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Computer Aided Design

Course 2

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Spice Simulation

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.OPJ Capture project file

.DSN Capture design file

.OLB Capture part library file

.UPD Property update file

.DRC Design rules check file

.BOM Bill of Materials file

.EXP Export properties file

Common File Extensions

.MNL Layout netlist file

.SWP Layout backannotation file

.XRF Cross-reference report

.NET or .ASC Other netlist files

.VHD or .VHO VHDL source file

.EDF EDIF 2.0 netlist

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Project Manager Window

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Schematics Editing steps Start a new project, select “Analog or

Mixed A/D” (enables PSpice) Create a new directory to hold the files

and provide a descriptive file name Create the project Add the PSpice library (ex. “analog.olb”) Build and wire the circuit Annotate Run Design Rules Check (DRC) Build Bill of Materials (BOM) Print

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Automatic Reference Designator Assignment

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Design Rules Check

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Create BOM to List Footprints

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PSpice Analysis Flow

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New Simulation Profile

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Simulation Settings Menu

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Bias Point Display

Enable bias voltage display

Enable bias currents display

Enable power display

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BASIC PART ABBREVIATIONS

Resistor R

capacitor C

current-controlled current source F

current-controlled voltage source H

ground, analog AGND

voltage-controlled current source G

voltage-controlled voltage source E

Simple voltage source VAC

Transient sine voltage source VSIN

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Analog stimuliThe analog stimuli symbols available in Schematics are:

If you want this kind of input... Use this symbol for voltage... For DC analyses DC bias VDC or VSRC For AC analyses AC magnitude and phase VAC or VSRCFor transient analyses exponential VEXP or VSTIM* periodic pulse VPULSE or VSTIM* piecewise-linear VPWL or VSTIM*

piecewise-linear that repeats forever VPWL_RE_FOREVER or VPWL_F_RE_FOREVER**

piecewise-linear that repeats n times VPWL_N_TIMES or VPWL_F_N_TIMES**frequency-modulated sine wave VSFFM or VSTIM*sine wave VSIN or VSTIM*

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*. VSTIM and ISTIM symbols require the Stimulus Editor to define the input signal.

**. FILE-BASED Symbols: VPWL_F_RE_FOREVER and VPWL_F_N_TIMES are file-based symbols; the stimulus specification resides in a file and adheres to PSpice netlist syntax. To determine the symbol name for an equivalent Current source-In the table of voltage source symbols, replace the first V in the symbol name with I (Example: VDC -> IDC).

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Stimulus Symbols for Analog Time-Based Input Signals

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To use any of these source types, you must place the symbol in your schematic and then define its transient behavior. Each attribute-characterized stimulus has a distinct set of attributes depending upon the kind of transient behavior it  represents.

For VPWL_F_xxx and IPWL_F_xxx, a separate file contains the stimulus specification. Defining VSTIM or ISTIM using the Stimulus Editor

Defining Stimulus Symbol Attributes Manually in Schematics

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As an alternative, the Stimulus Editor utility automates the process of defining the transient behavior of stimulus devices.

The Stimulus Editor allows you to create analog stimuli which generate sine wave, repeating pulse, exponential pulse, single-frequency FM, and piecewise linear waveforms. It also facilitates creating digital stimuli with complex timing relations.

This applies to both stimulus symbols placed in your schematic as well as new ones that you might create.

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Stimulus Editor

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HOW DOES SPICE WORK? Basically, SPICE operates like this: 1. Describe a circuit in a text file (“.cir” extension) called a netlist OR draw the circuit using graphical symbols on a schematic page. 2. Run a simulation. SPICE reads the netlist and then performs the requested analysis: AC, DC, or TRANSIENT RESPONSE. The results are stored in a text output file (“.out” extension) or a binary data file.3. View the results of the simulation in a text output file ( “.out” ) using a text editor. Most SPICE programs provide a graphical viewer to plot the waveforms stored in the binary data file (Probe window).

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Netlist File* source CIRC1V_V1 N00129 0 +SIN 0 1 1k 0 0 0R_R1 N00129 N00138 1k L_L1 N00138 N00145 10uH C_C1 0 N00145 1n

V1

FREQ = 1kVAMPL = 1VOFF = 0

R1

1k

1 2L1

10uH

C11n

0

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NETLIST OR SCHEMATIC PAGE? Although, the schematic capture has its advantages, each SPICE vendor has a different drawing interface and file format. This would cause great confusion if you used a version of SPICE different from the one used at this site. Also, the learning curve for the schematic capture can be steep. Many component characteristics are not visible from the schematic. (Ultimately, the schematic capture program creates a netlist before running a simulation.)

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NETLIST OR SCHEMATIC PAGE? The netlist description of a circuit is simple and fairly consistent for each SPICE vendor with some variations. The entire circuit and component properties are visible. Learning the netlist is easy and making changes is fast. You can create a netlist by drawing the circuit on paper and applying a few simple rules.

(Several books written on SPICE strongly recommend learning the netlist, even if you decide later to use a schematic capture program.)

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NETLIST

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NETLIST

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Output File**** 03/05/06 16:06:27 ******* PSpice 10.3.0 (Jan 2004) ******* ID# 1111111111 ** Profile: "SCHEMATIC1-circ1" [ C:\ORCAD_DATA\CAD\circ1-PSpiceFiles\SCHEMATIC1\circ1.sim ]

**** CIRCUIT DESCRIPTION******************************************************************************** Creating circuit file "circ1.cir" ** WARNING: THIS AUTOMATICALLY GENERATED FILE MAY BE OVERWRITTEN BY SUBSEQUENT SIMULATIONS*Libraries: * Profile Libraries :* Local Libraries :* From [PSPICE NETLIST] section of C:\OrCAD\OrCAD_10.3\tools\PSpice\PSpice.ini file:.lib "nom.lib"

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Output File - 2*Analysis directives: .TRAN 0 10ms 0 .PROBE V(alias(*)) I(alias(*)) W(alias(*)) D(alias(*)) NOISE(alias(*)) .INC "..\SCHEMATIC1.net"

**** INCLUDING SCHEMATIC1.net ***** source CIRC1V_V1 N00129 0 +SIN 0 1 1k 0 0 0R_R1 N00129 N00138 1k L_L1 N00138 N00145 10uH C_C1 0 N00145 1n

**** RESUMING circ1.cir ****.END

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Output File - 3**** 03/05/06 16:06:27 ******* PSpice 10.3.0 (Jan 2004) ******* ID# 1111111111 ** Profile: "SCHEMATIC1-circ1" [ C:\ORCAD_DATA\CAD\circ1-PSpiceFiles\SCHEMATIC1\circ1.sim ] **** INITIAL TRANSIENT SOLUTION TEMPERATURE = 27.000 DEG C****************************************************************************** NODE VOLTAGE NODE VOLTAGE NODE VOLTAGE NODE VOLTAGE(N00129) 0.0000 (N00138) 0.0000 (N00145) 0.0000

VOLTAGE SOURCE CURRENTS NAME CURRENT

V_V1 0.000E+00

TOTAL POWER DISSIPATION 0.00E+00 WATTS

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Output File - 4JOB CONCLUDED

**** 03/05/06 16:06:27 ******* PSpice 10.3.0 (Jan 2004) ******* ID# 1111111111 ** Profile: "SCHEMATIC1-circ1" [ C:\ORCAD_DATA\CAD\circ1-PSpiceFiles\SCHEMATIC1\circ1.sim ]

**** JOB STATISTICS SUMMARY

******************************************************************************

Total job time (using Solver 1) = .19

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Probe window

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Probe window

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Probe window

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Probe window