A feedforward power amplifier with loops to reduce RX band noise and intermodulation distortion

This article proposes a new power amplifier approach for the reduction of amplified noise signals in the receiver (RX) band as well as intermodulation distortion signals in the transmitter (TX) band using a feedforward technique. The proposed power amplifier, which contains two loops, the TX band intermodulation distortion cancellation loop and the RX band noise cancellation loop, can provide a duplexer with low transmit path insertion loss by choosing a small receive attenuation characteristic. A two-tone test for the power amplifier is done at 2.14 GHz with a frequency spacing of 5 MHz. A 31 dB reduction for the intermodulation distortion signals is obtained. Experimental loop tests show that the cancellation performance of TX band intermodulation distortion signals and RX band noise signals are more than 26 dB and 30 dB over the entire TX and RX bands, respectively.