Software-defined radio with broadband amplifiers and antenna matching

摘要

Mobile phone handsets include a CMOS front end configured for operating across multiple transmit and receive frequencies. The front end typically includes multiple receivers, each covering a different band allocated for cellular service, and requires large, expensive and power-intensive A/D converters and DSPs. Front-end circuits disclosed herein operate with a broadband software-defined radio (SDR), and include a receive Low Noise Amplifier (LNA), transmit Power Amplifier (PA), and an antenna matching network. The front-end provides broadband operation using relatively low power, and minimizes noise in the received signal.

主权项

1. A circuit comprising:
a transmit path connecting a transceiver to an antenna; a receive path connecting the transceiver to the antenna, the receive path coupled to the transmit path at a common node; a power amplifier (PA) coupled to the transmit path, the PA configured to amplify a transmit signal from the transceiver and output an amplified transmit signal to the antenna; a differential low noise amplifier (LNA) coupled to the receive path, the differential LNA configured to receive a received signal from the antenna and a signal corresponding to the transmit signal, the differential LNA outputting an amplified received signal, wherein the signal corresponding to the transmit signal is an equalized transmit signal; a receive detector configured to detect noise at an output of the differential LNA; a feedback circuit configured to output the equalized transmit signal to the differential LNA; a controller coupled to the feedback circuit, the controller configured to adjust at least one of a gain and a phase of the equalized transmit signal based on an output of the receive detector; and a transmit detector configured to detect the transmit signal, the controller further configured to adjust at least one of the gain and the phase of the equalized transmit signal based on the output of the transmit detector.