SAW waveguide-coupled resonator notch filter

A unique implementation of a SAW (surface acoustic wave) notch filter using a two-pole waveguide-coupled (WGC) resonator in an allpass network is presented. This configuration exhibits a dramatic improvement in the bandwidth of the notch over the single-pole approach. This application of the two-pole WGC resonator design is discussed in detail, and results of a two-pole design at 193 MHz are presented. A cascaded four-pole resonator notch filter at 193 MHz with low passband loss and broadband notch depth greater than 40 dB is demonstrated. This notch filter is shown to be easy to tune, and exhibits excellent temperature characteristics.<>