High linear and efficient RF CMOS power amplifiers with transmission line transformer

Abstract

Growth in the wireless communication market in recent years has been driving the demand for higher integration of CMOS wireless transceivers in order to achieve lower cost, smaller form factor, and more functionalities. Much recent research effort has demonstrated the feasibility to integrate most transceiver building blocks into a single CMOS die. One of the few remaining blocks that have yet to be successfully integrated is the Power Amplifier (PA). The PA is usually the last active building block in a radio transmitter. Its function is to amplify the signal power up to the required level before it can be transmitted into the air. Due to several limitations of CMOS technology, designing a linear and efficient PA is a challenging task. This thesis is divided into two parts First part includes a fully integrated CMOS power amplifier with a half-turn transformer for IEEE 802.11a WLAN applications. The circuit is operated for a 3.3V operation with 0.18μm CMOS technology. To combine output power, an on-chip transmission line transformer (TLT) is used. The maximum power is 23.8dBm and the power added efficiencies are 18.8% at $P_{1dB}$ and 20.1% at $P_{sat}$, respectively. When a 54 Mbps/64 QAM OFDM signal is applied, the PA delivers average power of 12dBm at an EVM of -25dB. Second part introduces the proposed Quasi-Doherty CMOS power amplifier with Integrated-Passive Device (IPD) transformer for WCDMA applications. Since the Quasi-Doherty PA can improve the PAE at the medium power level, such a technique is very useful for WCDMA/WLAN system which require a high PAE at the medium power level. A quadrature 3-dB hybrid coupler at input network can be replaced by asymmetric power divider that is on-chip CMOS die, ant this asymmetric power divider can be integrated with Doherty power amplifier. This configuration is compact enough to minimize the circuit size of Doherty power amplifier, providing good isolation between output ports. It is worthwhile to note that...