ACTIVE BAND-PASS PIEZOELECTRIC FILTER Russian patent published in 2001 - IPC

FIELD: radio electronics. SUBSTANCE: active and-pass piezoelectric filter is equivalent to two-section filter. Each section is built on symmetric bridge circuit. Filter includes first, second, third and fourth piezoresonators 1, 2, 3, 4 with capacitors 5, 6, 7, 8 connected in parallel. First leads of first and second piezoresonators 1, 2 are tied up together and present input of filter, second leads of these filers are correspondingly connected to non- inverting inputs of first and second operational amplifiers enveloped by negative resistive feedbacks 9, 10 and to first leads of first and second resistors 11, 12 whose second leads are linked to common bus. Inverting inputs of negative resistive feedbacks 9, 10 are connected with the aid of additional resistor 13. Outputs of first and second negative resistive feedbacks 9, 10 are connected to leads of third and fourth piezoresonators 3, 4. Second lead of third piezoresonator 3 is connected to first leads of third and fourth resistors 14, 15 and second lead of fourth piezoresonator 4 is connected to first leads of fifth and sixth resistors 16, 17. Second leads of third and fifth resistors 14, 16 are connected to common bus. EFFECT: diminished filter noise, possibility of usage of piezoelectric filter with practically any values of dynamic inductance. 2 dwg