RF Power Amplifier Efficiency Enhancement

Bachelor thesis (2017)

Authors

B. Bouazzata Electrical Engineering, Mathematics and Computer Science
D.J.H. van der Kolk Electrical Engineering, Mathematics and Computer Science

Contributors

S.M. Alavi (supervisor 1)
M.J. Pelk (supervisor 1)
L.C.N. de Vreede (supervisor 1)
Faculty
Electrical Engineering, Mathematics and Computer Science
Copyright: © 2017 Bilal Bouazzata, Niels van der Kolk
RF Power amplifier PA
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Published Date

26-07-2017

Language

English

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Faculty

Electrical Engineering, Mathematics and Computer Science

Abstract

In this thesis, a new RF Power Amplifier design is proposed that targets for improving the efficiency profile of classical RF Amplifiers. This RF Power Amplifier is especially designed for modulation schemes that need a PA with high PAPR. The PA consists of two different stages that will be digitally controlled. One of these stages has an optimized efficiency profile for supporting input signals with nominal power and the other stage has an optimized efficiency profile for supporting input signals with peak power. The PA has been designed with GaN HEMT's which perform very well at high frequencies while delivering high power.

The PA has been designed to perform optimally for frequencies around 100 MHz. Simulations show that at peak power, which is 40 dBm for this amplifier design, the PA has an efficiency of 63.5%. At 6 dB power back-off, the PA has an efficiency of 65.5%. The PA has a gain of approximately 20 dB at peak power level and approximately 18 dB at nominal power level. Furthermore the stability of the PA is optimized for the carrier frequency of the input signal. At 100 MHz the Rollet Stability Factor K is of magnitudes higher than unity which guarantees the stability of the circuit.

Furthermore a PCB has been developed to do some investigations in how this new PA design will perform in practice. Measurements on this PCB show that in power back-off a maximum efficiency of 63% can be reached. Results of the performance at peak power show that the efficiency reaches a maximum level of 37%. A possible reason for this is insufficient suppression of undesired harmonics.