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Wednesday, July 9, 2008

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