pspice final
DESCRIPTION
psice software details-developed by electrical and electronics department of university of berkeleyTRANSCRIPT
PSPICE
Introduction
• What’s Spice?– SPICE Simulation Program with Integrated Circuit Emphasis
– SPICE contains models for common circuit elements, active as well as passive.
• Why Spice?
– SPICE can provide information about circuit performance that is almost impossible to obtain with laboratory prototype measurements.
ORCAD PSPICE
Using PSPICE the user can do three types of processesCaptureLayoutPSPICE A/D
Types of files in PSPICE A/D
File Type Description
.cir The basic input file for PSPICE
.out The output file generated. Contains Output data and errors
.dat If too much data is produced (e.g. transient analysis) then this can be made as the output file and handled by the “probe”
.inc include files, to store frequently used subcircuits not added to the library
.lib library files
Specifying a Circuit File
It has three main parts1. Element Statements : Describe the elements in the circuit
2. Control Statements : Describe the types of analyses to be performed
3. Output Statements : Specifies the output to be printed or plotted
The circuit is described as elements connected between nodes.
General Structure of a Circuit File
;Title Statement
Signal Source(s)
Element Statements
Control Statements
Output Statements
.end
Circuit File
Comments must begin with * or ; First line is always a comment . The statements can be arranged in any order. The last line is always .end To continue a statement on a new line use
the ‘+’ sign
Each node must be uniquely labeled.
Elements
PSPICE allows modeling of circuits with both active and passive elements like o Resistor o Inductor o Capacitor o Diodeo Transistor
PSPICE Elements
Prefix for unitsCode Metric
PrefixDecimal
Representation
T Tera 1012
G Giga 109
Meg Mega 106
K Kilo 103
M milli 10-3
U micro 10-6
N nano 10-9
P pico 1012
F femto 10-15
Data Statements - Sources
Independent DC Sources
Voltage Source : Vname n+ n- Type ValueCurrent Source : Iname n+ n- Type Value
Type: AC or DC E.g. Vin 1 0 dc 12 Is 3 4 dc 1.5
Example
V1 1 0 DC 10VV2 4 0 DC 34V
Passive Elements
SPICE considers the current always flows from the positive node through the element to the negative node.
ELEMENT PSPICE DESCRIPTION
Rname n+ n- value
Lname n+ n value
Cname n+ n- value
Example
Dependent Sources - VCVS
Voltage Controlled Voltage source Statement:Ename n+ n- nc+ nc- α
Example *Name n+ n- nc+ nc- gainEbar 17 8 42 18 24.0;
First letter always ‘E’
Voltage Controlled Current Source Statement:Gname n+ n- nc+ nc- γ
Example: *Name n+ n- NC+ NC γGlab 23 17 8 3 2.5
First letter always ‘G’
Dependent Sources - VCCS
Current Controlled Current Source Statement:Fname n- n+ VMonitor β Vmonitor n1 n2 DC 0V
First letter always ‘F’n1
n2
Dependent Sources - CCCS
Example:*Name n- n+ Vmonitor GainFtrn 81 19 Vctl 50.0Vclt 23 12 DC 0V ;controls Ftrn
n1
n2
Dependent Sources - CCCS
Current Controlled Voltage Source Statement:Hname n+ n- VMonitor gain Vmonitor n1 n2 DC 0V
First letter always ‘H’
Dependent Sources - CCVS
Note
PSPICE does not support open circuits . Every node must be uniquely labeled and
must have at least two connections . Node 0 is always reserved for ground . In case analysis must be done on an open
circuit, a very high resistance value must be used in place of an infinite resistance.
PSPICE is not case sensitive.
Basic Analysis Types
DC Analysis .DC .OP
Transient Analysis .TRAN
AC Analysis .AC
Standard Analyses Commands .OP .DC .AC .TRAN .FOUR .NOISE .SENS
DC Analysis
.OP Statement
Causes detailed information about the bias point to be printed Voltage at the nodes Current in each voltage source Total power dissipation Operating point for each element
If not specified, it automatically performs a DC analysis before doing a transient or ac analysis
Example
V1 1 0 DC 10VV2 4 0 DC 34VR1 1 2 6ohmR2 2 3 4ohmR3 3 4 2ohm.OP.ENDex 1.1.cir
DC Analysis
.DC Statement Performs a linear, logarithmic, or nested DC
sweep analysis Calculates the circuit’s bias point over a
range of values for <sweep variable name>
.DC Statement – Linear Sweep
General Form.DC [LIN] <sweep variable name>+<start value> <end value> <increment value>
+[nested sweep specification]
.DC Statement - LIST
General Form
.DC <sweep variable name> [LIST] <value>*
+[nested sweep specification] Example
.DC V1 LIST 2 4 8 9 13
Output Control Commands
.PRINT .PLOT .PROBE .WATCH .VECTOR (for digital simulation)
Allows results from DC, AC, noise, and transient analyses to be an output to the output file. (print tables)
General Form.PRINT <analysis type> <output variable>* Example
.PRINT DC V(1,2) I(R4)
ExampleV1 1 0 DC 10VV2 4 0 DC 34VR1 1 2 6ohmR2 2 3 4ohmR3 3 4 2ohm.DC V1 LIST -34V +0V 34V.PRINT DC V(1,4) +I(R1).OP.END
ex 1.2.cir
.PLOT
Causes results from DC, AC, noise, and transient analyses to be line printer plots in the output file.
General Form.PLOT <analysis type> [output variable]*
+ ([<lower limit value>,<upper limit value>])*
Example:
.PLOT TRAN V(2)
Example
V1 1 0 DC 10VV2 4 0 DC 34VR1 1 2 6ohmR2 2 3 4ohmR3 3 4 2ohm.DC LIN V1 0V 34V 1V.PLOT DC V(1,4).OP.ENDex 1.3.cir
.PROBE
Writes the results from DC, AC, and transient analyses to a data file used by Probe
General Form
.PROBE [output variable]* Example
.PROBE V(2)I(R5)
Example
V1 1 0 DC 10VV2 4 0 DC 34VR1 1 2 6ohmR2 2 3 4ohmR3 3 4 2ohm.DC LIN V1 0V 34V 1V.PROBE.OP.END
ex 1.4.cir
Circuit File Processing Commands .END
Marks the end of the circuit.
Can there be more than one .END commands
in a .cir file?
Find the currents in each branch using PSPICE
01
2 3
i2
i6
i4i3
i1>
>
|v |
i5 >
_
_
_>
-
R66 ohm
R53 ohmR4
3 ohm
R31 ohm
R22 ohm
R12 ohm
Is112A
Is1 1 2 12AR1 2 3 2R2 2 3 2R3 1 0 1R4 1 0 3R5 3 0 3R6 0 3 6.DC Is1 LIST 12A.PRINT DC I(R1) +I(R2) I(R3)I(R4) +I(R5) I(R6).OP.END
kcl.cir
Find the voltages at nodes 1,2 ,3
0
2 31
R48 ohm1/4 v2
R31 ohm
R26 ohm
R12 ohm
+
-
Vs13V
Vs1 1 0 3VR1 1 2 2ohmR2 2 0 6ohmR3 2 3 1ohmG1 3 0 2 0 0.25R4 3 0 8ohm.DC Vs1 LIST 3V.PRINT DC V(1) +V(2) V(3).OP.END
nodal.cir
Find Thevenin Equivalent of the circuit to the left of points a and b
0
1 2 3
Is215A
R36 ohm
R23 ohm
R12 ohm
Is115A
+
-
Vs220V
R51 ohm
Is215A
R36 ohm
R23 ohm
R12 ohm
Is115A
+
-
Vs220V
R51 ohm a
b
Determination of Open Circuit Voltage
321
0
Is215A
Is115A
+
-
Vs220V
R36 ohm
R12 ohm
R51 ohm
Vs2 1 0 20VR5 1 2 1R1 2 3 2R3 1 3 6Is1 2 0 15AIs2 2 3 15A.DC Vs2 LIST 20V.PRINT DC V(3).OP.END
thevenin.cir
Determination of output Resistance
321
0
+
-
Vs15V
R36 ohm
R12 ohm
R51 ohm
Vs2 1 0 0VR5 1 2 1R1 2 3 2R3 1 3 6VS1 3 0 5V.DC Vs1 LIST 5V.PRINT DC V(3) +I(VS1).OP.END
thevenin.cir
Find the Norton Equivalent of the circuit to the left of the points a and b
0
1 2 3+
-
v
+
-
v1 1/4 V1R4
8 ohmR36 ohm
R21 ohm
R12 ohm
+
-
Vs13V
0
1+
-
vR6
8 ohmR5
1.82 ohm
Is10.675A
a
b
a
b
Determination of short circuit current
v1
-
+
321
0
isc|v
1/4 V1+
-
Vs13V
R36 ohm
R21 ohm
R12 ohm
v1
-
+
321
0
isc|v
+
-
Vs20V
1/4 V1+
-
Vs13V
R36 ohm
R21 ohm
R12 ohm
Vs1 1 0 3VR1 1 2 2R2 2 3 1R3 2 0 6Vs2 3 0 0VG1 3 0 2 0 0.25.DC Vs1 LIST 3V.PRINT DC I(Vs2).OP.END
norton.cir
Determination of output Resistance
v1
-
+
32
0
+
-
Vs25V1/4 V1
R36 ohm
R21 ohm
R12 ohm
Vs1 1 0 0VR1 1 2 2R2 2 3 1R3 2 0 6Vs2 3 0 5VG1 3 0 2 0 0.25.DC Vs2 LIST 5V.PRINT DC I(Vs2) +V(3).OP.END
norton.cir
.PARAM
Defines the value of a parameter. A parameter name can be used in place of most
numeric values in the circuit description. Parameters can be constants, or expressions
involving constants, or a combination of these, and they can include other parameters.
Examples .PARAM VSUPPLY = 5V
.PARAM VCC = 12V, VEE = -12V.PARAM BANDWIDTH = 100kHz/3
.STEP
The .STEP command performs a parametric sweep for all of the analyses of the circuit.
General form .STEP LIN <sweep variable name> <start value>
+<end value> <increment value>
Examples
.STEP VCE 0V 10V .5V
.STEP LIN I2 5mA -2mA 0.1mA
.STEP LIN PARAM Res .5k 10k .5k
Example – Plot the variation in power absorbed by load R2 as it varies between 500Ω and 10kΩ. When is it the maximum ?
VS1 1 0 DC 5VR1 1 2 5kR2 2 0 Res.PARAM Res 4K.STEP LIN PARAM Res .5k 10k .5k .DC VS1 LIST 5V.PROBE.OP.END
param.cir
Source: http://www.tdpcb.com/images/pcb6.JPG