Antenna duplexer circuit with a phase shifter on the receive side

Abstract

A high frequency wireless circuit apparatus is formed by connecting a phase shifter between an antenna duplexer and a low noise amplifier, so that the impedance of the receiving terminal of the antenna duplexer at a transmission frequency and the input impedance of the low noise amplifier may not be matched in complex conjugates of each other. Therefore it prevents the transmission output passing through the receiving terminal of the antenna duplexer and the interference signal entered through the antenna from making the cross modulation in the low noise amplifier. Thus it improves the reception sensitivity and immunity to interference signals of the high frequency wireless circuit apparatus at the same time.

Dependencies are inferred from the claim text.