PSPICE BASICS

General

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Suffixes

f	femto	10-15
p	pico	10-12
n	nano	10-9
u	micro	10-6
m	milli	10-3
k	kilo	103
meg	mega	106
g	giga	109
t	tera	1012

Resistors Capacitors and Inductors:

NAME NODE A NODE B VALUE
with NAME Rxxx = resistor, Lxxx = inductor, Cxxx = capacitor

CS 3 4 1.0uF

.MODEL statement

MODEL NAME	DESCRIPTION
D	Diode
NPN	npn Bipolar Junction Transistor
PNP	pnp Bipolar Junction Transistor
NMOS	n-Channel MOSFET
PMOS	p-Channel MOSFET
NJF	n-Channel JFET
PJF	p-Channel JFET
GASFET	n-Channel GaAs MESFET
RES	resistor
CAP	capacitor
IND	inductor

BJT Parameters

Parameter	Description	Default value
BF	Forward beta	100
CJE	Base-emitterdepletion capacitance	0
CJC	Base-collector depletion capacitance	0
VAR	Reverse Early voltage	infinite
VAF	Forward Early voltage	infinite
BR	Reverse beta	1
NR	Reverse emission coefficient	1
NF	Forward emission coefficient	1

Qxxx collector node base node emitter node Modelname

Q1 3 2 1 NPN
.MODEL NPN NPN(BF=200 CJC=20pf CJE=20pf)

MOSFET Parameters

Parameter	Description	Default value
VTO	Threshold voltage	0
KP	Conductance parameter	0.02 mA/V2
LEVEL	choose zero for ideal
CBD	Drain-to-substrate capacitance	0
CBS	Source-to-substrate capacitance	0
TOX	Oxide-layer thickness	10-7 m

Mname drain gate source bulk/substrate NFET

M1 10 20 0 0 NFET
.MODEL NFET NMOS(LEVEL=0 VTO=2 KP=0.1)

DIODE Parameters

Parameter	Description	Default value
IS	Saturation Current	10-14A
CJO	Junction capacitance at VD = 0	0
VJ	Reverse-breakdown voltage	1V
BV	Reverse-breakdown voltage	infinite
IBV	Current at VD = BV	10-10A
RS	Series Ohmic resistance	0
N	Emission coefficient (ideality factor)	1

Dxxx anode(+) cathode (-) Modelname

D1 2 1 DIODE
.MODEL DIODE D(IS=4.7E-12,N=1)

TYPES OF ANALYSES

.DC (Large-Signal Transfer Characteristic)

Syntax
.DC SOURCE START STOP INCR
SOURCE is the voltage or current source
Transfer characteristics are obtained by incrementing the SOURCE from START to STOP in steps of INCR

Example:
.DC VIN -5 5 0.1

.AC (Sinusoidal Steady-State Frequency Response)

Syntax:
.AC SCALE-TYPE NPOINTS FSTART FSTOP

SCALE-TYPE:

LIN linear increments
NPOINTS specifies the number of frequencies between FSTART and FSTOP

DEC logarithmic increments

NPOINTS defines the number of points per decade

OCT octaves of frequency

NPOINTS defines the number of points per octave

Example:
.AC DEC 50 1K 1MEG
Performs a sinusoidal steady-state analysis over 3 decades of frequency from 1kHz to 1Mhz, computing the response at 50 points within each decade


If an analysis at a single frequency is desired, NPOINTS should be set to one and FSTART = FSTOP


.TRAN (Transient Analysis)

To compute the output of the circuit as a function of time


Syntax:

.TRAN TSTEP TSTOP TSTART TINCR UIC(optional)
Analysis begins at t = 0 and ends at t = TSTOP seconds
output is printed at every increment TSTEP
if TSTART is nonzero it only plots starting at TSTART
if TINCR is omitted the default TINCR value is (TSTOP - TSTART)/50


UIC user initial condition...the initial conditions specified in capacitor and inductor element statements are used instead


NOTE: .IC control line can be used to set an initial condition for any node in the circuit


.TF (Small-Signal Transfer Function)

Syntax:
.TF OUTPUT_VARIABLE INPUT_VARIABLE
To perform a small signal analysis using small-signal linear models for nonlinear devices
INPUT_VARIABLE voltage or current source


Example:
.TF V(1,2) VIN
Finds small-signal voltage gain between nodes 1 and 2 as the output variable


.TF I(V1) VS
Finds the small-signal transconductance using the current through the source V1 as the output variable and VS as the input variable

.TEMP (Temperature Specification)

Syntax
.TEMP VAL1 VAL2 VAL3 ...
Perform the analysis at each temperature VAL in Celsius
Default is 27C (room temperature)


.IC (Initial Conditions)

Syntax:
.IC V(N) = VALUE V(J,K) = VALUE
where N, J, K are node numbers

.STEP (Parameter Step)

Syntax:
.STEP (TYPE) STEPVAR START STOP INCR
Perform simulation while stepping the parameter STEPVAR between the values START and STOP in increments of INCR


NOTE: if .AC or .DC or .TRAN is included Spice will perform these analyses for each value of STEPVAR


TYPE: is optional; LIN (linear increments), DEC (increment points per decade), OCT (incr points per octave), LIST (must be followed by a list of STEPVAR values separated by spaces). Default is LIN