Design Of Envelope Tracking Power Amplifier For Multi-mode Multi-standard Transceiver

With the progress of wireless communication technology and the expansion of its applications, new communication modes and standards are constantly emerging. To meet the different needs in people’s life, a radio frequency (RF) transceiver which supports for multiple communication standards is indispensable. In order to deliver high data rates, the more spectral-efficient non-constant envelope modulation schemes are adopted in new technology, and the signal dynamic range and the peak-to-average power ratio (PAPR) are greatly improved. Traditional power amplifier (PA) designed by power back-off method cannot achieve high efficiency and difficult to meet the requirements of portable devices for energy consumption. Therefore, the design of a RF power amplifier which supports multiple complex communication standards, with high integration, high linearity, high efficiency has important research significance and practical value.In this thesis, an envelope tracking power amplifier based on TSMC 0.18μm CMOS process was designed, which can meet the application requirements of multiple communication standards in 1.85-2.7GHz band, and the average efficiency was improved. The system mainly includes an envelope detector, an envelope modulator and a broadband class AB amplifier. Envelope detector extracts the RF signal envelope, envelope modulator tracks the amplitude of the input signal dynamically and then supplies the voltage of PA to improve its efficiency. As the core module of the system, the power amplifier employs a two-stage linear amplifier structure, and implemented with the technique of lossy networks, matching compensation, and multi-stage network with low Q factor, meets the requirements of indicators in wide-band range. According to the post-simulation results, in the working frequency band of 1.85-2.7GHz,the proposed PA achieves maximum output power of more than 24dBm, average power gain is over 20dB.The OPi1dB is more than 21.8dBm,and the power added efficiency (PAE) at OP1dB is over 21.2%.The simulated S11 is under-15dB and achieved good input matching feature. When inputs the non-constant envelope LTE 16QAM 5MHz signal and CDMA signal, the average power added efficiency of power amplifier reached 21%,and the overall average efficiency of ETPA system is over 11%,increased by 5%-7% than the fixed voltage condition, achieved the goal of efficiency enhancement.The designed envelop tracking power amplifier has a wide working band, increased the average efficiency when high PAPR signals input, and applicable to a variety of wireless communication standards. It can be applied in the multi-mode transceiver systems which require high efficiency and linearity by further optimization.