Linearization of mixers using predistortion and envelope signal injection

This letter presents a new linearization method for mixers employing predistortion and envelope signal injection. In this technique the third order intermodulation distortion (IM3), at the output of a mixer in IF band, was cancelled by using a diode predistortor and injecting the envelope of the RF input signal to both the predistortor and the mixer. By properly adjusting the amplitude and polarity of the injected envelope signal, up to 26 dB improvement of the IM3 is obtained in a two tone test with 100 kHz separation at 1.9 GHz. This method operates very well over a wide range of output power up to the 1 dB compression point of the mixer.