The Designer's Guide Community Forum

The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl
Design >> Analog Design >> Group Delay of Active or Passive BPF
https://designers-guide.org/forum/YaBB.pl?num=1081216242

Message started by vermouth on Apr 5^th, 2004, 6:50pm

Title: Group Delay of Active or Passive BPF
Post by vermouth on Apr 5^th, 2004, 6:50pm

Hi, everyone

These days I am working over the group delay of BPF. I found that so few books or papers talked about it. I am doing some simulations on BFSK demodulating system, which consists of a BPF and a demodulator, and I met the following problem:
The the group delay of the BPF is very important to the final BER. But how to improve this property of a filter? As I know, to active filter, adding a phase equalizer is a good way. Are there any other resolutions? And what about the passive ones?

Title: Re: Group Delay of Active or Passive BPF
Post by August West on Apr 5^th, 2004, 7:38pm

I suspect that you want to design for maximally flat delay over frequency. That way it looks most like simple delay and there is the least distortion of the waveshape. A filter with maximally flat envelope delay (MFED) is referred to as a Bessel or a Thompson filter [W.E. Thomson, "Delay Networks Having Maximally Flat Frequency Characteristics," Proc. IEEE, part 3, vol. 96. Nov 1949, pp. 487-490].

-August