Distortion Analysis Using Volterra Series and Linearization Technique of Nano-Scale Bulk-Driven CMOS RF Amplifier

Abstract

The distortion analysis of nano-scale bulk-driven (BD) CMOS RF amplifier is presented based on Volterra series. The first three-order Volterra kernels are computed; and the closed-form expressions of the second-order and third-order harmonic distortion (HD) are derived. These expressions give good accuracy comparing with the simulation results, and can provide insight into the nonlinearity of nano-scale BD amplifier. These expressions unveil and demonstrate that the nano-scale BD MOSFET has distinct nonlinear characteristics. Also, distortion-aware design guidelines for nano-meter CMOS BD amplifier are provided. A modified second-order intermodulation (IM2) injection technique is presented to suppress the third-order intermodulation (IM3) product. This modified technique which consumes only 64 μA current employs phase adjustment of the low-frequency IM2; and up to 20 dB IM3 reduction is achieved over 1 MHz-20 MHz two-tone spacing range without gain reduction or noise penalty.