Broadband Linearization Technique for mmWave Circuits

Abstract

This paper presents a broadband linearization technique that can be used for mmWave amplifier circuits. It is based on the well-known principle of derivative superposition, where FETs with different operating points are connected in parallel to generate mutually cancelling third order intermodulation distortion (IM3) products. It is demonstrated by measurements in excess of 10 dB improvement in IM3 obtained from 1 GHz to 30 GHz, practically free by connecting a NMOS with very low gate bias in parallel of an amplifying NMOS. The reasons and limits of the cancellation are discussed. The inherent broadbandness of the technique makes it extremely suitable to be used in CMOS mmWave circuits.