OrCAD PSPICE – DC Parametric Sweeps

DC Parametric Sweeps:


It is also possible to vary the parameters in a DC-swept fashion. Common examples of parameters that can be varied include resistance, capacitance, transistor Beta, and so on.
A good example of this is to demonstrate the maximum power transfer theorem, where the  load resistance of a circuit must equal the source resistance in order to get maximum power into the load.

1. Create a new project called “power” and add a schematic to the project as follows. Note that the value of R2 is {RLOAD}, which will refer to a global parameter.


2. Place a new part on the drawing called “PARAM” (from the SPECIAL library.) Place it on the schematic, then double-click its body to open its property sheet. Within the property sheet editor, make the following changes to the PARAM block:

• Select the “OrCAD-PSpice” Filter to make it easier to see the important fields.

Filter• Click the “New Column” button and add a column called RLOAD. Set its value to 1k, as shown below.

New Column• Make sure to set RLOAD visible by highlighting it and clicking the “Display” button.

• Close the property sheet. Your drawing should now have a parameter block that
looks something like this:

property sheetThe value of 1k has no effect on a DC swept analysis, but will instead be used for bias point (steady-state) calculation (if that is required).

3. Edit the analysis profile to look like this:

analysis profile

The sweep will vary the global parameter you named — RLOAD — in accordance with the rules set forth under “Sweep type.”

4. Run the analysis with F11. Solid State Circuit Analysis

OrCAD PSPICE can model circuits with mixed analog and digital components. Below is a common-emitter amplifier. Using PSPICE simulation we can determine:

• What are the DC operating voltages of the amplifier?
• What is the voltage gain and compliance of the amplifier?
• What is the frequency response of the unit?

1. Start a new project called “transistor” and insert the circuit of the amplifier below.


2. Create a new simulation profile and set it as follows:

simulation profileNote that the VSIN source in the circuit is set to 1 KHz, and that the analysis steps are
1µS — so there will be 1000 calculations for each sine wave cycle. With the TSTOP
setting of 10 mS, we should see 10 cycles of the waveform on the display.

3.  Run the simulation. To see the DC voltages and currents, click the appropriate toolbar

#PSPICE Seminar / DeVry KC – Spring 2002

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