Design of wide band transversely coupled resonator filters on quartz

Abstract

Typical relative bandwidth of transversely coupled resonator filters (TCRF) on quartz wafers varies between BW =0.05 to 0.1%. In this paper, we investigate the factors restricting the bandwidth and describe some specific features of designing TCRF with more expanded bandwidth BW =0.15-0.3%, on quartz. The results of investigation are illustrated by experimental characteristics of four TCRF types: 315 MHz filter with BW =0.28%, 248 MHz filter with BW =0.18%, 402 MHz filter with BW =0.125% and 360 MHz filter with BW =0.064%. All filters are manufactured on quartz wafer, cut 33.3°-YX, in packages SMD 3.8x3.8x1.4 mm.