Wideband low loss SAW filters for telecommunication and mobile radio applications

The possibility of utilizing cuts of LiNbO/sub 3/ with high piezoelectric coupling for leaky waves-41/spl deg/-YX and 49/spl deg/-YX-in wideband SAW filters, has been demonstrated. The equivalent circuit model was modified for longitudinally coupled resonator filters and some second-order effects have been taken into account to improve the accuracy of filter simulation. Thick Al electrodes are used to increase the effective electromechanical coupling. Spurious SAW signals are suppressed by the frequency shift between filter cascades. Low-loss (2-3 dB) two-cascade filters with bandwidths 6-7% and high sidelobe suppression (60 dB), more typical for three-cascade filters, were designed and manufactured.