Design of a Power Amplifier and Envelope Amplifier for a Multi-band Multi-standard Envelope Tracking System
This thesis presents the design of a Power Amplifier (PA) and envelope amplifier for an Envelope Tracking (ET) system that is aimed at meeting emerging radio standards in terms of power efficiency and linearity. The class J mode of operation, as well as the efficiency and power contours from load pull was exploited to develop an adequate procedure for the design of a broadband and high efficiency radio frequency PA. An in-depth study has also been conducted for a hybrid envelope amplifier topology in order to optimize it for power efficiency through proper setting of its switching stage supply. Two separate proof of concept prototypes of the PA and envelop amplifier were designed, fabricated and tested. The PA designed was able to achieve an average drain efficiency of 73.6%, average output power of 45.89dBm, and an average gain of 18dB between 650MHz and 1.050GHz (48% bandwidth). The envelope amplifier achieved close to 74.6% efficiency for a 5MHz bandwidth LTE signal envelope with 6.4dB peak to average power ratio.