Piecewise Linear (and Piecewise Step) Sources

Apr 13 2012, 6:30 PM PDT · 0 comments »

As another facet of our Arbitrary Behavioral Sources release, we've now added support for voltage and current sources to generate piecewise linear or piecewise step signals inside the simulator. This allows you to inject the specific signals you need to test your circuit.

The PWL, PWS, PWLREPEAT, and PWSREPEAT expressions (described in the documentation) take lists of time/value pairs, so you can describe any function you want, and let the simulator interpolate between control points if desired.

Take a look at this Capacitively Loaded Emitter Follower demo which uses a PWL voltage source:

The PWLREPEAT function used to define V2 sets up a pulse that has both postive-going and negative-going parts, with defined edge slopes between the two and the off-state. Open the circuit and run the time-domain simulation to see the piecewise-linear source in action, summed with the +2.5V static bias to produce the voltage waveform V(in). Then, take a look at the V(out) trace, and you'll see that an emitter follower isn't always great at following signals with large, quick changes!

Piecewise sources, plus our new behavioral sources, expose the power of the CircuitLab simulation engine and make it easier to apply CircuitLab to your specific engineering design problems.


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