def distributed_rlgc_from_sdb(length_m,
freq,
Sdb,
Sdeg,
z0_probe=complex(50, 0)):
# length_m: (m) Length of structure being measured
# s2p_filename: (str) s2p filename
# z0_probe: (Ohms) Impedance of network analyzer/probes. 50 Ohm default.
Sri = rfs.sdb2sri(Sdb, Sdeg)
abcd = rfs.s2abcd(Sri, z0_probe, z0_probe)
d_vec = np.zeros((len(abcd)), dtype=complex)
c_vec = np.zeros((len(abcd)), dtype=complex)
for idx, T in enumerate(abcd):
d_vec[idx] = T[1][1]
c_vec[idx] = T[1][
0] # C vector (what I think needs to be used for Zc extraction)
gamma = 1 / length_m * np.arccosh(d_vec)
Zc = 1 / c_vec * np.sinh(gamma * length_m)
R = (gamma * Zc).real
L = 1 / 2 / math.pi / freq * ((gamma * Zc).imag)
G = (gamma / Zc).real
C = 1 / 2 / math.pi / freq * (gamma / Zc).imag
losstan = (gamma / Zc).real / (gamma / Zc).imag
attenuation = 20 * np.log10(abs(np.exp(-gamma * length_m)))
return (freq, R, L, G, C, gamma, attenuation, losstan, Zc)
def get_pad_abcd(pad_L_s2p_filename,
pad_2L_s2p_filename,
z0_probe=complex(50, 0)):
(freq_L, Sdb_L, Sdeg_L) = rfs.get_sdb_from_vna_csv(pad_L_s2p_filename)
(freq_2L, Sdb_2L, Sdeg_2L) = rfs.get_sdb_from_vna_csv(pad_2L_s2p_filename)
# ABCD matrices
S_L = rfs.sdb2sri(Sdb_L, Sdeg_L)
S_2L = rfs.sdb2sri(Sdb_2L, Sdeg_2L)
abcd_L = rfs.s2abcd(S_L, z0_probe)
abcd_2L = rfs.s2abcd(S_2L, z0_probe)
abcd_pad = np.zeros(np.shape(abcd_L),
dtype=complex) # ABCD matrix structure for pad
abcd_pad_inv = np.zeros(
np.shape(abcd_L),
dtype=complex) # inverse abcd matrix structure for pad
# iterating across each frequency point
for idx, abcd_L_mat in enumerate(abcd_L):
abcd_2L_mat = abcd_2L[idx]
abcd_L_inv = la.inv(abcd_L_mat)
abcd_P_squared = la.inv(
np.dot(abcd_L_inv,
np.dot(abcd_2L_mat,
abcd_L_inv))) # PP = ( ML^-1 * M2L * ML^-1 )^-1
abcd_P = la.sqrtm(
abcd_P_squared
) # ABCD matrix of the pad (single pad) for this frequency
abcd_P_inv = la.inv(abcd_P)
abcd_pad[idx] = abcd_P
abcd_pad_inv[idx] = abcd_P_inv
Sri_pad = rfs.abcd2s(abcd_pad, z0_probe, z0_probe)
(Sdb_pad, Sdeg_pad) = rfs.sri2sdb(Sri_pad)
return (freq_L, abcd_pad, abcd_pad_inv, Sri_pad, Sdb_pad, Sdeg_pad)