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)))
