High efficiency RF pulse width modulation with tunable load network class-E PA

MUSTAFA ÖZEN; Christer Andersson; Mattias Thorsell; Kristoffer Andersson; Niklas Rorsman; Christian Fager; M. Acar; M. P. Van Der Heijden; R. Jos

doi:10.1109/WAMICON.2011.5872869

High efficiency RF pulse width modulation with tunable load network class-E PA
Paper in proceeding, 2011

In this paper, a 10 W peak power 2 GHz highly efficient RF pulse width modulation (RF-PWM) based transmitter is presented. RF-PWM signals are generated with a dedicated 65 nm CMOS modulator and subsequently amplified with a GaN Class-E power amplifier (PA). The modulator use extended drain MOS (EDMOS) high voltage transistors to provide the required voltage swing to drive the GaN used as a switch. The imaginary load impedance of the Class-E is electronically tunable and is implemented with in-house high breakdown voltage SiC varactors. The tunable imaginary load impedance enables optimization of the Class-E versus the duty cycle (pulse width). The peak efficiency is therefore preserved over a wide range of output power levels. The measured drain efficiency of the Class-E output stage is above 70% over a 6.5 dB output power dynamic range. The overall transmitter efficiency is above 60% for the same dynamic range.

RF-PWM

SiC varactors

power amplifiers

high efficiency

EDMOS

pulse width modulation

Class-E