Dual-power-mode quasi-doherty RF CMOS power amplifiers for mobile communications

Abstract

Dual-power-mode (DPM) quasi-Doherty RF CMOS power amplifiers (PAs) for mobile communications are presented. Considering probability density function, to achieve long battery life-time in a mobile phone, two architectures for the DPM PA are proposed using SOI LDMOS and (SOI) CMOS processes, respectively. Firstly, in the SOI LDMOS PA, second harmonics are controlled through the path of low power mode (LPM) for high pow-er mode (HPM) PA’s linearity. In addition, a capacitor added switch is proposed to increase its voltage standing capability, which is used at the output matching network for a mode control. A combined cascode structure of CMOS and LDMOS devices for the LPM is pro-posed to complement two devices’ drawbacks. Secondly, in the DPM CMOS PA, a trans-former-based quasi-Doherty PA (QDPA) is designed for the HPM. In the QDPA, a folded combining transformer is proposed for three advantages: reduced chip area, improved inser-tion loss, and increased bandwidth. Furthermore, an adaptive power divider is proposed for adjustable power dividing according to the incoming power in the input of the QDPA. In the LPM, only main power cell in the QDPA turns on. Its cell-size in the common gate transistor is controlled using an adaptive power cell (APC) technique, which is used for a PA’s linearity improvement in the HPM.