P6G-3 Switchable SAW Filter Bank with Both Narrow & Wide Channel Bandwidth and 10 Channels SAW Filter Bank

The design and testing of 8 channels and 10 channels low loss switchable SAW filter bank is described. There are both narrow & wide channel bandwidths in 8 channels filter bank. The 1 dB bandwidth of narrow channel is about 0.3% and that of wide channel more than 3.2 MHz. Cascade-connected two stages are constructed to achieve higher stop-band rejection. Every narrow bandwidth channel is constructed with two same SPUDT SAW filter on ST-X quartz with insertion loss less than 6 dB and stop-band rejection more than 40 dB. Each wide bandwidth channel includes of a fan-type SPUDT filter on X-112degY LiTaO₃ with insertion loss less than 10 dB and a longitudinally-coupled DMS filter on 36degY-X LiTaO₃ less than 2 dB. The experimental 8 channels SAW filter bank results in insertion loss less than 12.5 dB and stop-band rejection more than 70 dB. In 10 channels filter bank, the individual filter consists of fan-type SPUDT on X-112degY LiTaO₃ with insertion loss of less than 12 dB, stop-band rejection more than 40 dB, magnitude ripples in pass-band less than 0.5 dB and nonlinear phase less than 2deg per 1 MHz. The experimental 10 channels filter bank results in insertion loss of 14.6 dB, deviation of insertion loss among different channels less than 0.5 dB, and stop-band rejection more than 40 dB.