Integrated receive filter including matched balun

摘要

A duplexer includes a transmit filter and an integrated receive filter configured to filter a receive signal from an antenna. The integrated receive filter includes a receive filter portion having multiple acoustic resonator filter elements and a matched balun configured to convert a single-ended input signal, received at a single-ended input of the matched balun from a single-ended output of the receive filter portion, to a differential output signal. The matched balun being is located in place of a phase matching inductor of the receive filter portion, eliminating need for the phase matching inductor of the receive filter portion and a phase matching inductor of the matched balun. Impedance at the single-ended input of the matched balun includes a complex conjugate of impedance at the single-ended output of the receive filter portion.

主权项

1. A duplexer comprising:
a transmit filter configured to filter a transmit signal from a transceiver; and an integrated receive filter configured to filter a receive signal from an antenna, the integrated receive filter comprising:
a receive filter portion comprising a plurality of acoustic resonator filter elements to provide a filtered signal at a single-ended output; anda matched balun coupled to the single-ended output of the receive filter portion and configured to convert the filtered signal at the single-ended output of the receive filter portion to a differential output signal,wherein the matched balun is further configured to match the single-ended output using an input impedance comprising a complex conjugate of an output impedance of the single-ended output of the receive filter portion, andwherein the input impedance of the matched balun matches the output impedance of the single-ended output of the receive filter portion without a phase matching inductor in either the matched balun or the receive filter portion.