Amplifier linearization in a radio frequency system

An amplifier linearization circuit assembly for reducing intermodulation distortion in an amplifier, the amplifier linearization circuit assembly comprising:

• a difference frequency circuit configured to receive a first signal including a first frequency and a second frequency and to generate a second signal having a frequency approximately equal to the difference of the first frequency and the second frequency, when received at an input terminal of an amplifier, the first signal generating first intermodulation products between the first and second frequencies in an output signal of the amplifier;
• a power detector configured to detect a power level of the first signal;
• and
• an envelope adjustor configured to adjust a magnitude of the second signal without feedback of the output signal and based at least in part on the detected power level of the first signal and a tuned slope of a shaping function, the adjusted signal configured to be applied to a second terminal of the amplifier to generate second intermodulation products with the first signal that cancel at least a portion of the first intermodulation products.

A wireless communication device comprising:

• an antenna configured to receive and transmit radio frequency signals;
• a transceiver configured to provide the antenna with radio frequency signals for transmission and to receive from the antenna radio frequency signals for processing, the transceiver including an amplifier configured to amplify a radio frequency input signal, the amplifier including an input configured to receive the radio frequency input signal and an output configured to provide an amplified radio frequency signal;
• and
• an apparatus configured to reduce intermodulation distortion in the amplifier, the apparatus including a difference frequency circuit configured to receive the radio frequency input signal that includes a first frequency and a second frequency and to generate a second signal having a frequency approximately equal to the difference of the first frequency and the second frequency, a power detector configured to detect a power level of the radio frequency input signal, and an envelope adjustor configured adjust an amplitude of the second signal without feedback of the amplified radio frequency signal and based at least in part on the detected power level of the radio frequency input signal and a tuned slope of a shaping function, the amplifier further including a drain terminal configured to receive the envelope-adjusted signal to cancel at least a portion of intermodulation products from the amplified radio frequency signal.