def __init__(self, iNode, pwrNode, gndNode, model, speed=Typical):
"""
Arguments:
iNode -- Input Node
pwrNode -- Vcc Node
gndNode -- Ground Node
model -- IbisModel
speed -- (optional) Maximum, Minimum, Typical, default = Typical
"""
self.__dict__['model'] = model
self.__dict__['speed'] = speed
if hasattr(model, 'c_comp'):
self.C_comp = device.C(iNode, gndNode, model.c_comp[speed])
if hasattr(model, 'gnd_clamp'):
self.VI_gnd = device.VI(iNode, gndNode,
waveform.PWL(model.gnd_clamp[speed]))
if hasattr(model, 'power_clamp'):
self.VI_pwr = device.VI(pwrNode, iNode,
waveform.PWL(model.power_clamp[speed]))
def __init__(self,
oNode,
pwrNode,
gndNode,
model,
speed=Typical,
direction=Rising):
"""
Arguments:
oNode -- Output Node
pwrNode -- Vcc Node
gndNode -- Ground Node
model -- IbisModel
speed -- (optional) Maximum, Minimum, or Typical, default = Typical
direction -- (optional) Rising or Falling, default = Rising
"""
self.__dict__['model'] = model
self.__dict__['speed'] = speed
self.__dict__['direction'] = direction
if hasattr(model, 'c_comp'):
self.C_comp = device.C(oNode, gndNode, model.c_comp[speed])
if hasattr(model, 'gnd_clamp'):
self.VI_gnd = device.VI(oNode, gndNode,
waveform.PWL(model.gnd_clamp[speed]))
if hasattr(model, 'power_clamp'):
self.VI_pwr = device.VI(pwrNode, oNode,
waveform.PWL(model.power_clamp[speed]))
if hasattr(model, 'pullup'):
self.VI_pu = device.VI(
pwrNode, oNode, waveform.PWL(model.pullup[speed]),
waveform.PWL(model.pullup_k[direction][speed]))
if hasattr(model, 'pulldown'):
self.VI_pd = device.VI(
oNode, gndNode, waveform.PWL(model.pulldown[speed]),
waveform.PWL(model.pulldown_k[direction][speed]))
def calcDriverKDoubleWave(model, direction, speed, tstepDivisor=10):
"""
Calculates a Time/Multiplier (TA) Table using 2 Waveforms
Arguments:
model -- IBIS Model Class
direction -- either Rising or Falling (constants defined above)
speed -- either Typical, Maximum, or Minimum (constants defined above)
tstepDivisor -- Number of simulation points between defined waveform
points, a larger number may yeild a more accurate result but will
take longer to process.
Returns:
(ku, kd) -- two 2D Arrays, the first column in each is time and the
second is either the up (ku) or down (kd) VI Multiplier
To create an IBIS Defined Driver Model that changes state the Driver's
two VI Tables (Pull-Up and Pull-Down) are modified during the simulation
by multiplying them at each time step with values from the TA Tables.
This method of calculating a Driver TA Table is the most accuarate.
It uses two provided Waveforms driven into two different loads. This
function uses the eispice simulation engine to simulate two instanciations
of the follow circuit:
VCC VCC
+ +
| | Power Clamp IV
.-. Pull-Up IV .-. (Xcu0/1)
| | (Xpu0/1) | |
| | | | Vfixture
.-----. '-' _ Current Probe '-' +
| G | | / \ (Vmeas) | ___ |
|_-_-_|----------(_/_)--------o-----------o----|___|--o
| | | \_/ | | Rfixture
'-----' .-. | .-.
Waveform | | Pull-Down IV --- C_comp | | Ground Clamp IV
(Xwv0/1) | | (Xpd0/1) --- (Cc0/1) | | (Xcd0/1)
'-' | '-'
| | |
=== === ===
GND GND GND
The value of the two multipliers (ku and ku) are calculated at
each time step using a two B-Elements, based on the folowing relationships:
Imeas0 = ku*Ipu0 - kd*Ipd0 (1)
Imeas1 = ku*Ipu1 - kd*Ipd1 (2)
Solving (1) for ku:
Imeas0 - kd*Ipd0
ku = ----------------- (3)
Ipu0
Substitute into (2) and solving results in:
Imeas0*Ipu1 - Imeas1*Ipu0
kd = ------------------------- (4)
Ipd1*Ipu0 - Ipd0*Ipu1
To limit calculation error the paired releationship is used to
calculate ku, not (3):
Imeas0*Ipd1 - Imeas1*Ipd0
ku = ------------------------- (5)
Ipd1*Ipu0 - Ipd0*Ipu1
"""
if direction == Rising:
wave = model.rising_waveform
elif direction == Falling:
wave = model.falling_waveform
else:
raise RuntimeError, 'Direction must be Rising or Falling.'
# Based on the schematic defined above
cct = circuit.Circuit("Double Waveform")
# ----------------------- Waveform 0 -----------------------------------
cct.Vcc = device.V('vcc', 0, model.voltage_range[speed])
cct.Xwv0 = device.V('wv0', 0, 0, waveform.PWL(wave[0].data[speed]))
cct.Xpu0 = device.VI('vcc', 'wv0', waveform.PWL(model.pullup[speed]))
cct.Xpd0 = device.VI('wv0', 0, waveform.PWL(model.pulldown[speed]))
cct.Vmeas0 = device.V('wv0', 'ts0', 0)
cct.Cc0 = device.C('ts0', 0, model.c_comp[speed])
cct.Rfix0 = device.R('ts0', 'fix0', wave[0].r_fixture)
if speed == Typical:
cct.Vfix0 = device.V('fix0', 0, wave[0].v_fixture)
elif speed == Maximum:
try:
cct.Vfix0 = device.V('fix0', 0, wave[0].v_fixture_min)
except AttributeError:
cct.Vfix0 = device.V('fix0', 0, wave[0].v_fixture)
elif speed == Minimum:
try:
cct.Vfix0 = device.V('fix0', 0, wave[0].v_fixture_max)
except AttributeError:
cct.Vfix0 = device.V('fix0', 0, wave[0].v_fixture)
# May not have GND and/or Power Clamps
if hasattr(model, 'power_clamp'):
cct.Xcu0 = device.VI('vcc', 'ts0',
waveform.PWL(model.power_clamp[speed]))
if hasattr(model, 'gnd_clamp'):
cct.Xcd0 = device.VI('ts0', 0, waveform.PWL(model.gnd_clamp[speed]))
# ----------------------- Waveform 1 -----------------------------------
cct.Xwv1 = device.V('wv1', 0, 0, waveform.PWL(wave[1].data[speed]))
cct.Xpu1 = device.VI('vcc', 'wv1', waveform.PWL(model.pullup[speed]))
cct.Xpd1 = device.VI('wv1', 0, waveform.PWL(model.pulldown[speed]))
cct.Vmeas1 = device.V('wv1', 'ts1', 0)
cct.Cc1 = device.C('ts1', 0, model.c_comp[speed])
cct.Rfix1 = device.R('ts1', 'fix1', wave[1].r_fixture)
if speed == Typical:
cct.Vfix1 = device.V('fix1', 0, wave[1].v_fixture)
elif speed == Maximum:
try:
cct.Vfix1 = device.V('fix1', 0, wave[1].v_fixture_min)
except AttributeError:
cct.Vfix1 = device.V('fix1', 0, wave[1].v_fixture)
elif speed == Minimum:
try:
cct.Vfix1 = device.V('fix1', 0, wave[1].v_fixture_max)
except AttributeError:
cct.Vfix1 = device.V('fix1', 0, wave[1].v_fixture)
# May not have GND and/or Power Clamps
if hasattr(model, 'power_clamp'):
cct.Xcu1 = device.VI('vcc', 'ts1',
waveform.PWL(model.power_clamp[speed]))
if hasattr(model, 'gnd_clamp'):
cct.Xcd1 = device.VI('ts1', 0, waveform.PWL(model.gnd_clamp[speed]))
# ------------------ Multiplier Calculator -----------------------------
# Equation (4)
cct.Bkdn = device.B(
'kd', 0, 'v', "(i(Xpu0)*i(Vmeas1) - i(Xpu1)*i(Vmeas0))"
"/ (i(Xpd0)*i(Xpu1) - i(Xpd1)*i(Xpu0))")
# Equation (5)
cct.Bkun = device.B(
'ku', 0, 'v', "(i(Xpd0)*i(Vmeas1) - i(Xpd1)*i(Vmeas0))"
"/ (i(Xpd0)*i(Xpu1) - i(Xpd1)*i(Xpu0))")
# The simulation length is based on the last time point from the longest
# defined waverform.
tstop0 = wave[0].data[speed][wave[0].data[speed].shape[0] - 1][0]
tstop1 = wave[1].data[speed][wave[1].data[speed].shape[0] - 1][0]
tstop = max(tstop0, tstop1)
# The simulation step length is based on the shortest step between points
# 0 and 1.
tstep0 = wave[0].data[speed][1][0] - wave[0].data[speed][0][0]
tstep1 = wave[1].data[speed][1][0] - wave[1].data[speed][0][0]
tstep = min(tstep0, tstep1)
# Run the simulations
cct.tran(tstep / tstepDivisor, tstop)
# Only need the results for ku and kd
# TODO: Could filter out the time points that aren't on
# the orginal waveform list to save some memory.
ku = cct.voltage_array('ku')[1::] # remove the first point
kd = cct.voltage_array('kd')[1::] # remove the first point
return (ku, kd)
def calcDriverKRamp(model, direction, speed, tstepDivisor=10):
"""
Calculates a Time/Multiplier (TA) Table using 1 Waveform
Arguments:
model -- IBIS Model Class
direction -- either Rising or Falling (constants defined above)
speed -- either Typ, Max, or Min (constants defined above)
tstepDivisor -- Number of simulation points between defined waveform
points, a larger number may yeild a more accurate result but will
take longer to process.
Returns:
(ku, kd) -- two 2D Arrays, the first column in each is time and the
second is either the up (ku) or down (kd) VI Multiplier
Refer to calcDriverKDoubleWave for a general description of the TA Table
creation process. This function uses the ramp data and interpolates
a gaussina rising edge from it to use as a wavefrom example. It is
less accurate as a result but unfortunatally there aren't always 2
waveformes provided in an IBIS Model.
Since there is only a single defined waveform equations (4) and (5) have
to be modified:
Imeas = ku*Ipu - kd*Ipd + Ifix(1)
ku - kd = 1 (2)
Solving (1) for ku:
ku = 1 + kd (3)
Substitute into (2) and solving results in:
Imeas - Ipu - Ifix
kd = ------------------ (4)
Ipu - Ipd
To limit calculation error the paired releationship is used to
calculate ku, not (3):
Imeas - Ipd - Ifx
ku = ------------------ (5)
Ipu - Ipd
"""
warnings.warn(
'IBIS Driver Model based on Ramp Specs only, will have poor accuracy')
#~ vol = model.voltage_range[speed] - model.ramp.dv_r[speed]/0.6
vol = 0.0
#~ voh = model.ramp.dv_r[speed]/0.6
voh = model.voltage_range[speed]
if direction == Rising:
ramp = model.ramp.dt_r[speed]
wave = waveform.Gauss(vol, voh, 0, ramp)
elif direction == Falling:
ramp = model.ramp.dt_f[speed]
wave = waveform.Gauss(voh, vol, 0, ramp)
else:
raise RuntimeError, 'Direction must be Rising or Falling.'
# Based on the schematic defined above
cct = circuit.Circuit("Ramp")
# ----------------------- Waveform -------------------------------------
cct.Vcc = device.V('vcc', 0, model.voltage_range[speed])
cct.Xwv = device.V('wv', 0, 0, wave)
cct.Xpu = device.VI('vcc', 'wv', waveform.PWL(model.pullup[speed]))
cct.Xpd = device.VI('wv', 0, waveform.PWL(model.pulldown[speed]))
cct.Vmeas = device.V('wv', 'ts', 0)
cct.Cc = device.C('ts', 0, model.c_comp[speed])
cct.Rfix = device.R('ts', 'fix', model.ramp.r_load)
if direction == Rising:
cct.Vfix = device.V('fix', 0, 0.0)
elif direction == Falling:
cct.Vfix = device.V('fix', 0, model.voltage_range[speed])
# May not have GND and/or Power Clamps
if hasattr(model, 'power_clamp'):
cct.Xcu = device.VI('vcc', 'ts',
waveform.PWL(model.power_clamp[speed]))
if hasattr(model, 'gnd_clamp'):
cct.Xcd = device.VI('ts', 0, waveform.PWL(model.gnd_clamp[speed]))
# ------------------ Multiplier Calculator -----------------------------
# Equation (4)
cct.Bkdn = device.B('kd', 0, 'v', "(i(Vmeas) - i(Xpu) - i(Vfix))"
"/ (i(Xpd) - i(Xpu))")
# Equation (5)
cct.Bkun = device.B('ku', 0, 'v', "(i(Vmeas) - i(Xpd) - i(Vfix))"
"/ (i(Xpd) - i(Xpu))")
# The simulation length is based on the last time point of the waveform
tstop = ramp * 4
# The simulation step length is based on the step between points 0 and 1.
tstep = ramp * 0.5
# Run the simulations
cct.tran(tstep / tstepDivisor, tstop)
# Only need the results for ku and kd
# TODO: Could filter out the time points that aren't on
# the orginal waveform list to save some memory.
ku = cct.voltage_array('ku')[1::] # remove the first point
kd = cct.voltage_array('kd')[1::] # remove the first point
#~ if direction == Rising and speed == Typical:
#~ import plot
#~ plot.plot(cct)
return (ku, kd)