pspice

PSPICE is general-purpose circuit program that can be applied to

simulate and calculate the performance of electrical and electronic circuits. A

circuit is described to a computer by using a file called the circuit file, which

is normally typed in from a keyboard. The circuit file contains the circuit

details of components and elements, the information about the sources, and

the command for what to calculate and what to provide as output. The circuit

file is the input file to the PSPICE program, which, after executing the

commands, produces results in another file called the output file.

1. Format of circuit files: -

i) Title

ii) Circuit description

iii) Analysis description

iv) Output description

v) END (end of file statement)

Note: 1) The first line is the title line, and it may contain any type of text.

2) The last line must be the End command.

3) Continuation of line is identified by a plus sign (+) in the first

column of the next line.

4) A comment line may be included anywhere, preceded by on

asterisk (*).

2. Format of output files: -

The results of simulation by PSPICE are stored in on output file. The

output file may be divided into following types:

i) A description of the circuit itself that includes the net list, the device

list, the model parameter list, and so on.

ii) Direct output from some of the analysis without .PLOT and

.PRINT Commands. This includes the output from. .OP, .TF,

.SENS, NOISE and. FOUR Analyses.

iii) Prints and plots by . PRINT and . PLOT commands, These

include the output from the .DC, .AC, and .TRAN analysis.

iv) Run statements. These include the various kinds of summary

information about the whole run, including times required by

various kinds of analysis and the amount of memory used.

v) In electrical circuits, subscriptions are normally assigned to symbols

for voltages, currents and circuit elements. However, in PSPICE, the

symbols are represented without subscripts. For example, VS, IS, and

RI are represented by VS, IS and RI, respectively.

3. Element values: - There are two types of suffixes: The scale suffix and units suffix.

Scale Suffix:

Scale suffix Value

F 1E-15 P 1E-12 N 1E-9 U 1E-6

MIL 25.4E-6 M 1E-3 K 1E3

MEG 1E9 G 1E9 T 1E12

Note: ‘M’ means “milli” not “mega”

Unit Suffix:

Unit Suffix Its Unit OHM Ohm (Ω)

V Volt H Henry A Amp F Farad HZ Hertz

DEG Degree

Note: The first suffix is always the scale suffix, and the unit suffix

follows the scale suffix.

3. Nodes: -

The location of an element is identified by the node numbers. Each

element is connected between two nodes. Node numbers must be integers

from 0 to 9999 for Spice 2, but need not be sequential. PSPICE allows any

alphanumeric string up to 131 characters long. The node names shown in

table are reserved and cannot be used.

Reserved node names Value Description 0 0volts Analog Ground $ D-HI 1 Digital High level $ D-LO 0 Digital low level

$ D-X X Digital unknown level

4. Circuit Elements:-

Circuit Elements are identified by names. A name must start with a

letter symbol corresponding to the element, but after that it can contain either

letters or numbers. Names can be up to 8 characters long for SPICE 2, and up

to 131 characters long for PSPICE. However, names longer than 8 characters

are not normally necessary and not recommended.

Table shows the first letters of elements and sources.

Table: A: Symbols of circuit elements and sources.

First Letter Circuit elements and Sources

B Ga As MES field – effect transistor

C Capacitor

D Diode

E Voltage controlled voltage source

F Current controlled current source

G Voltage controlled voltage source

H Current controlled voltage source

I Independent source.

J Junction field transformer

K Mutual Inductors (transformer)

L Inductor

M Mos. Field effect transistor.

Q Bipolar junction transistor.

R Resistor

S Voltage controlled switch

T Transmission line

V Independent voltage source

W Current controlled switch.

Passive Elements: -

5.1.1. DC Circuit Analysis: -

Resistor:-

The symbol for a resistor is ’R’.

The name of resistor must start with ‘R’.

The General form of Resistor is:

R<name> N+ N- R NAME R VALUE.

Example: -

a) R5 1 2 5

b) RL 5 2 1K

5.1.2. Transient Analysis: -

5.1.2(a) Inductor:-

The symbol for an inductor is ‘L’

The name of inductor must start with L.

The General form of inductor is:

L<name> N+ N- L NAME L VALUE IC = IO Example: -

a) LI 1 3 5MH

b) L LOAD 5 6 10H

5.1.2 (b) Capacitor:-

The symbol for capacitor is ‘c’.

The name of capacitor must start with ‘c’.

The General form of capacitor is:

C<name> N+ N- C NAME C VALUE IC = VO.

Example: -

a) C2 1 0 9UF

b) C LOAD 5 2 10F

5.2 Sources:- The General format for source is

< Source name > < positive node > < negative node > < source model >

5.2(i) DC Circuit Analysis: -

5.2.1: Independent DC Sources:-

The Independent DC sources can be time invariant or time variant.

They can be currents or voltages.

5.2.1.1.(a). Independent DC Voltage Source:-

Voltage source Current source

The symbol for an independent voltage source is ‘V’

The General form is:

V < name > N+ N- [DC < value >]

Example: -

V5 5 1 DC 5V

VS 1 2 5V

5.2.1.1(b) Independent DC Current Source:- The symbol of an independent current sources in ‘I’.

The General form is:

I < name > N+ N- [DC(value)]

Example:-

I3 1 0 DC 1A ;

I4 1 5 1A

5.2.1.2. Dependent Sources: -

The four types of dependent sources are:

Voltage controlled voltage source

Current controlled current source

Current controlled voltage source.

Voltage controlled cu rent sou

r rce

Voltage controlled voltage source. Voltage controlled current source

Current controlled current source. Current controlled voltage source.

These sources can have either a fixed value or a polynomial expression.

POLY (n) < (controlling nodes)> <(coefficients) Values >

The general form polynomial source is:

Polynomial source:

Let →call A, B, and C be the three controlling variables, and y be the output

nomial source output takes the form of Y = F( A, B, C, …….).

….+ Pn An.

- Po P1 P2 P3 …….Pn.

tively of

f degree n=2 with A and B controlling.

6A3 + P7 A2B + P8AB2 + P9B3

d in Pspice as

+ NC2– Po P1 P2…….Pn.

source.

The poly

→For a polynomial of n=1 with A as the only controlling variable,

The source function takes the form of

Y = Po + P1A + P2A2 + P3A3 + P4A4 +

Where Po, P1, P2,…. Pn are the coefficient values.

This is written in Pspice as

POLY NCI+ NCI

Where NCI+ and NCI- are the positive and negative nodes respec

controlling source A.

→ For a polynomial o

Sources the source function takes the form of

Y = Po + P1A + P2B + P3A2 + P4AB + P5B2 + P

+ P10A4 + …..

This is describe

POLY(2) NC+ NC- NC2

Example:-

(a). For Y = 2 V(10), The model is

3[V(5)]3 + 4[V(5)]4 The model is

V(3)V(5). The model is

POLY 10 0 2.0

(b).For Y= V(5) + 2[V(5)]2 +

POLY 5 0 0.0 2.0 3.0 4.0.

(c). For Y = 0.5 + V (3) + 2 V (5) + 3[V (3)]2 + 4

POLY (2) 3 0 5 0 0.5 1.0 2.0 3.0 4.0,

5.2.1.2.(b): Voltage controlled voltage sources:-

The symbol of a voltage controlled voltage source is ‘E’.

The General form is:

E< name > N+ N– NC+ NC- <(voltage gain) value>

The non-linear form is:

E< name > N+ N– [POLY (< value >)

+ < <(+ Controlling) node> (-controlling) node > > (pairs)

+ [< (Polynomial coefficients) values >]

Example:-

a) EAB 1 2 4 6 1.0

b) E NON LIN 25 40 POLY (2) 3 0 5 0 0.0 1.0 1.5 1.2

X = V (3) + 1.5 V (5) +1.2 [V (3)]2

5.2.1.2 (c): Voltage Controlled Current Source:-

The symbol of a voltage controlled current source is ‘G’.

The General form is:

G< name > N+ N- NC+ NC- <(trans conductance) value >.

The non-linear form is:

G < name > N+ N- [poly < (value) >

+ < < (+ Controlling) node> < ( - controlling ) node > > (pairs)

+ < (Polynomial coefficients) values >].

Example: -

a) GAB 2 4 6 1.0

b) G NON LIN 25 40 POLY(2) 3 0 5 0 0.0 1.0 1.5 1.2 1.7

5.2.1.2 (d): Current controlled Current Source: -

The symbol of the current controlled current source is ‘F’.

The General form is:

F< name > N+ N- VN< (Current gain) value >.

The non-linear form is:

F< name > N+ N- [POLY (< value > >

+ VNI, VN2, VN3, ……..

+ < (Polynomial coefficients) values>]

Example:-

a) FAB 1 2 VIN 10

b) F NON LIN 25 40 POLY VN 0.0 1.0 1.5 1.2 1.7

I =1.0 [V(N)] + 1.5 [I (VN)]2 + 1.2 [I(VN)]3 + 1.7 [I(VN)]4

5.2.1.2 (e): Current – controlled Voltage Source:-

The symbol of a current controlled source is ’H’.

The General form is:

H< name > N+ N- VN < (Trans resistance) value>

The non linear form is:

H< name > N+ N- [POLY (< value >)

+ VNI, VN2, VN3,…………………..

+ < (Polynomial coefficients) values >]

Example:-

a) HAB 1 2 VIN 10

b) H NON LIN 25 40 POLY VN 0.0 1.0 1.5 1.2 1.7.

V = I [VN] + 1.5 [I (VN)]2 + 1.2 [I(VN)]3 + 1.7 [I(VN)]4

5.2.2: Transient analysis:- 5.2.2.1: Modeling of Transient Source:-

5.2.2.1.(a) Pulse Source: -

V

V2

V1

0 t

TD TR PW TF

PER

The waveform and parameters of a pulse waveform are shown in figure and

table.

The symbol of pulse source is “pulse”.

The General form is:

PULSE (V1 V2 TD TR TF PW PER)

Name Meaning Units Default

V1 Initial voltage Volts None

V2 Pushed voltage Volts None

TD Delay time Seconds 0

TR Rise time Seconds TSTEP

TF Fall time Seconds TSTEP

PW Pulse Seconds TSTOP

PER Period Seconds TSTOP

Example: PULSE (-1 1 2NS 2NS 2NS 50NS 100NS)

5.2.2.1 (b) : Piece wise Linear Source: -

The General form is:

PWL ( T1 V1 T2 V2 T3 V3…..TN VN)

Table: Model parameter of PWL sources.

Name Meaning Units Default

Ti Time at a point Seconds None

Vi Voltage at a point Volts Name

Example: -

V

10V

0 10ms t

The model statement for above ware form is:

PWL (0 0 10MS 10V 20MS 0)

5.2.2.1 (C): Sinusoidal Source:-

The symbol of sinusoidal source is SIN,

The General form is:

SIN (VO VA FREQ TD ALP THETA)

The model parameters of SIN waveform are given in

Name Meaning Units Default

VO Offset Voltage Volts None

VA Peak voltage Volts None

FREQ Frequency Hertz 1/Tstop

TD Delay time Seconds 0

ALPHA Damping factor 1/Seconds 0

THETA Phase delay Degrees 0

5.2.2.2: Transient Sources: -

Voltage source Current source

5.2.2.2 (a): Independent voltage sources:-

The symbol of independent voltage source is V.

The general form for assigning DC and transient values is:

V< name > N+ N- [DC < value >]

+ [(Transient value)

+ [PULSE] [SIN] [PWL] [source arguments]]

5.2.2.2 (b): Independent current source: -

The symbol of independent current source is ‘I’.

The General form for assigning DC and transient values is:

I< name > N+ N- [DC < value >]

+ [PULSE] [SIN] [PWL] [source arguments]].

5.2.3: AC Analysis: - Independent AC sources: -

The statements for a voltage and current source have the following

general forms:

V< name > N+ N- [AC < (magnitude) value > (phase) value >]

I< name > N+ N- [AC < (magnitude) value > <phase) value >]

The < (magnitude) value > is the peak value of sinusoidal voltage. The <

(phase) value > is in degrees.

6. OUTPUT VARIABLES: -

A DC dummy voltage source of 0V (say Vx = 0V) is normally added

and used as an ammeter to measure the current of that source eq. I(Vx)

6.1. DC Circuit analysis: -

D.C output variables; -

6.1.1: Voltage output: -

For DC sweep and transient analysis, the output voltages can be

obtained by the following statements.

V (< name >): Voltage at node N1 with respect to node N2

V (< name >): Voltage across two Terminal device, < name >

Vx (< name >): Voltage at terminal x of three- terminal device, < name >

Vxy(< name >): Voltage across terminals x and y of three terminal device,

< name >

Vz (< name >): Voltage at point ‘Z ‘ of transmission line, < name >

6.1.2: Current output:-

For DC sweep and transient analysis, the output currents can be

obtained by the following statements:

I( < name > ) current through < name >

Ix( < name > ) current into terminal x of < name >

Iz (< name >) current at port x of transmission line, < name >

6.2: Transient Analysis:-

The output variables of transient analysis are similar those of D.C.

circuit analysis.

6.3: AC Analysis: - AC output variables: -

SUFFIX MEANING

(None)

M

DB

P

G

R

I

Peak Magnitude

Peak Magnitude

Peak Magnitude in decibel

Phase in radians

Group delay (S phase / S flow)

Real Part

Imaginary Part

6.3.1: Voltage output: -

The statements for AC analysis are similar to those for the DC sweep

and the transient analysis. Provided the suffixes are added as follows:

Variables Meaning

VM(5)

VM

VP (D1)

VR (2,3)

VI (2,3)

Magnitude of voltage at node 5 w. r.t. Ground.

Magnitude of voltage at node 4 w. r.t node 2.

Phase of anode voltage of diode (D1) w. r.t. Cathode

Real part of voltage at node 2 w.r.t. Node 3

Imaginary part of voltage at node 2 w.r.t. node 3.

6.2.2: Current output: -

Variables Meaning

IM (R5)

IR (R5)

II (R5)

IM (VIN)

Magnitude of current through resistor R5

Real part of current through resistor R5

Imaginary part of current through resistor R5.

Magnitude of current through source in.

7. PSPICE output commands: - The most common forms of output are print tables and plots, and they

require output commands. However, with .OP command, PSPICE

automatically direct all node voltages and the current and power dissipation

of all voltage sources to the output file, and therefore does not require any

output command.

7.1: DC Circuit analysis: -

7.1.1: Types of output: -

The commands that are available to get output from the result of simulations

are:

1) . PRINT Print

2) . PLOT Plot

3) . PROBE Probe output.

7.1.1.1: .PRINT (Print statements): -

The print statement for DC outputs takes the form:

. PRINT DC [output variables].

7.1.1.2: .PLOT (plot statement): -

The plot statement for the DC outputs takes the following form:

. PLOT DC < output variables >

+ [< (Lower limit) Value > < (Upper limit) value >]

7.1.1.3: .PROBE ( Probe statement): -

The command makes one of these forms:

. PROBE

. PROBE < one or more output variables >.

7.2: Transient analysis:-

Transient output commands: -

The .PRINT, .PLOT and .PROBE statements for transient output are:

. PRINT TRAN < output variables >

. PLOT TRAN < output variables >

+ [< (Lower limit) value >, < (upper limit) value >]

.PROBE

8. Types of Analysis: - D.C. circuit analysis, Transient analysis and A.C. analysis.

8.1.: DC Circuit Analysis: - The commands that are commonly used for DC analysis are:

1) .OP DC operating point

2) .TF small signal transfer function

3) .DC DC sweep.

The statement for performing the DC sweep is:

.DC LIN SWNAME SSTART SEND SINC

+ [(nested sweep specification)].

Another form of DC sweep is:

.DC SWNAME LIST < value >

+ [(nested sweep specification)]

8.2: Transient Analysis: -

A Transient response determines the output in the time domain in

response to an input signal in time domain. The determination of the transient

analysis required statements involving.

1) .IC - Initial transient conditions.

2) .TRAN - Transient analysis.

8.2.1: .IC(Initial Transient Conditions):

The various nodes can be assigned to initial voltages during transient

analysis, and the general form for assigning initial value is

.IC V(1) = A1 V(2) = A2 ………….V(N) = AN

8.2.2: .TRAN (Transient Analysis): -

Transient analysis can be performed by the .TRAN command, which has one

of the general forms.

.TRAN T STEP T STOP [T START T MAX] [UIC]

.TRAN [/op] TSTEP TSTOP [TSTART TMAX] [UIC]

5US 1MS 200US 0.1NS UIC

8.3: AC ANALYSIS: -

The command for performing frequency response takes one of the following

general forms.

. AC LIN NP F START F STOP.

9: Modeling of circuit elements : - The general from of model statement is

. MODEL MNAME TYPE (P1 =A1 P2 A2…..PN =AN)

Type Name Element

RES Resistor

CAP Capacitor

D Diode

IND Inductor

NPN NPN bipolar junction Transistor

PNP PNP bipolar junction Transistor

V SWITCH Voltage –Controlled Switch

I SWITCH Current controlled switch

10. Advanced Spice Commands: -

10.1: SUBCKT (Subcircuit): -

Pspice allows one to define a small circuit as a sub circuit, which then

can be called upon in several places in the main circuit.

The General form for sub circuit definition is:

.SUBCIRCUIT SUBNAME [< (two or more) nodes >]

The symbol for a sub circuit call is X.

The general form of a call statement is:

X <Name> [< (two or more) nodes >] SUBNAME

10.2: .ENDS (End of sub circuit): -

A sub circuit must end with .ENDS statement.

The end of a sub circuit definition has the general form

.ENDS SUBNAME.

10.3: .Options: -

Pspice allows various options to control and to limit parameters for the

various analyses.

The general form is

.OPTIONS [< (options) name >] [< (options) name > = < value >]

10.4: .PARAM ( Parameter): -

The parameter definition is one of the following form:

.PARAM < P NAME = < VALUE > or < expression >.

10.5: .STEP (parametric analysis) : -

The .STEP command can be used to evaluate the effects of parameter

variations.

The general forms are:

.STEP LIN SWNAME SSTART SEND SINC

. STEP SWNAME LIST< value >.

10.6: .DC (DC Parametric sweep) : -

The general statements are:

.DC LIN SWNAME SSTART SEND SINC

.DC SWNAME LIST<value>

11 .SWITCHES: -

a) Switch b) On state c) Off – State

(1)Voltage – Controlled Switch

(2) Current – Controlled Switch.

11.1: Voltage Controlled Switch: -

Voltage – controlled switch

The symbol for voltage controlled switch is S.

The name of this switch must start S, and it takes the general form of

S< name > N+ N- NC+ NC- S NAME

Name Meaning Units Default

VON Control Voltage for On Start Volts 1.0

VOFF Control Voltage for off start Volts 0

RON On Resistance 0hms 1.0 ROFF Off Resistance 0hms 106

11.2: Current Controlled Switch: -

The symbol for current controlled switch is W.

The name of the switch must start with W. and the general form is

W< Name > N+ N- VN W NAME.

Current – Controlled Switch.

Name Meaning Units Default

I ON Control current for on state Amps 1E – 3

I OFF Control current for off state Amps 0

R ON On resistance Ohms 1.0

R OFF Off resistance Ohms 106

12. DIODES: -

The symbol for a diode is D.

The name of a Diode must start with D, and it takes the general form

D< name > NA NK DNAME [(area) Value ]

.MODEL DNAME D

(P1 =A1 P2 = A2 P3 = A3……..PN = AN)

13.Transister: -

The symbol for BJT is Q.

The name of BJT must start with Q, and it takes the general form:

Q< name > NC NB NE NS QNAME

14.PSPICE THYRISTOR MODEL:

Let us assume that the Thyristor as shown in fig (1) is operated from

an AC supply. This Thyristor obeys the following characteristics.

1. The thyristor switch to the ON state with the application of a

small positive gate voltage, provided that the anode-to-cathode

voltage is positive.

2. It should remain in the ON – state as long as the anode current

flows.

3. It should switch to the off – state when the anode current goes

through zero toward the negative direction.

The switching action of the thyristor can be modeled by a voltage –

controlled switch and a polynomial source and is shown in fig (2).

The turn – ON process can be explained by the following steps:

1. For a positive gate voltage Vg between nodes 3 and 2, the gate

current is

Ig = I(VX) = G

g

RV

2. The gate current Ig activates the current controlled current source

F1 and produces a current of value Fg = P1 Ig = P1 . I (VX) such

that F1 = Fg + Fa.

3. The current source Fg produces a rapidly rising voltage VR across

resistance RT.

4. As the voltage VR increases above zero. The resistance RS of the

voltage controlled switch S1 decreases from ROFF toward RON.

5. As the resistance RS of switch S1 decreases, the anode current Ia

= I(VY) increases, provided that the anode – to – cathode voltage

is positive. This increasing anode current Ia produces a current Fa

= P2 Ia = P2 . I(VY). This results in an increased value of voltage

VR.

6. This produces a regenerative condition with the switch rapidly

being driven into low resistance (ON State). The switch remains

on if the gate voltage Vg is removed.

7. The anode current Ia continues to glow as long as it is positive and

the switch remains in the on – state.

During te turn – off, the gate current is off and Ig = 0.

That is, Fg = 0, F1 = Fg + Fa = Fa.

The turn – off operation can be explained by the following steps:

1. As the anode current Ia goes negative, the current F1 reverses

provided that the gate voltage Vg is no longer present.

2. With a negative F1, the capacitor discharges through current

source F1 and the resistance RT.

3. With the fall of voltage VR to a low level, the resistance RS of

switch S1 increases from low (RON) to high (ROFF).

4. This is again a regenerative condition with the switch resistance

being driven rapidly to ROFF value as the voltage VR becomes

zero.

This model works well with a converter circuit in which the thyristor

current falls of the current. But for a full wave AC – DC converter with

a continuous load current, the current of a thyristor is diverted to

another thyristor and this model may not give the true output. This

problem can be remedied by adding diode DT as shown in fig (2). The

diode prevents any reverse current flow through the thyristor resulting

form the firing of another thyristor in the circuit.

This thyristor model can be used a sub circuit. switch ‘S1’ is

controlled by the controlling between nodes 6 and 2. the switch and /

or anode parameters can be adjusted to yield the desired on – state

drop of the thyrisor – we shall use diode parameters IS = 2.2 E – 15,

BV = 1800V, TT = 0, and switch parameters RON = 0.125, ROFF = 10E

+ 5, VON = 0.5V, VOFF = 0V.

The sub circuit definition for the thyristor model SCR can be described

as follows: ∗ Subcircuit for AC thyristor model.

∗ SCR 1 2 3 2

∗ Model Anode Cathode + Control - Ve control Name voltage voltage

• SUBCKT SUBNAME [ < (two or more) nodes > ]

S1 1 5 6 2 SMOD; Voltage controlled switch

S < name> N + N - NC + NC- SNAME RG 3 4 50

VX 4 2 DC 0V

VY 5 7 DC 0V

DT 7 2 DMOD ; Switch diode

D <name> NA NK DNAME RT 6 2 1

CT 6 2 10UF

F1 2 6 POLY (2) VX VY 0 50 11

F <name> N+ N- [Poly (< value >) VNI VN2 …. < (Polynomial

coefficient value> ]

• MODEL S MOD VSWITCH (RON = 0.0125 ROFF = 10E + 5

VON = 0.5V VOFF = 0.V) ; Switch model

• MODEL MNAME TYPE (P1 = A1 P2 = A2 ----- PN = AN)

• MODEL DMOD D (IS = 2.2 E – 15 BV = 1800V TT = 0)

• MODEL DNAME D(P1 = A1 P2 = A2 ---- PN = AN) ; Diode

Model parameters

• ENDS SCR ; Ends sub circuit definition.

• ENDS SUBNAME

IS = Saturation current

BV = Reverse break down voltage

TT = Transient time