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

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.

[1]  C. M. Andersson,et al.  A SiC Varactor With Large Effective Tuning Range for Microwave Power Applications , 2011, IEEE Electron Device Letters.

[2]  J. Sonsky,et al.  Innovative High Voltage transistors for complex HV/RF SoCs in baseline CMOS , 2008, 2008 International Symposium on VLSI Technology, Systems and Applications (VLSI-TSA).

[3]  Christian Fager,et al.  An inverse class-F GaN HEMT power amplifier with 78% PAE at 3.5 GHz , 2009, 2009 European Microwave Conference (EuMC).

[4]  F. Raab,et al.  Power amplifiers and transmitters for RF and microwave , 2002 .

[5]  Dominique Schreurs,et al.  A robust integrated multibias parameter-extraction method for MESFET and HEMT models , 2000 .

[6]  Robert H. Caverly,et al.  HF, VHF, and UHF systems and technology , 2002 .

[7]  Sudhakar Pamarti,et al.  A power amplifier with minimal efficiency degradation under back-off , 2010, Proceedings of 2010 IEEE International Symposium on Circuits and Systems.

[8]  F. Raab,et al.  Radio Frequency Pulsewidth Modulation , 1973, IEEE Trans. Commun..

[9]  Michael Faulkner,et al.  Performance Analysis of Pulse Width Modulated RE Class- E Power Amplifier , 2006, 2006 IEEE 63rd Vehicular Technology Conference.

[10]  Christian Fager,et al.  High Efficiency Radio Frequency Pulse Width Modulation of Class-E Power Amplifiers , 2012 .

[11]  H. Sjoland,et al.  Two 130nm CMOS class-D RF power amplifiers suitable for polar transmitter architectures , 2008, 2008 9th International Conference on Solid-State and Integrated-Circuit Technology.

[12]  Frederick H. Raab,et al.  Idealized operation of the class E tuned power amplifier , 1977 .

[13]  H. Zirath,et al.  Design of Varactor-Based Tunable Matching Networks for Dynamic Load Modulation of High Power Amplifiers , 2009, IEEE Transactions on Microwave Theory and Techniques.

[14]  Anne-Johan Annema,et al.  Generalized Analytical Design Equations for Variable Slope Class-E Power Amplifiers , 2006, 2006 13th IEEE International Conference on Electronics, Circuits and Systems.