I have an unusual low-pass filter problem that I would like to realise with a passive RC network (Note 1).
I am having difficulty finding prototype filters for the classic filter types (e.g. Butterworth, Chebychev, Elliptic) that are implemented using such a network. The closest I have managed to find is this which recommends equal R and C values for each passive in the network:
Hence, I would like to ask
- Is there a good reference that covers this sort of design?
- Are there any "tricks" or "gotchas" for this design?
- What is the design procedure to implement one of the classic filters?
Note 1 - Context:
The design is for a second-order low-pass anti-aliasing filter. A first order doesn't attenuate an annoying periodic glitch enough - and I may yet need a higher-order filter. Board space is very limited and the ADC has a built-in buffer that I would like to make use of. The attenuation is desirable - the signal is larger than the ADC would normally accept. Inductors are completely undesirable for the application.