I am attempting to come up with a systematic way to design Multiple Feedback bandpass filters with certain specifications.(adsbygoogle = window.adsbygoogle || []).push({});

• Frequency is some given number

• Bandwidth varies with Frequency by

f0*2^13/12

• The Q should therefore be .4719

• The gain should be 1

I am at an understanding of how to manipulate Frequency and Q (BW follows), but I am having trouble finding information on how to manipulate gain. I am using the following topology:

http://sound.westhost.com/articles/af-f6.gif

With that background, which may prove irrelevant to my actual question, how is the gain for this MFB calculated? Rod Elliott, the author of the above picture, claims that that happens to be a unity gain filter, but does not explain why this is so.

I read a TI note that gave a gain formula for an MFB, but it was a slightly different design. The formula was a simple resistor ratio. Can anyone figure out the gain for this one?

I may have more questions after I sleep on it. Thanks in advance everyone.

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# MFB Filter Gain Formula

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