PSpice User Guide

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PSpice A/D User Guide October 2019 615 Product Version 17.4-2019 © 2022 All Rights Reserved. 14 Digital simulation Chapter overview This chapter describes how to set up a digital simulation analysis and includes the following sections: ■ What is digital simulation? on page 616 ■ Steps for simulating digital circuits on page 616 ■ Concepts you need to understand on page 617 ■ Defining a digital stimulus on page 619 ■ Defining simulation time on page 633 ■ Adjusting simulation parameters on page 634 ■ Starting the simulation on page 636 ■ Analyzing results on page 637

Articles in this issue

Cover
Contents
Before you begin
Welcome
Comparison of PSpice A/D Tiers
How to use this guide
Symbols and conventions
Related documentation
PSpice A/D Samples and Tutorials
Part one: Simulation primer
Things you need to know
Chapter overview
What is PSpice A/D?
Analyses you can run with PSpice A/D
Basic analyses
Advanced multi-run analyses
Analyzing waveforms with PSpice A/D
What is waveform analysis?
Using PSpice A/D with other programs
Using design entry tools to prepare for simulation
What is the PSpice Stimulus Editor?
What is the PSpice Model Editor?
Files needed for simulation
Files that design entry tool generates
Other files that you can configure for simulation
Files that PSpice A/D generates
Directory structure for analog projects in Capture
How are files configured at the design level maintained in the directory structure for analog projects?
How are files configured at the profile level maintained in the new directory structure for analog projects?
What happens when I convert an analog project that uses a design from another project or from another location?
What should I do if the schematic for a converted analog project uses FILESTIMn parts from the SOURCE library?
Design Entry HDL libraries
Reference Libraries
Local libraries
PSpice model libraries
The cds.lib file
Encrypting PSpice Models
Using PSpiceEnc
Using Model Editor
Simulation examples
Chapter overview
Example circuit creation
Using Capture
Using Design Entry HDL
Using Design Templates
Finding out more about setting up your design
Running PSpice A/D
Performing a bias point analysis
Using the simulation output file
Finding out more about bias point calculations
DC sweep analysis
Setting up and running a DC sweep analysis
Displaying DC analysis results
Finding out more about DC sweep analysis
Transient analysis
Finding out more about transient analysis
AC sweep analysis
Setting up and running an AC sweep analysis
AC sweep analysis results
Finding out more about AC sweep and noise analysis
Parametric analysis
Setting up and running the parametric analysis
Analyzing waveform families
Finding out more about parametric analysis
Performance analysis
Finding out more about performance analysis
Part two: Design entry
Preparing a design for simulation
Chapter overview
Checklist for simulation setup
Typical simulation setup steps
Advanced design entry and simulation setup steps
When netlisting fails or the simulation does not start
Using parts that you can simulate
Vendor-supplied parts
Passive parts
Breakout parts
Behavioral parts
Simulating asymmetric parts in PSpice A/D
Simulating homogeneous parts in PSpice A/D
Specifying values for part properties
Using Global Parameters and Expressions for Values
Global parameters
Expressions
Defining power supplies
For the analog portion of your circuit
For A/D interfaces in mixed-signal circuits
Defining stimuli
Analog stimuli
Digital stimuli
Things to watch for
Unmodeled parts
Unconfigured model, stimulus, or include files
Unmodeled pins
Missing ground
Missing DC path to ground
Creating and editing models
Chapter overview
What are models?
How are models organized?
Model libraries
Model library configuration
Global vs. design vs. profile models and libraries
Nested model libraries
PSpice-provided models
Model library data
Device characteristic curves-based models vs. Template-based models
Tools to create and edit models
Ways to create and edit models
Using the Model Editor
Ways to use the Model Editor
Running the Model Editor alone
Starting the Model Editor
Creating models using the Model Editor
Creating models based on device characteristic curves
Creating models based on PSpice templates
Importing an existing model
Enabling and disabling automatic part creation
Running the Model Editor from the schematic editor
Model creation examples
Example: Creating a PSpice model based on device characteristic curves
Example: Creating template-based PSpice model
Editing model text
Example: editing a Q2N2222 instance model
Using the Create Subcircuit Format Netlist command (Capture only)
Changing the model reference to an existing model definition
Reusing instance models
Reusing instance models in the same schematic
Making instance models available to all designs
Configuring model libraries
The Configuration Files tab
How PSpice A/D uses model libraries
Adding model libraries to the configuration
Changing the model library scope from profile to design, profile to global, design to global and vice versa
Changing model library search order
Order of Access and Precedence for Models used in Simulation
Changing the library search path
Handling smoke information using the Model Editor
Adding smoke information to PSpice models
Creating template-based PSpice models with smoke information
Using the Model Editor to edit smoke information
Examples: Smoke
Adding smoke information to the D1 diode model
Adding smoke information to the OPA_LOCAL operational amplifier model
Smoke parameters
Diode
Bipolar Junction Transistors
Magnetic Core
Ins Gate Bipolar Transistor (IGBT)
Junction FET
Operational Amplifier
MOSFET
Voltage Regulator
Darlington Transistor
Creating parts for models
Chapter overview
What's different about parts used for simulation?
Ways to create parts for models
Preparing your models for part creation
Starting the Model Editor
Using the Model Editor to create parts
Batch mode of part creation
Interactive mode of part creation
Creating Design Entry Tool parts for all models in a library
Using batch mode
Using interactive mode
Setting up automatic part creation
Example
Creating parts in the batch mode
Creating parts using interactive mode
Basing new parts on a custom set of parts
Editing part graphics (Capture only)
How Capture places parts
Defining grid spacing
Attaching models to parts
MODEL
Defining part properties needed for simulation
PSPICETEMPLATE
IO_LEVEL
MNTYMXDLY
PSPICEDEFAULTNET
Analog behavioral modeling
Chapter overview
Overview of analog behavioral modeling
The ABM part library file
Placing and specifying ABM parts
Net names and device names in ABM expressions
Forcing the use of a global definition
ABM part templates
Control system parts
Basic components
Limiters
Chebyshev filters
Integrator and differentiator
Table look-up parts
Laplace transform part
Math functions
ABM expression parts
An instantaneous device example: modeling a triode
PSpice-equivalent parts
Implementation of PSpice-equivalent parts
Modeling mathematical or instantaneous relationships
Lookup tables (ETABLE and GTABLE)
Frequency-domain device models
Laplace transforms (LAPLACE)
Frequency response tables (EFREQ and GFREQ)
Cautions and recommendations for simulation and analysis
Instantaneous device modeling
Frequency-domain parts
Laplace transforms
Trading off computer resources for accuracy
Basic controlled sources
Creating custom ABM parts
Digital device modeling
Chapter overview
Introduction
Functional behavior
Timing characteristics
Timing model
Propagation delay calculation
Inertial and transport delay
Input/Output characteristics
Input/Output model
Defining Output Strengths
Charge storage nets
Creating your own interface subcircuits for additional technologies
Creating a digital model using the PINDLY and LOGICEXP primitives
Digital primitives
Logic expression (LOGICEXP primitive)
Pin-to-pin delay (PINDLY primitive)
BOOLEAN
PINDLY
Constraint checker (CONSTRAINT primitive)
Setup_Hold
Width
Freq
74160 example
Part three: Setting up and running analyses
Setting up analyses and starting simulation
Chapter overview
Analysis types
Setting up analyses
Order for standard analyses
Output variables
Setting AutoConvergence
Using Advanced Analog Options
Performance package
Starting a simulation
Creating a simulation netlist
Starting a simulation from a Design Entry Tool
Starting a simulation outside of Design Entry Tool
Setting up batch simulations
The PSpice A/D simulation window
Interacting with a simulation
Extending a transient analysis
Interrupting a simulation
Scheduling changes to runtime parameters
Setting Autoconvergence from the Runtime Settings Dialog Box
Using the Simulation Manager
Overview of the Simulation Manager
Setting up multiple simulations
Starting, stopping, and pausing simulations
Attaching PSpice A/D to a Simulation
Setting options in the Simulation Manager
DC analyses
Chapter overview
DC Sweep
Minimum requirements to run a DC sweep analysis
Overview of DC sweep
Setting up a DC stimulus
Nested DC sweeps
Curve families for DC sweeps
Bias point
Minimum requirements to run a bias point analysis
Overview of bias point
Small-signal DC transfer
Minimum requirements to run a small-signal DC transfer analysis
Overview of small-signal DC transfer
DC sensitivity
Minimum requirements to run a DC sensitivity analysis
Overview of DC sensitivity
AC analyses
Chapter overview
AC sweep analysis
Setting up and running an AC sweep
What is AC sweep?
Setting up an AC stimulus
Setting up an AC analysis
AC sweep setup in example.opj
How PSpice A/D treats nonlinear devices
Noise analysis
Setting up and running a noise analysis
What is noise analysis?
Setting up a noise analysis
Analyzing Noise in the Probe window
Parametric and temperature analysis
Chapter overview
Parametric analysis
Minimum requirements to run a parametric analysis
Overview of parametric analysis
RLC filter example
Example: frequency response vs. arbitrary parameter
Temperature analysis
Minimum requirements to run a temperature analysis
Overview of temperature analysis
Transient analysis
Chapter overview
Overview of transient analysis
Minimum requirements to run a transient analysis
Defining a time-based stimulus
Overview of stimulus generation
Using CheckPoints
Specifying CheckPoints
Restarting Simulation from a Saved CheckPoint
The Stimulus Editor utility
Stimulus files
Configuring stimulus files
Starting the Stimulus Editor
Defining stimuli
Creating new stimulus symbols
Editing a stimulus
Deleting and removing traces
Manual stimulus configuration
Finding out more about the Stimulus Editor
Transient (time) response
Internal time steps in transient analyses
Switching circuits in transient analyses
Plotting hysteresis curves
Fourier components
Monte Carlo and sensitivity (worst-case) analyses
Chapter overview
Statistical analyses
Overview of statistical analyses
Output control for statistical analyses
Model parameter values reports
Monte Carlo history support
Waveform reports
Collating functions
Temperature considerations in statistical analyses
Monte Carlo analysis
Example: Monte Carlo analysis of a pressure sensor
Monte Carlo Histograms
Worst-case analysis
Overview of worst-case analysis
Worst-case analysis example
Tips and other useful information
Digital simulation
Chapter overview
What is digital simulation?
Steps for simulating digital circuits
Concepts you need to understand
States
Strengths
Defining a digital stimulus
Using the DIGSTIMn part
Defining input signals using the Stimulus Editor
Using the DIGCLOCK part
Using STIM1, STIM4, STIM8 and STIM16 parts
Using the FILESTIMn parts
Defining simulation time
Adjusting simulation parameters
Selecting propagation delays
Initializing flip-flops
Starting the simulation
Analyzing results
Adding digital signals to a plot
Adding buses to a waveform plot
Tracking timing violations and hazards
Mixed analog/digital simulation
Chapter overview
Interconnecting analog and digital parts
Interface subcircuit selection by PSpice A/D
Level 1 interface
Level 2 interface
Setting the default A/D interface
Specifying digital power supplies
Default power supply selection by PSpice A/D
Creating custom digital power supplies
Interface generation and node names
Digital worst-case timing analysis
Digital worst-case timing
Digital worst-case analysis compared to analog worst-case analysis
Starting digital worst-case timing analysis
Simulator representation of timing ambiguity
Propagation of timing ambiguity
Identification of timing hazards
Convergence hazard
Critical hazard
Cumulative ambiguity hazard
Reconvergence hazard
Glitch suppression due to inertial delay
Methodology
Part four: Viewing results
Analyzing waveforms
Chapter overview
Overview of waveform analysis
Elements of a plot
Elements of a Probe window
Managing multiple Probe windows
Setting up waveform analysis
Setting up colors
Viewing waveforms
Setting up waveform display from design entry tools
Viewing waveforms while simulating
Using schematic page markers to add traces
Using display control
Using plot window templates
Limiting waveform data file size
Viewing large data files
Using simulation data from multiple files
Comparing measured data with simulated data
Saving simulation results in ASCII format
Analog example
Mixed analog/digital tutorial
About digital states
About the oscillator circuit
Setting up the design
Running the simulation
Analyzing simulation results
User interface features for waveform analysis
Zoom regions
Scrolling traces
Showing and hiding traces
Sizing digital plots
Modifying trace expressions and labels
Moving and copying trace names and expressions
Copying and moving labels
Tabulating trace data values
Using cursors
Tracking digital simulation messages
Message tracking from the message summary
Message tracking from the waveform
Trace expressions
Basic output variable form
Output variable form for device terminals
Analog trace expressions
Digital trace expressions
Measurement expressions
Chapter overview
Measurements overview
Measurement strategy
Procedure for creating measurement expressions
Setup
Composing a measurement expression
Viewing the results of measurement evaluations
Example
Viewing the results of measurement evaluations.
Measurement definitions included in PSpice A/D
For power users
Creating custom measurement definitions
Definition example
Measurement definition syntax
Syntax example
Other Output Options
Chapter overview
Viewing analog results in the PSpice A/D window
Writing additional results to the PSpice output file
Generating plots of voltage and current values
Generating tables of voltage and current values
Generating tables of digital state changes
Creating test vector files
Exporting Trace to CSV File
Bias Point Display
Introduction
How bias information is stored and updated
Bias point data for multiple analyses
Displaying bias point values
Controlling the display of bias points
Moving bias points
Updating bias point values
Menu commands for bias point display
Toolbar controls for bias point display
Toggling a specific current bias display
Toggling a specific voltage bias display
Toggling a specific power bias display
Setting initial state
Appendix overview
Save and load bias point
Save bias point
Load bias point
Setpoints
Setting initial conditions
Convergence and "time step too small errors"
Appendix overview
Introduction
Newton-Raphson requirements
Is there a solution?
Are the equations continuous?
Is the initial approximation close enough?
Diagnostics
Bias Point (DC) Convergence
DC Sweep Convergence
Transient Convergence
Importing Spice Models
Appendix Overview
Introduction
Importing text models
Generating Part Symbols
Creating New Symbols
Using symbols from an existing symbol library
Using Model Import wizard
Configuring new model library
Editing Model Editor created symbols
Index

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