def solve_abcd(self, freqs, refnode = gnd, complexfreq = False):
(inp, inn), (outp, outn) = self.ports
toolkit = self.toolkit
## Add voltage source at input port and create
## copies with output open and shorted respectively
circuit_vs_open = copy(self.cir)
circuit_vs_open['VS_TwoPort'] = VS(inp, inn, vac=1)
circuit_vs_shorted = copy(circuit_vs_open)
circuit_vs_shorted['VL_TwoPort'] = VS(outp, outn, vac=0)
## Run AC-analysis on the two circuits
ac_open = AC(circuit_vs_open, toolkit=toolkit)
ac_shorted = AC(circuit_vs_shorted, toolkit=toolkit)
res_open = ac_open.solve(freqs, refnode = refnode,
complexfreq=complexfreq)
res_shorted = ac_shorted.solve(freqs, refnode = refnode,
complexfreq=complexfreq)
A = res_open.v(inp, inn) / res_open.v(outp, outn)
B = res_shorted.v(inp, inn) / res_shorted.i('VL_TwoPort.plus')
C = res_open.i('VS_TwoPort.minus') / res_open.v(outp, outn)
D = res_shorted.i('VS_TwoPort.minus') / res_shorted.i('VL_TwoPort.plus')
return np.array([[A,B],[C,D]], dtype=object)
def test_loopanalysis_numeric():
cir = SubCircuit()
cir['A1'] = VCVS(gnd, 'int', 'out', gnd, g = 10)
cir['R1'] = R('in', 'int')
cir['probe'] = LoopProbe('out', gnd, 'out_R2', gnd)
cir['C2'] = C('int', 'out_R2')
cir['VS'] = VS('in', gnd)
ana = FeedbackLoopAnalysis(cir)
res = ana.solve(np.logspace(4,6), complexfreq=True)
print abs(res['loopgain'])
def test_loopanalysis_viiv():
sympy.var('R1 R2 CL A s')
cir = SubCircuit(toolkit=symbolic)
cir['A1'] = VCVS(gnd, 'int', 'out', gnd, g = A, toolkit=symbolic)
cir['R1'] = R('in', 'int', r=R1)
cir['probe'] = LoopProbe('out', gnd, 'out_R2', gnd, toolkit=symbolic)
cir['R2'] = R('int', 'out_R2', r=R2)
cir['VS'] = VS('in', gnd)
ana = FeedbackLoopAnalysis(cir, toolkit=symbolic)
res = ana.solve(s, complexfreq=True)
assert sympy.simplify(res['loopgain'] - (- A * R1 / (R1 + R2))) == 0
def test_deviceanalysis_viiv():
"""Loopgain of a resistor V-I and a I-V amplifier with a vcvs as gain element"""
sympy.var('R1 R2 CL A s')
cir = SubCircuit(toolkit=symbolic)
cir['A1'] = VCVS(gnd, 'int', 'out', gnd, g = A,toolkit=symbolic)
cir['R1'] = R('in', 'int', r=R1)
cir['R2'] = R('int', 'out', r=R2)
cir['VS'] = VS('in', gnd)
ana = FeedbackDeviceAnalysis(cir, 'A1', toolkit=symbolic)
res = ana.solve(s, complexfreq=True)
assert simplify(res['loopgain'] - (- A * R1 / (R1 + R2))) == 0
def test_deviceanalysis_sourcefollower():
"""Loopgain of a source follower"""
gm,RL,CL,s = sympy.symbols('gm RL CL s')
cir = SubCircuit(toolkit=symbolic)
cir['M1'] = VCCS('g', 's', gnd, 's', gm = gm,toolkit=symbolic)
cir['RL'] = R('s', gnd, r=RL)
cir['CL'] = C('s', gnd, c=CL)
cir['VS'] = VS('g', gnd)
ana = FeedbackDeviceAnalysis(cir, 'M1', toolkit=symbolic)
res = ana.solve(s, complexfreq=True)
assert_equal(simplify(res['loopgain']), simplify(- gm / (1/RL + s*CL)))
def solve(self, freqs, complexfreq = False, refnode = gnd):
toolkit = self.toolkit
result = InternalResultDict()
if self.method == 'sparam':
result['twoport'] = self.solve_s(freqs, complexfreq=complexfreq)
abcd = result['twoport'].A
else:
abcd = self.solve_abcd(freqs, refnode=refnode, complexfreq=complexfreq)
result['twoport'] = NPortA(abcd)
result['mu'] = 1 / abcd[0,0]
result['gamma'] = 1 / abcd[0,1]
result['zeta'] = 1 / abcd[1,0]
result['beta'] = 1 / abcd[1,1]
if self.noise:
(inp, inn), (outp, outn) = self.ports
circuit_vs = copy(self.cir)
circuit_vs['VS_TwoPort'] = VS(inp, inn, vac = 1)
circuit_cs = copy(self.cir)
circuit_cs['IS_TwoPort'] = IS(inp, inn, iac = 1)
if self.noise_outquantity == 'i':
for src in circuit_vs, circuit_cs:
src['VL'] = VS(outp, outn, vac = 0)
if self.noise_outquantity == 'v':
na = Noise(circuit_vs,
inputsrc='VS_TwoPort',
outputnodes=(outp, outn),
toolkit=toolkit,
epar=self.epar)
res_v = na.solve(freqs, complexfreq=complexfreq,
refnode=refnode)
na = Noise(circuit_cs,
inputsrc='IS_TwoPort',
outputnodes=(outp, outn),
toolkit=toolkit,
epar=self.epar)
res_i = na.solve(freqs, complexfreq=complexfreq,
refnode=refnode)
else:
na = Noise(circuit_vs,
inputsrc='VS_TwoPort',
outputsrc='VL',
toolkit=toolkit,
epar=self.epar)
res_v = na.solve(freqs, complexfreq=complexfreq,
refnode=refnode)
na = Noise(circuit_cs,
inputsrc='IS_TwoPort',
outputsrc='VL',
toolkit=toolkit,
epar=self.epar)
res_i = na.solve(freqs, complexfreq=complexfreq,
refnode=refnode)
result['Svn'] = res_v['Svninp']
result['Sin'] = res_i['Sininp']
self.result = result
return result