Multilevel Power Supply for High-Efficiency RF Amplifiers

In communication systems, linear power amplifiers (PAs) (class A, B, or AB) are usually used as a solution for the PA stage. These amplifiers have high linearity, but suffer from low efficiency when the transmitted signal has high peak-to-average power ratio. The Kahn envelope elimination and restoration technique is used to enhance the efficiency of RF transmitters by combining highly efficient, nonlinear RF amplifier (class D or E) with a highly efficient envelope amplifier in order to obtain linear and highly efficient RF amplifier. This paper presents a solution for the envelope amplifier based on a combination of multilevel converter and linear regulator. The proposed solution can reproduce any signal with maximum spectral component of 2 MHz and give instantaneous maximum power of 50 W. The efficiency measurements show that when the signals with low average value are transmitted, it has up to 49% higher efficiency than an ideal linear regulator that is used as a conventional solution. Additionally, the algorithm for the optimization of the voltage levels, for the multilevel converter, is explained as well.

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

[2]  D. C. Cox,et al.  Improving the Power-Added Efficiency of FET Amplifiers Operating with Varying-Envelope Signals , 1983 .

[3]  J.A. Cobos,et al.  Power supply for a radio transmitter with modulated supply voltage , 2004, Nineteenth Annual IEEE Applied Power Electronics Conference and Exposition, 2004. APEC '04..

[4]  O. Garcia,et al.  Digital-Control-Based Solution to the Effect of Nonidealities of the Inductors in Multiphase Converters , 2007, IEEE Transactions on Power Electronics.

[5]  Eduard Alarcón,et al.  Effects of switching power converter nonidealities in envelope elimination and restoration technique , 2006, 2006 IEEE International Symposium on Circuits and Systems.

[6]  Seth R. Sanders,et al.  Optimum Bias Calculation for Parallel Hybrid Switching-Linear Regulators , 2007, APEC 07 - Twenty-Second Annual IEEE Applied Power Electronics Conference and Exposition.

[7]  Frederick H. Raab,et al.  RF and Microwave Power Amplifier and Transmitter Technologies — Part 1 , 2003 .

[8]  F. Raab,et al.  L-band transmitter using Kahn EER technique , 1998 .

[9]  F. Raab.  Intermodulation distortion in Kahn-technique transmitters , 1996 .

[10]  H.J. Bergveld,et al.  A 50MHz bandwidth multi-mode PA supply modulator for GSM, EDGE and UMTS application , 2008, 2008 IEEE Radio Frequency Integrated Circuits Symposium.

[11]  M. Hoyerby,et al.  Ultrafast Tracking Power Supply With Fourth-Order Output Filter and Fixed-Frequency Hysteretic Control , 2008, IEEE Transactions on Power Electronics.

[12]  V. Yousefzadeh,et al.  Three-level buck converter for envelope tracking applications , 2006, IEEE Transactions on Power Electronics.

[13]  Walter L. Morgan,et al.  Principles of Communications Satellites , 1993 .

[14]  V. Yousefzadeh,et al.  Three-level buck converter for envelope tracking in RF power amplifiers , 2005, Twentieth Annual IEEE Applied Power Electronics Conference and Exposition, 2005. APEC 2005..

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

[16]  Pallab Midya,et al.  Tracking power converter for supply modulation of RF power amplifiers , 2001, 2001 IEEE 32nd Annual Power Electronics Specialists Conference (IEEE Cat. No.01CH37230).

[17]  J.W. Kolar,et al.  A multi-cell cascaded power amplifier , 2006, Twenty-First Annual IEEE Applied Power Electronics Conference and Exposition, 2006. APEC '06..

[18]  F. H. Raab,et al.  High-efficiency single-sideband HF/VHF transmitter based upon envelope elimination and restoration , 1994 .

[19]  Eduard Alarcón,et al.  Efficiency optimization in linear-assisted switching power converters for envelope tracking in RF power amplifiers , 2005, 2005 IEEE International Symposium on Circuits and Systems.

[20]  George B. Norris,et al.  High efficiency CDMA RF power amplifier using dynamic envelope tracking technique , 2000, 2000 IEEE MTT-S International Microwave Symposium Digest (Cat. No.00CH37017).

[21]  Christophe Garnier,et al.  A Single-Chip WCDMA Envelope Reconstruction LDMOS PA with 130MHz Switched-Mode Power Supply , 2008, 2008 IEEE International Solid-State Circuits Conference - Digest of Technical Papers.