ACTIVE BAND-PASS PIEZOELECTRIC FILTER Russian patent published in 2008 - IPC H03H9/54 H03H11/12 

FIELD: electricity.

SUBSTANCE: device contains the first and the second piezoelectric resonators, first inputs of which are connected to input potential filter terminal, and the second outputs of specified piezoelectric resonators through the first and second resistors are connected respectively to global bus, the first, second and third operational amplifiers, each of which contains resistive negative feedback. Output of the first operational amplifier is filter output, inverting and noninverting inputs of the first operational amplifier through the fourth and fifth resistors are connected to outputs of the second and the third operational amplifiers respectively, besides, noninverting input of the first operational amplifier through the third resistor is connected to global bus, inverting inputs of the second and third operational amplifiers are interconnected through the sixth resistor, and noninverting inputs of specified operational amplifiers are connected to the second outputs of the first and the second piezoelectric resonators respectively. Between filter input and noninverting inputs of the second and third operational amplifiers the first and second groups containing each one N-1 piezoelectric resonators are connected.

EFFECT: provided continuous frequency response with varying amplification factor and device enhancement.

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