Switchable low loss SAW filter bank with SAW notch filters

The design and testing of 4 channels switchable low loss SAW filter bank with SAW notch filters is described. Slanted-finger interdigital transducer (SIDT) including EWC/SPUDT is adopted to achieve the low insertion loss of individual SAW filter. SAW filters are fabricated on YZ LiNbO₃ substrate with the insertion loss of less than 6.5 dB, the stop-band rejection of more than 40 dB, the 1 dB bandwidth of more than 9 MHz and the 40 dB bandwidth of less than 15 MHz. Switches are added to both input and output of SAW filters and two SAW notch filters are separately connected to the input and output of the switches. SAW notch filters are fabricated on Y36deg LiTaO₃ substrate with the rejection of more than 30 dB and the insertion loss of less than 0.5 dB. The experimental filter bank results in the insertion loss of 7.5 dB, the stop-band rejection of more than 40 dB, and the rejection more than 60 dB at the frequency through the stop-band of the SAW notch filter.