A multimode/multiband envelope tracking transmitter with broadband saturated power amplifier

Abstract

A multimode/multiband envelope tracking (ET) transmitter consisting of a hybrid switching amplifier (HSA) and a broadband saturated power amplifier (PA) is developed across 1.3 to 2.7 GHz. For the various standard signals with different bandwidth and peak-to-average power ratio, the HSA efficiently provides a supply signal to the PA by changing the reference value of the hysteresis comparator. The broadband saturated PA, taking advantage of a nonlinear output capacitor to shape the voltage waveform, is implemented based on load/source-pull methodology. Broadband matching networks for the high efficiency are synthesized by simplified real frequency technique. For the bandwidth from 1.3 to 2.7 GHz (70% fractional bandwidth), the measured output power, drain efficiency, and power-added efficiency (PAE) performances are between 39.8–42.0 dBm, 55.8–69.7%, and 51.2–65.3%, respectively. The ET transmitter is demonstrated at 1.8425-GHz long-term evolution (LTE), 2.14-GHz wideband code division multiple access (WCDMA), and 2.6-GHz mobile world wide interoperability for microwave access (m-WiMAX) applications. It delivers the PAE of 32.16, 37.24, and 28.75% for LTE, WCDMA, and m-WiMAX applications, which are improved by 3.1, 4.2, and 1.7%, respectively.