Table of Contents
International Journal of Microwave Science and Technology
Volume 2009, Article ID 597592, 9 pages
http://dx.doi.org/10.1155/2009/597592
Research Article

Analysis and Compensation of the AM-AM and AM-PM Distortion for CMOS Cascode Class-E Power Amplifier

1Department of Electronics Engineering, National Chiao Tung University, 1001 Ta Hsueh Road, Hsinchu 30010, Taiwan
2SOC Technology Center, ITRI, 195 Section, 4 Chung Hsing Road, Chutung, Hsinchu 30040, Taiwan

Received 1 September 2009; Revised 19 November 2009; Accepted 12 December 2009

Academic Editor: Liang-Hung Lu

Copyright © 2009 Wen An Tsou et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Analysis and compensation methodology of the AM-AM and AM-PM distortion of cascode class-E power amplifiers are presented. A physical-based model is proposed to illustrate that the nonlinear capacitance and transconductance cause the AM-AM and AM-PM distortion when modulating the supply voltage of the PA. A novel methodology that can reduce the distortion is also proposed. By degenerating common-gate transistor into a resistor, the constant equivalent impedance is obtained so that the AM-AM and AM-PM distortion is compensated. An experimental prototype of 2.6 GHz cascode class-E power amplifier with the AM-AM and AM-PM compensation has been integrated in a 0.18 m CMOS technology, occupies a total die area of 1.6 . It achieves a drain efficiency of 17.8% and a power-added efficiency of 16.6% while delivering 12 dBm of linear output power and drawing 31 mA from a 1.8 V supply. Finally, a co-simulation result demonstrated that, when the distortion of the PA has been compensated, the EVM is improved from −17 dB to −19 dB with an IEEE802.11a-like signal source.