Verilog-A can model digital devices as well as analog. This is useful in situations where some simple logic function interfaces mostly with analog elements. An example is a phase detector in a phase-locked loop. At least one of its inputs would often come from an analog source and its output would usually drive a low-pass filter also implemented with analog components. Some phase detector designs employ a digital state machine that would usually suit a digital event driven simulator. But if it interfaces with analog devices, interface bridges would need to be connected to the analog signals. This complicates and slows down the simulation. Using Verilog-A we can efficiently implement the entire function in the analog domain.
We have provided an example of a phase detector; see Examples/phase_detector.
In this section we will show how to create some simple logic elements.
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