Programmable bandpass using twin-t bridge

Posted on Sep 12, 2012

The circuit gives a programmable bandpass where both the cut-over frequency and the gain, A, are controlled independently. In the twin-T bridge the resistors R and R/2 are replaced by two double FETs, 430, the channel resistance of the first one in the series, the channel resistances of the second one are in parallel as to stimulate the resistance R/2. Both these resistors are controlled by Vc which ranges from 0 V to about 1 V.

Programmable bandpass using twin-t bridge
Click here to download the full size of the above Circuit.

The gain of the circuit is set by means of the resistors R2 and R3.

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