A CMOS Amplifier with Third-Order Intermodulation Distortion Cancellation

A 2.4 GHz CMOS amplifier with third-order intermodulation distortion cancellation is presented based on the derivative superposition technique. The proposed circuit uses a conventional amplifier topology followed by a distortion cancellation circuit that can significantly improve third-order linearity. To quantify the linearity improvement, two general-purpose amplifiers were fabricated and measured: (1) a traditional cascode amplifier and (2) an identical cascode amplifier followed by a distortion cancellation circuit. The new amplifier increases the IP3 by approximately 12 dB without having a significant effect on either the gain or noise characteristics of the original amplifier.