I. DESCRIPTION AND OBJECTIVES
This laboratory introduces the analog circuit simulation tool, PSpice analyzing a previous
laboratory’s circuit, one you already have direct practical experience with. When you have
finished, you should have acquired basic skills necessary to using it in analysis and synthesis of
analog circuits. We will rely heavily on the lab textbook, “PSPICE for Basic Microelectronics”,
by Joseph G. Tront. This text is particularly useful for learning how to enter circuits using the
Cadence (aka “Orcad”) schematic capture tool: “Capture”. This popular EDA tool is also used as
the front-end for PCB layout design, and is covered in ECE174. Here we will use it specifically
II. GENERAL DISCUSSION
Learning to use modern simulation programs (or “tools”) today is an essential part of design and
experimental verification of electronic circuits.
The first such program, SPICE2, was developed in the 1970’s as a funded research project at UC
Berkeley. The acronym stands for: Simulation Program with Integrated Circuit Emphasis. The
original public domain Fortran4 code (yes, complete with card-readers, et. al.) formed the trunk
of a tree of several later successful variations, the most popular being PSPICE, the “P” standing
for personal computer. It was developed by MicroSim for use on the original IPM-PC in 1984.
Microsim added a GUI wrapper around the original computation engine that read and parsed the
circuit netlist from a text file and proceeded to simulate it. It also included another wrapper
around the results, again a much needed GUI, called Probe that provided a means to flexibly
analyze results graphically. MicroSim being very successful was acquired by Orcad in 1998, and
immediately integrated PSpice into their schematic capture engine, Capture. The ability to draw
an engineering schematic, rather than tediously describe it as a formatted netlist in a text file was
a major improvement. (the first was the text file that replaced Fortran’s punched cards). Cadence
later acquired Orcad in 2005 and has continued to improve the program and GUI. It now has a
spectrum of variations available to developers.
A relatively recent addition to the Spice family of programs, is LTSpice, written by Linear
Technologies to specifically optimize the ability to simulate non-linear switch-mode power
circuits that feature, as you might expect, their IC’s. LTSpice is free and can be used for general
A/D (analog/digital) circuit analysis. It is very popular with students, and is generally easier to
undertand and use initially than the Cadence variations. You are free to use it, but for the
purposes of this lab, we will be reviewing and using one of the Cadence PSpice Capture tools.
If you don’t already have them, they can be installed from two possbile sources:
1. Obtain the program from Bels and install it on your computer. BSOE has a site license
from Cadence, but it can be used with or without the license. A VPN tunnel will be
needed to access our license server here at UCSC (see Bels for instructions on doing this)
to use the full version. Without a license Capture / Pspice will run in “Lite” mode that is
more than adequate for this lab.
2. Go to Cadence’s website and request to install the Orcad Free Trial Version.The Cadence
link is on our website. This is full-featured but will default to the older “Lite version”
after the trial period ends. As already noted above, this is more than adequate for this lab.
A discussion of the Capture program and how to use it with PSpice will be presented as a hands-
on discussion over Zoom. Also, several pdf file references for both PSpice and LTSpice are
noted on our website.
1. Develop a PSPICE model to simulate your small-signal diode experiment. Use this to verify
the DC Q-Point and corresponding AC response for at least two of your measured data
2. Perform a frequency sweep that results in a Bode Plot of the high-pass response in log/log
form. This will require the use of formulas in Probe, a plotting tool that is part of PSPICE.