Unit suffixes in PSPICE

The Unit suffixes in P Spice are as follows.
V = Volts
A = Amps
HZ = Hertz
OHM = Ohm(O)
H = Henry
F = Farad
DEG = Degree.

In the absence of scale and unit suffixes, the unit of voltage, current, frequency, inductance, capacitance and angle are, by default, volt, amps, hertz, henrys, farads, and degrees, respectively. P Spice ignores any unit suffix.

25E-3 25.0E-3 25M 25MA 25MOHM 25MH

NOTE:-The scale suffixes are all upper case, but PSpice allows lower case.
M Means “milli,” not “mega” 2MO is written as 2MEG or 2MEGOHM

Options in PSPICE

.OPTIONS (Options)
P Spice allows various options to control and to limit parameters for the various analysis. The general form is
.OPTIONS [ <(options)name>] [ <(options)name>=]
the options can be listed in any order. There are two types of options
1. With out values (used as flags of various kinds, and only option name is mentioned
2. With values (used to specify certain optional parameters, name and their values) as given below.

Option(with out values) Effects
LIST Causes summary of all circuit elements (or devices) tobe output
NOPAGE Suppresses paging and printing of a banner for each major section
NODE Causes out put of net list
Option (with values) Effects Unit Default

TNOM Default Temperature Degrees°C 27
ITL1 DC and Bias Point “blind” Iteration limit 40
ITL2 DC and Bias Point “educated guess” Iteration limit 20
ITL4 Iteration limit at any point in Transient analysis 10
ITL5 Total Iteration limit for all points in Transient analysis 5000
(ITL5=0 means ITL5=infinite)
RELTOL Relative Accuracy of voltages and currents 0.001
TRTOL Transient Analysis accuracy adjustment 7.0
ABSTOL Best Accuracy of currents Amps 1pA
CHGTOL Best Accuracy of charges coulomb 0.01Pc
VNTOL Best Accuracy of voltages volt 1uV
GMIN Minimum conductance used for any branch Ohm-1 1E-12

Circuit elements and their symbols - PSPICE

Circuit elements and their Symbols
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 Current Source
H Current Controlled Voltage Source
I Independent Current Source
J Junction Field effect transistor
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.

Types of analysis in PSPICE

Types of Analysis
PSpice allows various types of analysis. Each analysis is invoked by including its command statements.
Ex:-.DC command invoked the DC Sweep.
DC Analysis is used for circuits with time variant sources(ex:-steady state dc source ).
It calculates all node voltages and branch currents over a range of values ,and their quiescent(dc)values are the outputs.
Command Meaning
1..DC DC Sweep of an input voltage or current source ,a model parameter ,or temperature over a range of values
2..OP Determination of the linearized model parameters of non linearized devices.
or DC Operating Point or Quiescent Point or Bias Point.
3..TF Small Signal Transfer Function with small signal Gain, input resistance, and output resistance.
4..SENS DC Small signal sensitivities.
5..TRAN Transient analysis with time variant sources It calculates all node voltages and branch currents over a time interval ,and their instantaneous values are the out puts
6.(.) dot an integral part of the command.

It can perform various analyses which invoked by including its command statements .It always calculates the bias point, which consists of all node voltages as well as currents and power dissipation of all voltage sources can be sent tot the output file by the .OP Command

Limitations in PSPICE

Limitations of P Spice .
1. It is restricted to circuit with 10 Transistors only.
2. With out editing the program, the circuit cannot be analyzed for various component values; means the program is not interactive.
3. P Spice does not support an iterative method of solution.
4. It cannot be used to synthesize the circuit elements
5. The input impedance cannot be determined directly with out running the. PROBE.
6. Distortion analysis is not available in P Spice.
7. The out put impedance of a circuit cannot be printed or plotted directly.

Advance commands and analysis - PSPICE

Sources in a circuit are time variant .They are alternative current, or ac, and have both magnitude and phase displacement. Practical sources are generally sinusoidal or nearly sinusoidal. The behavior of a circuit is normally evaluated with sinusoidal source .The steady state voltages and currents that are normally used to evaluate the performance of a circuit can be calculated by applying the circuit laws that are applicable to d circuits. The Transient behavior is also important under some conditions, but the analysis becomes more complex compared to steady state analysis.
In this type of circuit generally input is sinusoidal source, and their circuit elements are R,L and C, and the voltages & currents are expressed in phaser quantities .For example;
V = V m ∟Φ
Inductance (L) and capacitor (C) are expressed as impedances:
Z L = j2πL = jω
In ac analysis, the output variables are sinusoidal quantities and are represented by complex numbers. An Output variable can have magnitude in decibels, phase, group delay, real part, and imaginary part .
SUFFIX MEANING
M Peak Magnitude
DB Peak Magnitude IN Decibels
P Phase in Radians
G Group Delay (∆PHASE / ∆ FREQUENCY)
R Real Part
I Imaginary Part

Voltage Output

Variables Meaning
VM (5) Magnitude of Voltage at Node 5 with respect to Ground
VM (4, 2) Magnitude Voltage at Node 4 with respect to Node2
VDB (R1) DB Magnitude of Voltage across Resistor R1, where the first Node (as defined in the circuit file) is positive w.r.t second Node.
VP (D1) Phase of Node Voltage of diode D1 with respect to Cathode.
VCM (Q3) Magnitude of the collector Voltage of Transistor Q3, w.r.t ground
VDSP (M6) Phase of the drain source voltage of MOSFET M6 w.r.t ground
VBT (T1) Phase of voltage at port B of Transmission Line T1
VR (2, 3) Real part of voltage at node 2 w.r.t Node 3
VI (2,3) Imaginary part of voltage at node 2 w.r.t Node 3



Current Output
Variables Meaning
IM (R5) Magnitude of Current through Resistor R5
IR (R5) Real Part of current through Resistor R5
II(R5) Imaginary part of Current through Resistor R5,
IM(VIN) Magnitude of Current through Source Vin
IR(VIN) Real Part of current through Source Vin
II (VIN) Imaginary part of Current through Source Vin
IAG(T1) Group Delay of current at Port A of Transmission Line T1

P Spice Variables Meaning
V2 VM (2) Peak Magnitude of Voltage at Node 2
∟ V2 VP (2) Phase angle of Voltage at Node 2
V 1,2 VM (1, 2) Peak Magnitude of Voltage between Nodes 1& 2
∟ V 1,2 VP (1, 2) Phase angle of Voltage between Nodes1& 2
IR IM (VX) Magnitude of Current through voltage source Vx
∟IR IP (VX) Phase angle of Current through voltage source Vx
IL IM (L1) Magnitude of Current through Inductor L1
∟IL IP (L1) Phase angle of Current through Inductor L1
IC IM (C1) Magnitude of Current through capacitor C1
∟IC IP (C1) Phase angle of Current through capacitor C1

Types of Output commands in PSPICE

1. .PRINT The result from dc analysis can be obtained in the form of table
Example:-print statement .PRINT DC (Output variables)
We will get output variables, maximum up to 8 values

2. .PLOT The result from dc analysis can also be obtained in the form of line printer plots. The plots are drawn by using characters, and the result can be obtained from any kind of printer.
Example:-plot statement .PLOT DC (Output variables) +
[{(Lower Limit) value}, (Upper limit) value}]
We will get output variables, maximum up to 8 values

The range and increment of the x-axis is fixed by the dc analysis command.
The range of the y-axis is set by adding [{(Lower Limit) value}, (Upper limit) value}]
At the end of the .PLOT statement .it can be placed in the middle of a set of o/p variables.
If the y-axis range is omitted, P Spice assigns a default range determined by the range of the output variables.
Example:-.PLOT statement .PLOT DC V(2) , V(3,5), V(R1), I(Vin) , I(R1)

3. .PROBE Probe is a Graphical wave form analyzer
Example statements:-
.PROBE where no output variables is specified, it writes all node voltages and all the element currents.
PROBE OUTPUT

.PROBE V(5),V(4,3), I(R2) where the output variables are specified ,PSpice writes only the specified out put variables to the PROBE .DAT file.
In the statement we have to write ‘m’ for milli not to write as MIL ;
M for mega , not to write as MEG
If a dc voltage source VS is connected between nodes 2 and 3,the plot of the trace(or curve) = V(2,3) * I(VS) will give the power delivered by the source VS