Small-sized 71 MHz GSM-IF filter using SAW resonator on Li/sub 2/B/sub 4/O/sub 7/ substrate

A small package size and low loss filter for GSM-IF have been developed with SAW resonators on LBO substrate. For realizing low loss of about 43 dB and very steep slope over 50 dB at +/-700 kHz offset from center frequency, the filter is composed of 4-pole resonator filter which consists of two cascaded IDT type DMS resonator filters. Each DMS filter is a longitudinally coupled resonator and uses withdrawn electrode technique of the IDT attached to suppress the spurious response. The filter is mounted in 9.1/spl times/48 mm ceramics package even for 71 MHz.