Surface acoustic wave filter bank having trap function

Abstract

The invention relates to a surface acoustic wave filter bank having a trap function, which comprises a one-level surface acoustic wave filter bank and a gate circuit, wherein the one-level surface acoustic wave filter bank comprises a group of broadband surface acoustic wave filters and two groups of single-pole multi-throw switches; the two groups of single-pole multi-throw switches are respectively electrically connected with an input end or an output end of the group of broadband surface acoustic wave filters; the two groups of single-pole multi-throw switches are in one-to-one correspondence; the gate circuit is respectively electrically connected with the two groups of single-pole multi-throw switches; an input end or an output end of the one-level surface acoustic wave filter bank isconnected with at least one surface acoustic wave trap filter in series; the surface acoustic wave trap filter is formed by connecting two one-terminal pair surface acoustic wave resonators which areconstructed on a piezoelectric substrate with an external inductor according to an n-shaped circuit; and the two one-terminal pair surface acoustic wave resonators are respectively positioned on twoparallel arms of the n-shaped circuit. The surface acoustic wave filter bank has small volume and low consumption, and realizes high inhibition on the specific frequency signals.

Description

technical field [0001] The invention relates to a switchable surface acoustic wave filter group, in particular to a surface acoustic wave filter group with notch function applied in radar. technical background [0002] The switchable surface acoustic wave filter bank that can realize the program control function is needed for frequency hopping communication and frequency-agile radar: one is to select frequency in the frequency synthesizer; the other is to do anti-interference filtering in the receiver. In the application of the receiver, the received signal is generally very weak. In order to reduce the energy consumption of the system, the filter bank is required to have a low insertion loss; in order to suppress the strong interference signal and ensure the signal-to-noise ratio of the system, a single filter is required. There is a smaller squareness factor and higher stopband rejection; and in order to specifically remove signals in a certain frequency range, higher reje...

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But SAW notch filters are rarely used in SAW filter assemblies

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