All content Copyright 2022 Parallel Systems Ltd.

 

A typical application of Monte Carlo analysis is predicting yields on production runs of a circuit board. Probe can be used to display data derived from Monte Carlo waveform families as histograms, which is part of Probe’s performance analysis feature.

 

This Chebyshev filter is designed to have a 10kHz centre frequency and a 1.5 kHz bandwidth. The components were rounded to the nearest available 1% resistor and 5% capacitor values. In our analysis, we are concerned with how the bandwidth and the centre frequency vary when 1% resistors and 5% capacitors are used in the circuit.

 

Tolerances are added using the Tolerance Part Property. The models then get defined as:

 

.model RMOD RES R=1 DEV=1%

.model CMOD CAP C=1 DEV=5%

 

To analyse the filter, an AC analysis with a Monte Carlo analysis will be configured. The AC analysis sweeps 50 points per decade from 100Hz to 1 MHz and the Monte Carlo analysis is set to take 100 runs. The output variable of interest is V(OUT).

 

The data file can become quite large when running a Monte Carlo analysis. Since only the output of the filter is of interest, a voltage marker will be placed at the output, and then the simulation set up to collect data at the marked node only.

 

1. Open the provided Cheby project from the C:\OrCAD_Training\PSpice directory.

 

2. Run the simulation.

The Probe window opens, select all the results and the output response will be displayed (because of the Voltage probe at the OUT node)

 

3. Use View>Output File, at the end of the Output File are the sorted deviations from Nominal. The parameters for each run are list throughout the file. Run 1 is the “Nominal values” simulation run.

 

 

 

 

End of Lab

 

 

All content Copyright 2022 Parallel Systems Ltd.