Compact low loss IF balanced bridge filters

Balanced bridge SAW impedance element filters (BBF's) developed recently have some important advantages such as wider passband, better suppression in the stopband, small size when compared with coupled resonator filters (CRF's). Compared to ladder type IEF's, a balanced bridge network gives lower insertion loss in passband, better suppression in the stopband and allows balanced input/output operation. The geometrical and COM parameters were found close to optimal to decrease size, technological sensitivity and suppress spurious signals. To avoid high level of feedthrough, care must be taken to provide the filter layout being also balanced with respect to parasitic capacitances.