A fully integrated dual-mode CMOS power amplifier for WCDMA applications

Integrating a CMOS RF power amplifier (PA) into a single-chip transceiver is one of the most challenging works in implementing radio front-ends, which presents many advantages in handheld applications [1,2]. Especially, low-power efficiency enhancement (LPEE) techniques, considering the probability distribution function of the practical wireless communication environments, extend the battery lifetime in handheld devices [1–3]. Therefore, there are many studies for the LPEE in handheld CMOS PAs [1,2] using transmission-line transformers (TLTs) with parallel amplifiers. Designing a series/parallel-combining transformer (SCT/PCT) is one of the key factors in the implementation of a dual-mode CMOS PA. However, the dual-mode performances of the PA must be optimized by using one output TLT structure. It is expected that there are difficulties in designing a highly efficient dual-mode PA. Therefore, this paper introduces a fully integrated dual-mode CMOS PA with a proposed output TLT with 2 control switches, which allows an LPEE with a back-off region of 10dB or more with a very low quiescent current.