env in all_corners['envs']:
tbm_specs['sim_envs'] = [env]
tbm_specs['sim_params']['vdd_in'] = all_corners[vin][env]
tbm_specs['sim_params']['vdd'] = all_corners[vout][env]
tbm = cast(CombLogicTimingTB,
self.make_tbm(CombLogicTimingTB, tbm_specs))
sim_results = await self.async_simulate_tbm_obj(
f'sim_inv_pseg_{inv_pseg}_{env}', dut, tbm, tb_params)
tdr_cur, tdf_cur = CombLogicTimingTB.get_output_delay(
sim_results.data,
tbm.specs,
'in',
'out',
False,
in_pwr='vdd_in',
out_pwr='vdd')
print("Balance rise/fall delays inv_pup Info: ", env, tdr_cur,
tdf_cur)
# Error checking
if math.isinf(np.max(tdr_cur)) or math.isinf(np.max(tdf_cur)):
raise ValueError("Got infinite delay!")
if np.min(tdr_cur) < 0 or np.min(tdf_cur) < 0:
raise ValueError("Got negative delay.")
err_cur = np.abs(tdr_cur[0] - tdf_cur[0])
if err_cur > err_worst:
err_worst = err_cur
worst_env = env
tdr = tdr_cur[0]
tdf = tdf_cur[0]
if tdr < tdf:
iterator.down(tdr - tdf)
else:
iterator.up(tdr - tdf)
err_abs = np.abs(tdr - tdf)
if err_abs < err_best:
err_best = err_abs
iterator.save_info(pseg_off)
pseg_off = iterator.get_last_save_info()
pseg_off = 0 if pseg_off is None else pseg_off # Should only hit this case if inv_pseg_nom = 1
inv_pseg = inv_pseg_nom + pseg_off
inv_nseg = inv_nseg_nom - pseg_off
return inv_pseg, inv_nseg - 0 * pseg_off