Need help on PSpice Lab? This document deals with most of the problems faced in the lab. It has suggestions to help you ace the exams, and practice problems and solutions

The idea to make this thing was given by Rajat Chakraborty Sir,
Lecturer, Department of EEE, BUET. Much of them has been told by
sir in class during our 2-1 Pspice lab.

Prepared by: Ridwan Abrar.
Thanks to Partho Ghosh for his ideas as well.



Common mistakes/ errors in Pspice:
1. Make sure to use Ic = 0, this cancels the transient part
2. For transient response, set the step ceiling to 1u (1 microseconds),
Otherwise the graph gets wriggly around the maxima/ minima
3. For i-v characteristics, make sure you measure voltage across the
diode. The voltage across the source is given as default, make
sure to change that!
4. Make sure the appropriate junctions are shorted in a MOSFET
5. While drawing a MOSFET, take extra care to look at which of the
two terminals is shorted. You may need to rotate and flip in order
to match the figure.
6. Always use frequency sweep in decade mode
7. There is a voltage drop of 0.579 V in the diode in Pspice, so do
your calculations accordingly before setting a clipper or clamper
circuit.
8. Never forget to add ground!
9. Always use ‘Vsin’ as a source when you’re doing transient analysis
(meaning you need a graph which has ‘t’ in the x-axis. and use
“V​ac​” for frequency responses (meaning you need a graph which
has “frequency” in the x-axis
10.While drawing the rectifier circuits/ clipper or clamper circuit,
take extra care about the voltage or diode nodes (I always mess
those things up). To have a perfect graph of the clipper circuit,


Prepared by Ridwan Abrar, BUET EEE ‘16

, fine tune the DC voltage sources in between 0.1-1 Volts and do
not touch any other part of the circuit (if fine tuning in this
region is not working for you, then you definitely have drawn the
wrong circuit for the given problem.)
11. Take output across emitter
12. Adjust ranges to ensure that the full graph appears
13. Do not use MAX function. Use frequency sweep for analysis
14. V​sin​ for transient , V​ac​ for frequency sweep
15. No change in V​CE​ for fixed and self-bias circuits. V​CE​ vs I​C
16.MOSFET: The middle wire is the gate
17. R​break​ = R*10k
18. PMOS and NMOS arrows are switched in Pspice
19.To find the phase difference Phase(Vin) - Phase (Vout)
20. LOG() => log base e
21. Log10 () => log base 10
22. Bandwidth, BW = w​2​ - w​1​ = w​H​ - w​L
23.

Lectures on Diode:




V​P​ > V​n​ => Forward biased
V​P​ < V​N​ => Reverse biased

In case of a bridge rectifier:


Prepared by Ridwan Abrar, BUET EEE ‘16

,Sweep range in Pspice:
-150 ---> +15 (voltage sweep)




-V​i​ + V​DO​ + V​o​ = 0
=> V​o​ = V​i​ - V​DO



Prepared by Ridwan Abrar, BUET EEE ‘16

, V = Voltage across a diode = Change in axis settings under probe
window.
If the PIV is low, then it is better.




Clipper:
This one cuts in the positive half cycle:




Prepared by Ridwan Abrar, BUET EEE ‘16