High Efficiency and Wide Bandwidth Quasi-Load Insensitive Class-E Operation Utilizing Package Integration

Abstract

Packaged integrated low-pass quasi-load insensitive (QLI) class-E matching is proposed for the realization of energyefficient wideband Doherty and outphasing transmitters. In view of this, a dedicated QLI class-E harmonic matching technique, suitable for in-package integration has been developed, optimized, and evaluated. As proof of concept, very compact, as well as easy to assemble, dual-input load-modulating transmitters have been realized. In this paper, we focus on a QLI class-E matched wideband Doherty that provides 71% peak efficiency (±3%) at 48-dBm saturated output power and 49% (±7%) efficiency at 6-dB power backoff, over a 1200-MHz frequency span (1.4-2.6 GHz), yielding 60% fractional bandwidth (BW). When tested with single-carrier long-term evolution (LTE) signals, having a 7-dB peak-to-average ratio, average efficiency remains close to 49% (±3%) for the entire 60% fractional BW. The realized demonstrator shows excellent linearizability with adjacent channel power ratio and normalized mean square error levels below −50 dBc and −36 dB, respectively, even when operated in simultaneous dual-band LTE operation.Index Terms-Doherty, dual input, harmonic matching, high efficiency, package integration, quasi-load insensitive (QLI) class-E, wideband.

A Highly Linear Wideband Polar Class-E CMOS Digital Doherty Power Amplifier

“…The total drain capacitance (C D , including the transistors and interconnect parasitics) is tuned for class-E operation at ACW M (ACW P ) = ACW M P,M ax . Therefore, when the main (peak) DPA is fully on, it operates in class-E. As the number of switching transistors in the main (peak) DPA decreases (at PBO), the fundamental impedances become complex with positive reactances, and the second harmonic impedances become mostly negative reactances (capacitive), thus operating similar to a class-J PA [43]- [45]. For small ACW M (ACW P ) ( < 30), the voltage swing on drain of the main (peak) DPA is small, therefore operating similar to a current source with an almost linear behavior [17].…”