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Often, you want to see the effect of changing multiple parameters on the performance of your design. For example, you might want to know how the gain or bandwidth of a design is affected when you vary multiple components across a range of values. Sometimes, the variation of the component values can also be nested - varying a component for each changed value of another component. In simple words, you want to sweep a design to determine the relationship of parameter variations to performance. You can use Parametric Plotter to sweep any number of design and model parameters in any combinations and view results in Plot/Probe in a tabular or plot form.
You need to determine the answers to the following three questions before you start with parametric plots: What performance you want to measure, which components you will vary and in what order, and how you will vary the value of the components?
Most often the choice of components to be swept and the performance being measured are closely tied to each other. For example, on running transient analysis on a circuit, overshoots or spikes are seen and it is observed that the spikes can be reduced by increasing the values of a resistor and a capacitor in the circuit. However, increasing the value leads to power dissipation across the resistor. The measurements will then be overshoot and power dissipation against the resistor and the capacitor values.
Once you have identified the components, you can vary the values using any of the following four sweep types:
You will use the RF Amplifier demo design (File – Open – Demo Designs) in OrCAD® Capture to follow along with the steps. If you are using another design, you might want to run a transient simulation or AC analysis and create the measurements of interest in PSpice A/D. You can also create measurements in PSpice Advanced Analysis.
To specify sweep types, do the following:
There will be a total of 100 simulations as each parameter will be swept for 10 values.
You will observe the effect of value change on the bandwidth and gain of the circuit. You can either import measurements created in PSpice A/D by clicking the text Click here to import a Measurement created within PSpice or right-click and choose Create New Measurement.
You can also add a plot to show the relationship between parameters and measurements graphically.
To add a plot, do the following steps:
This concludes our series on Advanced Analysis. You can refer to the following earlier posts:
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The (P)SpiceItUp series provides solutions to analog and mixed-signal simulation and analysis-related tasks performed using PSpice A/D or PSpice Advanced Analysis. Our vision, as reflected by the logo and the title of this series, is to make the critical simulation and analysis activities easy and enjoyable. Our regular new blog posts cover every aspect of analysis and simulation, including modeling and schematic design preparation.