Bandpass filter resonator network improves insertion loss with isolating/buffer amplifiers

摘要

The bandpass filter network uses multiple acoustic resonators 12, 14, 16, 18 in a series/shunt configuration. The resonators may be thin-film bulk acoustic resonators (FBARs) or surface acoustic wave resonators (SAWs). The resonators are isolated from each other by one or more amplifiers 20, 22, 24, 26. This arrangement is said to improve insertion loss in the resonators. The amplifiers may be of the cascode type using NMOS transistors, and the resonators may be coupled between individual stages of the amplifiers (see figs 3 & 5). The filter will find use in a wireless radio receiver operating in or near the ISM 2.4 band.