High Pass FIR Filters and and Zero placement.

Cuthbert Nyack

High pass FIR filters using zero placement are illustrated below. What was said for Low Pass also applies here.

In the pass band, the zeros are assumed to be on either side of the unit circle and on the unit circle in the stop band.
The numerical values of the zeros are shown on the right, Zr is the magnitude and Zp * 2p is the phase. The plot of the impulse response assumes the same number of poles at the origin as the number of zeros.
The pink line shows a magnified plot of the frequency response in the pass band with gain controlled by the last scrollbar and shown as mpb(63).

Images below show some possibilities.
In the cases below, the transition bandwidth is 0.08 w_s, the scale for the pink line is 1dB/div and the pass band ripple is ~0.1dB. The stop band attenuation varies between 50 and 70dB.

A band pass version of this approach is shown below.

Return to main page
Return to page index