The George Washington University School of Engineering and Applied Science Department of Electrical and Computer Engineering

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The George Washington UniversitySchool of
Engineering and Applied ScienceDepartment of
Electrical and Computer Engineering

• Circuit Design Verification
• Using PSpice (Cadence/OrCAD)

Jason Woytowich (former GTA) Farid Hassani (ECE
GTA)
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Outline

• Introduction
• General Process
• Basic Example Half-Wave Rectifier
• Advanced Example Demodulation

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Introduction

• SPICE is a general purpose circuit simulation
  language that performs non-linear DC, transient
  and linear steady state AC analysis.
• SPICE models
• Linear circuit elements of resistance,
  capacitance, inductance, independent and
  dependent current and voltage sources
• Four of the most common nonlinear semiconductor
  devices (Diodes, BJTs, JFETs and MOSFETs)
• Other useful circuit elements including
  transmission lines and mutual inductance

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Cadence PSpice

• OrCAD bought MicroSim and its PSpice products in
  January 1998.
• Cadence bought OrCAD in August 1999.

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General Process

• 1. Design your circuit
• 2. Draw your circuit
• 3. Specify your analysis
• 4. Run the simulation
• 5. Analyze the output
• 6. Go back to 1, 2 or 3 as needed

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Starting Cadence
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Starting Cadence
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Start a New Project
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Select Project Options
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Project Types

• Only two types are of immediate concern
• Analog or Mixed A/D
• The project is meant for simulation. This is for
  design verification.
• Schematic
• This option is used for PCB design. It is only
  used to generate a netlist. We will use this for
  your Board Fabrication Details.

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Create a Blank Project
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Schematic
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Place Parts
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Placing Parts
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Changing Values
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Completed Half-Wave Rectifier
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Create a Simulation Profile
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Set the Simulation Parameters
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Simulation Types

• DC / OpPoint All AC sources are zeroed
  (Shorted/Opened)
• Transient View with respect to time
• DC Sweep View the response to a range of DC
  inputs
• AC Sweep View the response to a range of
  frequencies

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Run the Simulation

• Press the blue arrow in the toolbar on the top.

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Select Output
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Output 1
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More Output
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Output 2
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A More Complicated Example

• Input 5Vpeak, 2kHz Sine Wave pulsed for 5ms
  ever 20ms starting 1ms and an output impedence of
  1kOhm
• The input passes through a simple BPF with a gain
  of 1.
• The output of the BPF is rectified and passed
  through an RC filter with a time constant of
  0.5ms.
• Put the output across a 1Meg Ohm resistor.

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Using Heirarchy

• You can break your Pspice design into modules.
• These modules can be linked together at the top
  level.

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Signal Source
MULT From ABM
VDC
VSIN
VPULSE
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Band Pass Filter
LM741 from OPAMP
Input Port
Output Port
Notice the power supply connections
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Rectifier
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Top Level
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Simulation

• Is the output what you expect?

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Simulation
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Perform Your Own Simulations

• This presentation was adapted from a presentation
  by Farid Hassani