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Group Delay of Active or Passive BPF (Read 51 times)

vermouth

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Group Delay of Active or Passive BPF
Apr 05^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?

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August West

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Re: Group Delay of Active or Passive BPF
Reply #1 - 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].

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