ECE 201 Lab 2

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Using PSPICE for DC Analysis EEE202 - LAB 2 2.
5 of final grade
Projects and Notes prepared by

Dr. Gabriele Formicone
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OUTLINE

• Introduction to using PSPICE for DC analysis
• 2) Project Assignment

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What is SPICE
SPICE stands for Simulation Program with Integ
rated Circuit Emphasis.
SPICE is a universally available package
for numerical network analysis.
Knowledge of how to use SPICE is required for
ECE 201. SPICE is first discussed in Chapter 4
of Irwin, in the contest of DC network analysis.
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How do I access SPICE for my homework?
Room MAT104 (Computer Lab), has several
high-end PC workstations with PSPICE installed.
You can also get your own FREE evaluation copy,
or student version, from http//www.cadencepc
b.com/products/downloads/PSpicestudent
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For todays Lab
Form groups of 2/3 students each.
Click on START, then pull out Programs.
then pull out PSPICE Student and then click
on the entry schematics.
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Netlists
Irwin discusses the original way we interacted
with SPICE. We did it by storing a netlist in a t
ext file. Netlists are still widely used and ar
e the way one computer ships a network descripti
on to a second. Look under the top tool bar ent
ries of Analysis. Both menus contain options re
lated to netlists.
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Schematic Capture
However, we will use schematic capture.
A schematic capture is the modern way of using a
circuit simulator. The first step in learning ho
w to use SPICE is learning how to draw a circuit
with Schematic Capture. You will use the Edi
t and Draw pull-down menus
to draw a schematic diagram on the monitor.
The internal software will generate the
appropriate netlist which in turn drives the act
ual number crunching. You can examine this ne
tlist if you want, but you dont have to.
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Lets Get Started
Go to the DRAW menu and click on Get new part.
You can also get a part using control-G. Type
R into the dialogue box and hit OK.
Put about a half dozen resistors down by moving
the mouse and clicking on the left mouse button.
When done, click on the right mouse button or
you will keep putting resistors in.
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Lets Get Started
Click on various resistors and move them around.
Click on a resistor and try out the Rotate ent
ry of the Edit pull-down menu. Click on a re
sistor, use the Attribute entry of the
Edit pull-down menu. Change the value
attribute and see what happens. In the attrib
ute area again, use the PKGREF attribute
to rename one of the resistors.
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Lets Get Started
Use the cursor to draw a little box around the
name of a resistor. Then, move the name somepla
ce else. Click on a resistor you do not like.
Then use the delete entry of the Edit pull-d
own menu.
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Play around with the libraries found under
the browser of the get new part command
Check out E, F, G and H under the analog.slb
library. Check out R, L and C also within analo
g.slb library. Check out VAC, VDC, IAC and IDC
of the source.slb library. Check out GND_ANAL
OG and GND_EARTH as well as EGND and AGND of the
port.slb library.
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There are big parts available too!
Examine the RAM8kx1, DAC and ADC parts of the
breakout.slb library. Checkout the mA741 and LM
111 parts under the eval.slb library. These are
op-amps. Semiconductor manufactures also provid
e model libraries for the parts they build. This
makes it possible for some smaller companies to d
esign application circuits without owning a fab
(fab-less semiconductor companies).
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Back to work now! Lets wire few components toget
her.
Clear the screen. You can do this by using the
cursor to enclose all the stuff and then deletin
g. Put a DC voltage source and 2 resistors on
to the screen in spots that roughly correspond to
a voltage divider.
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Wiring components together...
Look for wire on the Draw pull-down menu.
A pencil should appear. As long as the pencil is
there, we are drawing wires. A dotted line wi
ll indicate a wire that is not finished.
A solid line indicates a wire that is finished.
Put the pencil on the positive terminal of the v
oltage source and click the left mouse button.
Move the pencil to a resistor and click the left
mouse button again. Then, click the right mouse
button to stop.
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The mistake that some of you have made
You always should click the right button
once you have wired two components together.
If you didnt do that, you may have actually run
a wire through the middle of one of the compone
nts and have short circuited that component as a
result.
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Creating and examining netlists.
Save your schematic. Call it Lab2ckt and save it
. Then, under the Analysis pull-down menu,
use create Netlist. Then, on the same pull-
down menu, use examine netlist. You should
see lines that describe the type of
part and the nodes that it is connected between.
Compare these node numbers with the voltage di
vider circuit you think you drew.
Copy the netlist down.
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Trying a Simulation
Under the analysis pulldown menu, click on
simulate. Most likely, it wont work. Yo
u probably will find yourself examining the
output. You do this by the examine output c
ommand of the analysis pull-down menu.
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The most common error
At the very end of the output file you probably
are told that every node is floating. SPICE
does nodal analysis! You must specify a grou
nd or reference node. If you do not do that,
every node is floating.
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Putting in a ground
Use the get new part command.
Look under the browser for the AGND
of the port.slb library. Connect the ground t
o one of the nodes. Create a new netlist. Ex
amine it and compare with the original netlist.
What has changed? Try simulate again. Exam
ine the output when done.
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Notice that SPICE tells you the current flowing
through the voltage source.This is important as
we often want to know the current flowing throug
h other types of elements. We can get SPICE t
o tell us this by connecting a
dummy voltage source, with a source voltage of
0V, in series with the element whose current we
wish to measure. By clicking on V and I in th
e schematic tool bar, SPICE will tell us what the
voltages at each node and current through each b
ranches are AFTER we have completed a simulation.
Try it!
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The controlled sources as shown in SPICE
schematics.
Control shown on left. Source type on right.
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Now, connect together a circuit that has a
controlled source, as below (use gain2.5e-3)
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Check it out.
Create the circuit netlist. Examine the netlist
. Simulate the circuit. Examine the output.

Does it make sense?
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Lab Report
Show voltages and currents on the schematic of t
he circuit with the controlled source. Learn ho
w to print results. Analyze the circuit using K
CL and KVL as learned in chapter 2. Does you ana
lysis agree with the voltages and currents the
simulator gives you? Turn printed results in
together with your KCL/KVL analysis.