I came across that SVF filter at that site a while ago and (after of course translating it to VHDL) I promptly expanded the test jig with more input waveforms and implemented all filter type outputs. So as inputs I can select noise, sqware, sine and sawtooth and for outputs I can select lowpass, bandpass, highpass and notch (band stop).
I dug up the test code and made a
to show what it can do. The parameters of the filter are, fsample=800Khz, Q=1 and you can clearly see that even at Q=1 it still amplifies the signal at the filter's cut off frequency. Due to the internal number representation use I cannot lower the Q any more and of course increasing the Q will cause even more amplification to the point of overdriving the output (causing math overflows).
There are no comments to display.
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.