Smart MMIC power amplifier with adaptive control circuit for wireless mobile terminals

Abstract

The concept of a multi-band multi-mode RF transceiver continues to attract a number of wireless mobile terminal users who demand a single terminal for international roaming services. Most of RF transceiver circuits are implemented with CMOS: thus, multi-band transceivers are underway that can be implemented in a single chip CMOS. However, as of now, the linear power amplifier is not yet able to be integrated with CMOS. As such, more research of the multi-band power amplifier is needed separately. Both efficiency and linearity are critically required in power amplifiers for non-constant envelop digital modulation mobile terminals. Even though the efficiency of the power amplifier reveals a maximum value of around 40% at the linearity limit, because the most frequently used power level ranges from -20 dBm to 15 dBm, backed-off from the linearity limit, the average efficiency of the power amplifier significantly decreases to a value of around 5 %. Thus, this thesis focuses on the two most important issues in MMIC (monolithic microwave integrated circuit) power amplifier for 3G and beyond wireless mobile communications: the improvement of average power usage efficiency and single chip multi-band power amplifiers. MMIC power amplifiers in two of the most important applications are studied in this work: the high efficiency power amplifier for WCDMA (wideband code division multiple access) terminals with a new dynamic bias controller, and a single-input dual-output amplifier with a switched input matching circuit for the multi-band multi-mode WLAN (wireless LAN). First, thesis presents an InGaP/GaAs HBT smart MMIC power amplifier equipped with a new dynamic bias controller and dual power stages in parallel. The proposed dynamic bias circuit controls the quiescent current as a function of input power with absolute freedom, and is implemented in a WCDMA MMIC power amplifier together with the parallel power stages to ensure both linearity and efficiency. The dual power...