MULTI-CHANNEL ACTIVE PIEZOELECTRIC FILTER Russian patent published in 2010 - IPC H03H9/54 

FIELD: electricity.

SUBSTANCE: multi-channel active piezoelectric filter containing the adder with two inputs and two outputs, which is made on two operational amplifiers with negative feedbacks, to the inverting input of the first and the second operational amplifiers there connected is the first and the second resistor, the second outputs of which are connected to common bus; inverting input of the first operational amplifier through the third resistor and non-inverting input of the second operational amplifier through the fourth resistor are connected to the first input of adder; non-inverting input of the first operational amplifier through the fifth resistor and inverting input of the second operational amplifier through the sixth resistor are connected to the second input of adder; non-inverting inputs of the first and the second operational amplifiers through the seventh and the eighth resistors are connected to common bus respectively; at that, outputs of the first and the second operational amplifiers are the first and the second outputs of adder; to input potential terminal of filter there connected is the first and the second group of piezoelectric resonators, each of which includes N piezoelectric resonators; to the first output of adder there connected is the third group consisting of N piezoelectric resonators; to the second output of adder there connected is the fourth group consisting of N piezoelectric resonators; at that, to each of the second outputs of piezoelectric resonators of the third and the fourth groups there connected are two resistors, and one of them is connected with its second output to common bus, and the second outputs of the other resistors are connected to each other in pairs so that to each pair there connected is one of the resistors connected to one of piezoelectric resonators of the third group and the other resistor connected to one of piezoelectric resonators of the fourth group; each of the pairs of the above resistors is connected to one of potential output terminals of filter which also includes the third and the fourth inverting operational amplifiers with negative feedbacks; output of the first operational amplifier is connected to the first adder input; output of the fourth operational amplifier is connected to the second adder input; to input of the third operational amplifier there connected are N resistors the second outputs of which are connected to the second outputs of piezoelectric resonators of the first group; to the input of the fourth operational amplifier there connected are N resistors the second outputs of which are connected to the second outputs of piezoelectric resonators of the second group.

EFFECT: enlarging pass band at big number of channels.

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