Follow along with the video below to see how to install our site as a web app on your home screen.
Note: This feature may not be available in some browsers.
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.
I know VHDL very well. And i know it is fully digital.
But how i can model an RC circuit?
You could always use a FIR filter to implement that RC low pass.
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.But how i can model an RC circuit?
yn = yn-1 *(1-a) + xn * a; a ≈ T/RC
You can't. not with normal VHDL. For simulating analog circuits you should use VHDL-AMS. It is easy to learn but not every compiler can handle AMS.