PIEZOELECTRIC ACTIVE BAND FILTER Russian patent published in 2002 - IPC

FIELD: radio electronics; signal frequency selection. SUBSTANCE: filter has first and second resistors 1 and 2 whose first leads are connected to filter potential input terminal; two structurally identical sections 8, 9 each incorporating operational amplifiers 10, 11, 13; first and second piezoelectric resonators 15, 16. First resonator 15 is inserted between output of operational amplifier 10 and input of operational amplifier 13 whose feedback circuit incorporates capacitor 14. In addition filter has adder 3 built around negative-feedback operational amplifier 4, as well as third, fourth, and fifth resistors 5, 6, 7. Output of operational amplifier 13 is connected through second resonator 16 to inverting input of operational amplifier 11 whose output is connected through sixth resistor 12 to inverting input of operational amplifier 10; output of the latter is connected in first section to first input of adder 3 and in second section, to second input of adder 3. EFFECT: enhanced stability to variations in parameters. 1 dwg