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# -*- coding: utf-8 -*-
"""
Space Baron Team
nats`
Transistor Auto Matcher
Take S parameters file input
"""
import os
import sys
import math
import cmath
def __init__(self, file, freq, config):
self.freq = freq
self.config = config
self.parse_spar(file,freq)
''' Open S2P Files and extract data '''
def parse_spar(self, file, freq):
f = open(file, "r")
tmpspars = []
for line in f:
tmpspars.append(line.strip().split())
self.spars = {}#[] # 1: Freq 2: S11 3: S21 4: S12 5: S22
for l in tmpspars:
if(l[0] != "!" and l[0] != "#"):
tmp = []
tmp.append(complex(float(l[1]), float(l[2]))) # S11
tmp.append(complex(float(l[3]), float(l[4]))) # S21
tmp.append(complex(float(l[5]), float(l[6]))) # S12
tmp.append(complex(float(l[7]), float(l[8]))) # S22
self.spars[float(l[0])] = tmp
''' Calculate John Rollett stability factor '''
def calc_stab(self):
S = self.S
self.K = (1 + cmath.polar(self.Ds)[0] ** 2 - cmath.polar(S[11])[0] ** 2 - \
cmath.polar(S[22])[0] ** 2) / (2 * cmath.polar(S[21])[0] * cmath.polar(S[12])[0])
''' Caculate Maximum Available Gain '''
def calc_mag(self):
S = self.S
self.B1 = 1 + cmath.polar(S[11])[0] ** 2 - cmath.polar(S[22])[0] ** 2 - cmath.polar(self.Ds)[0] ** 2
ksq = 0.0
if self.B1 < 0 :
ksq = math.sqrt(self.K**2 - 1)
else :
ksq = math.sqrt(self.k**2 - 1) * -1
self.MAG = 10 * math.log(cmath.polar(S[11])[0] / cmath.polar(S[12])[0]) + \
10 * math.log(self.K + ksq)
def calc_stability_mag(self):
self.sparam = self.spars[self.freq]
self.S = {}
self.S[11] = self.sparam[0]
self.S[21] = self.sparam[1]
self.S[12] = self.sparam[2]
self.S[22] = self.sparam[3]
S = self.S
self.Ds = S[11] * S[22] - S[12] * S[21]
self.calc_stab()
if self.K < 1 :
print("Warning ! K factor %f < 1.0 , amplifier could be unstable" % self.K)
print("Undefined Maximum Available Gain")
else :
print("Stable amplifier design. K factor %f >= 1" % self.K)
self.calc_mag()
print("Maximum Available Gain: %fdB" % self.MAG)
def calc_scm(self):
S = self S
if self.K > 1 :
self.C1 = S[11] - (self.Ds * complex.conjugate(S[22]))
self.C2 = S[22] - (self.Ds * complex.conjugate(S[11]))
# B1 is already calculated for MAG
self.B2 = 1 - cmath.polar(S[11])[0] ** 2 - cmath.polar(S[22])[0] ** 2 - cmath.polar(self.Ds)[0] ** 2
else :
print("Can't calculate SCM, K < 1, try lossy match")
if __name__ == '__main__':
if(len(sys.argv) < 4):
print("Error: usage\nauto_match.py spar_file.s2p frequency configuration\n")
exit(-1)
fname = sys.argv[1]
freq = float(sys.argv[2])
config = sys.argv[3]
q1 = TransistorBlock(fname, freq, config)
q1.calc_stability_mag()