py2port
Py2port is a tool for performing two-port and one-port analysis on linear circuits. It was developed for analyzing PCB Power-Distribution-Systems and lossy-transmission lines but can be used as a more general purpose simulation tool.
Latest Release
Added phase to the forward and reverse gain plots, cleaned up some of the many, many spelling mistakes, and improved the ferrite example so that it calculates all of the filter characteristics, not just impedance.
Installation
For Linux users download the source code: py2port-1.2. Uncompress it "tar xvjf py2port-x.x.x.tar.bz2" and install "sudo ./setup.py install"
For Windows users download the self-installing executable: py2port-1.2, double-click to install.
Dependencies
Help
Py2port has extensive built-in documentation (docstrings). You can use the pydoc tool or the help command in python to access it.
Examples
The following are a few examples that demonstrate the primary intended usage and capabilities of py2port:
PRBS Script
#!/usr/bin/python
"""
PRBS driving a Lossy T-Line.
"""
import py2port
# Input waveform
vi = py2port.PRBS(bits=50, v1=-1, v2=1, tb='10ns', tr='1ns', tj='100ps')
# Transmission Line (approx 100Ohms) with Source Termination
cct = py2port.Series(py2port.R('100Ohms'))
cct += py2port.W(10, 6.35011e-7, 5.10343e-11, 0.0, 0.0, 0.0, 0.0)
vo = vi >> cct
# Plot the Results
vi.plotVEye('PRBS In')
vo.plotVEye('PRBS Out')
vi.plotI('PRBS In')
# Show the plot
py2port.plot.show()
PRBS Result
Power-Distribution-System Script
#!/usr/bin/python
"""
Impedance of a Power Distribution System from the perspective of a Device.
Includes two types of bypass capacitors, PCB plane impedance, via
inductance, and device pin parasitics, and one device decoupling.
___ ___
.--------o--------o-----|___|----UUU----o----o
| | | Rpin Lpin |
| | | |
--- Zp --- Clf --- Chf ---
--- --- --- ---Cdie
| | | |
| | | ___ ___ |
'--------o--------o-----|___|----UUU----o----o
Rpin Lpin
"""
import py2port
# High Frequency Bypass including mounting inductance
Chf = py2port.Cb(c='100nF', esl='0.5nH', esr='0.039')
Lhf_via = py2port.Lvia('10mil', '62mil', '20mil')
Lhf_mount = py2port.L('1nH') # Esitmate of extra mounnting L
Chf = (Chf*Lhf_via*Lhf_mount) # Put them all in parallel
# Low. Frequency Bypass including mounting inductance
Clf = py2port.Cb(c='12uF', esl='1nH', esr='0.045')
Llf_via = py2port.Lvia('10mil', '62mil', '20mil')
Llf_mount = py2port.L('3nH') # Esitmate of extra mounnting L
Clf = (Clf*Llf_via*Llf_mount) # Put them all in parallel
# PCB Parallel Plane Impedance
Zp = py2port.Cp(x='1in', y='1in', X='20in', Y='10in', h='2mil')
# Put them all in parallel
Zpds = Zp/(Clf//2)/(Chf//10)
# Pin Paracitics
LRpin = py2port.R('0.003') * py2port.L('0.5nH')
Cdie = py2port.C('10pF')
# Put it all together
Zpds = (Zpds * LRpin**2)/Cdie
# Plot the result
Zpds.plotZ(py2port.LogF('10kHz', '1GHz', 100), 'PDS Example')
# Show the plot
py2port.plot.show()
Power-Distribution-System Result
Ferrite Based PI-Filter Script
#!/usr/bin/python
"""
Gain of Ferrite Based Pi-Filter from the perspective of a Device
___
.----------o----------o------|___|---o------------------o
| | | Zbead | |
| ' | | |
--- Plane --- Clf --- Chf*2 --- Clf --- Chf*2
--- --- --- --- ---
| | | | |
| | | | |
'----------o----------o--------------o----------o-------o
"""
import py2port
import numpy
# Ferrite Bead Model
F = numpy.array([0.0001, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 20, 30, 40,
50, 60, 70, 80, 90, 100, 200, 300, 400, 500, 600, 700, 800, 900,
1000, 2000])*1e6
R = [0.35, 0.035, 5, 20, 40, 50, 55, 65, 80, 95, 100, 200, 250, 310,
355, 400, 450, 475, 500, 540, 700, 750, 770, 755, 750, 725, 700,
675, 670, 400]
X = [0, 40, 50, 80, 100, 110, 120, 140, 145, 150, 155, 220, 250, 275,
280, 285, 280, 275, 265, 255, 160, 60, -10, -60, -100, -175, -225,
-250, -275, -285]
Zbead = py2port.Lb(F, R, X)
# High Frequency Bypass including mounting inductance
Chf = py2port.Cb(c='100nF', esl='0.5nH', esr='0.039')
Lhf_via = py2port.Lvia('10mil', '62mil', '20mil')
Lhf_mount = py2port.L('1nH') # Esitmate of extra mounnting L
Chf = (Chf*Lhf_via*Lhf_mount) # Put them all in parallel
# Low. Frequency Bypass including mounting inductance
Clf = py2port.Cb(c='12uF', esl='1nH', esr='0.045')
Llf_via = py2port.Lvia('10mil', '62mil', '20mil')
Llf_mount = py2port.L('3nH') # Esitmate of extra mounnting L
Clf = (Clf*Llf_via*Llf_mount) # Put them all in parallel
# PCB Parallel Plane Impedance
Zp = py2port.Cp(x='1in', y='1in', X='20in', Y='10in', h='2mil')
# Create Two-Port Elements for the structurse on the left
# and right of the Bead.
Aleft = py2port.Shunt(Zp/Clf/(Chf//2))
Aright = py2port.Shunt(Clf/(Chf//2))
# Two-Port Element for the Bead
Abead = py2port.Series(Zbead)
# Connect them all together
Afilter = Aleft + Abead + Aright
# Plot the result
Afilter.plotGf(py2port.LogF('10kHz', '1GHz', 100), 'Pi-Filter Example')
Afilter.plotGr(py2port.LogF('10kHz', '1GHz', 100), 'Pi-Filter Example')
Afilter.plotZin(py2port.LogF('10kHz', '1GHz', 100), 'Pi-Filter Example')
Afilter.plotZout(py2port.LogF('10kHz', '1GHz', 100), 'Pi-Filter Example')
# Show the plots
py2port.plot.show()
Ferrite Based PI-Filter Result
