Sometimes you want to model external analog circuits in a digital signal processing test bench. If you are e.g. designing a PID controller, you may add a control system or "plant" model to your simulation. A first order low pass is a simple model example. It's first order differential equation can be represented by a difference equation.
As in all digital signal processing applications, the VHDL signals are still digital.
Sometimes you want to model external analog circuits in a digital signal processing test bench. If you are e.g. designing a PID controller, you may add a control system or "plant" model to your simulation. A first order low pass is a simple model example. It's first order differential equation can be represented by a difference equation.
As in all digital signal processing applications, the VHDL signals are still digital.
Question: How can you design a SD ADC without knowing about z-transformations and difference equations? As far as I'm aware of, digital signal processing text books are discussing the relation between time-discrete and time-continuous systems, difference and differential equations, z- and s-domain description.
well the AMS family, verilog-AMS and VHDL-AMS, are languages designed to simulate analog, digital and mixed signal circuits. they are not much different from the normal verilog and VHDL, though not synthesizable. the problem is that the conventional compilers can not handle AMS family. The ones I know which can support AMS are a special version of modelsim and mentor. I have worked with menor and have simulated some mixed signal circuits. it works perfectly.
I agree, that the circuit can be perfectly simulated with VHDL AMS. It's particularly good for complex mixed signal designs.
But you shouldn't create the impression that AMS is the only tool that can give meaningful results for this simple circuit. Including time discrete models of the analog circuit in a digital VHDL testbench works well and will be surely suffcient for the present problem.