A broadband Rx band noise reduction circuit with CMOS switch for multi-band power amplifier

A broadband Rx band noise reduction circuit for multi-band power amplifiers (PA) is presented. The proposed Rx band noise reduction circuit consists of a Single-Pole Double-Throw (SPDT) switch and an LC resonator with resonant frequency is at the difference frequency between transmit and receive bands. By controlling the connection path of the LC resonator with the SPDT switch, the proposed Rx band noise reduction circuit achieves broadband Rx band noise suppression. In this paper, to clarify the impact of the proposed circuit, the proposed circuit is applied to a multi-band PA. As a result, the proposed Rx noise reduction circuit offers broadband out-of-band noise suppression and improved Rx noise power. In addition, the PA achieves more than 28.5 dBm of output power with power added efficiency (PAE) as high as 37% with a corresponding Rx-noise power of −136.5 dBm/Hz.