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Re: Pease tuneable MFB band-pass filter

 

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The bandwidth is constant, so the Q varies with frequency. I agree that the tuning range is restricted if R2 isn't varied over a very wide range, because the peak frequency is proportional to sqrt(R2).

It is interesting to regard it as a bridged-T.

On 2025-05-11 16:24, Jerry Lee Marcel via groups.io wrote:
This circuit is basically an inverter with a bridged-T in the feedback. Since it has only one variable element, the amplitude of the peak and the BW (some say "Q") vary. Its usage is usually reserved for applications where the tuning range is restricted.
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