def test_filtered_noise3(self):
"""Lcapy: check circuit filtered noise"""
a = Circuit()
a.add('V1 1 0 noise 20')
a.add('R1 1 2 1')
a.add('C1 2 0 2')
self.assertEqual(a.C1.V.n.rms(), 5 * sqrt(2),
"Incorrect capacitor voltage")
def test_filtered_noise3(self):
"""Lcapy: check circuit filtered noise"""
a = Circuit()
a.add('V1 1 0 noise 20')
a.add('R1 1 2 1')
a.add('C1 2 0 2')
self.assertEqual(a.C1.V.n.rms(), 5 * sqrt(2),
"Incorrect capacitor voltage")
def value_rms(self):
return self.value_peak() / sqrt(2)
from lcapy import f, sqrt
In = 1e-12 * sqrt(250 / f + 1)
ax = (In * 1e12).plot((0.1, 10e3), loglog=True)
ax.grid(True, 'both')
ax.set_ylabel('Noise current density pA$/\sqrt{\mathrm{Hz}}$')
ax.set_ylim(0.1, 100)
from matplotlib.pyplot import savefig
savefig(__file__.replace('.py', '.png'), bbox_inches='tight')
from lcapy import f, sqrt
Vn = 1e-9 * sqrt(3.5 / f + 1)
ax = (Vn * 1e9).plot((0.1, 10e3), loglog=True)
ax.grid(True, 'both')
ax.set_ylabel('Noise voltage density nV$/\sqrt{\mathrm{Hz}}$')
ax.set_ylim(0.1, 10)
from matplotlib.pyplot import savefig
savefig(__file__.replace('.py', '.png'), bbox_inches='tight')
from lcapy import s, sympify, j, sqrt
zeta = sympify('zeta_', real=True)
omega0 = sympify('omega0', real=True)
p1a = -zeta * omega0 + j * omega0 * sqrt(1 - zeta**2)
p1b = -zeta * omega0 - j * omega0 * sqrt(1 - zeta**2)
alpha1 = sympify('alpha_1', real=True)
omega1 = sympify('omega_1', real=True)
p1a = -alpha1 + j * omega1
p1b = -alpha1 - j * omega1
H = p1a * p1b / ((s - p1a) * (s - p1b))
G = H / s
g = G.partfrac().inverse_laplace(causal=True)
h = H.partfrac().inverse_laplace(causal=True)
def topy(expr):
s = str(expr)
s = s.replace('**', '^').replace('_', '').replace('*', ' * ').replace(
'^', '**').replace('Heaviside(t)', '(t >= 0)').replace('/', ' / ')
return s
print(topy(g))
from lcapy import Circuit, sqrt, f, oo
Rs = 30
G = 1000
R1 = 100
R2 = (G - 1) * R1
Vn = 1e-9 * sqrt(3.5 / f + 1)
In = 1e-12 * sqrt(250 / f + 1)
T = 273 + 20
k_B = 1.38e-23
a = Circuit('opamp-noninverting-amplifier.sch')
an = a.noisy()
Vno = an[8].V.n(f)
Vno = Vno.limit('A', oo)
Vnov = Vno.subs({
'R1': R1,
'R2': R2,
'In1': 0,
'In2': 0,
'Vn': Vn,
'Rs': Rs,
'k_B': k_B,
'T': 0