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

Packaged integrated low-pass quasi-load insensitive (QLI) class-E matching is proposed for the realization of energy-efficient 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.