MULTIPLE-RESONATOR PIEZOELECTRIC BAND FILTER Russian patent published in 2002 - IPC

FIELD: radio electronics; signal frequency selection. SUBSTANCE: filter has first transformer 1 incorporating two windings of which first one has two leads with first lead connected to filter input potential terminal and second winding has N + 1 leads with N ones connected to first group of N piezoelectric resonators; second transformer 2 incorporating two windings of which first one has two leads and second winding has M + 1 leads, M ones being connected to second group of M piezoelectric resonators. First lead of first winding of second transformer 2 is connected to input potential terminal of filter; second leads of first group 3 incorporating N piezoelectric resonators are integrated and connected to (N + 1)-th lead of second winding of first transformer 1 whose first-winding second lead is connected through first resistor 5 to common bus. Second leads of second group 4 composed of M piezoelectric resonators are integrated and connected to (M + 1)-th lead of second winding of second transformer 2 whose first-winding second lead is connected through resistor 6 to common bus and through third resistor, to inverting input of operational amplifier 7; noninverting input of the latter is connected through fourth resistor 9 to first lead of second resistor 6 and through fifth resistor 10, to common bus. Output of operational amplifier 7 is connected to output potential terminal of filter. EFFECT: improved filter linearity. 1 dwg