60% high-efficiency 3G LTE power amplifier with three-level delta sigma modulation assisted by dual supply injection

This paper presents a new power amplifier architecture incorporating a multi-level envelope delta sigma modulation (EDSM) encoder together with a dynamic bias control method to improve the overall efficiency. The proposed transmitter was developed based on a 3-level encoding process for quantizing the non-constant envelope signal. Therefore, the power amplifier is always operated under only a two-state output power level (maximum and 6dB back-off levels), achieving high efficiency. To maintain this high efficiency at a 6dB back-off output level, a lower DC supply voltage is supplied from a dual supply network (DSN) assisted on a digital process block. Using the proposed efficiency enhancement method, we have designed and implemented a 2.6GHz high-efficiency Class-J power amplifier (PA) using a commercial 10W PEP GaN device and a simple dual supply network. The experimental results show that, if the 0.51dB power loss of the band pass filter is de-embedded, the proposed power amplifier delivers a drain efficiency (DE) of 59.8% and power added efficiency (PAE) of 55.6%, with a gain of 11.1dB at an average output power of 34.5 dBm, for a 10 MHz 3G LTE signal with a 8.5 dB peak-to-average power ratio (PAPR).