High-efficiency Power Amplification Techniques for Wireless Transmitters
Doktorsavhandling, 2010

The low efficiency of existing power amplifiers (PAs) is causing excessive energy consumption in wireless systems. Improving the PA efficiency is therefore of great environmental and economical importance. This thesis address a wide range of advanced PA design methods and novel PA architectures that all contribute to significantly improve the efficiency of PAs for wireless applications. The first part of the thesis addresses the design of PAs with high peak efficiency. A transistor modeling technique for first-pass design of switched-mode and harmonically tuned PAs is proposed. Using the proposed modeling technique, optimization of harmonic impedances, and employing bare-die transistors, a state-of-the-art power-added efficiency (PAE) of 80% is achieved for 1-GHz LDMOS and 3.5-GHz GaN-HEMT PAs at 10 W and 7 W output powers, respectively. Another PA with a current mode class-D topology is also designed at 1 GHz using a packaged LDMOS transistor and its commercially available model. A PAE of 69% and gain of 15 dB is achieved at an output power of 20 W. In addition, by investigating the effect of harmonic impedances for a designed 35-GHz GaAs mHEMT PA, it is shown that the application of harmonic tuning techniques is not only limited to low GHz frequencies. Then, in order to improve the efficiency of PAs for signals with large envelope variations, dynamic supply modulation (DSM) and dynamic load modulation (DLM) techniques are evaluated at transistor and PA levels using static measurements. The results show that the two techniques provide similar efficiencies down to a certain output power level. At further power back-off, their efficiencies start to differ due to their different technology-related intrinsic loss mechanisms. Finally, the feasibility of varactor-based DLM PA architectures for high-power (>1 W), high-frequency (>0.9 GHz) applications is shown for the first time. The technique is demonstrated by a modular approach whereby a varactor-based tunable matching network (VMN) is designed for and connected to an existing PA. An average power-added efficiency (PAEavg) of 53% at 6 W peak output power is achieved at 1 GHz using a 3.84-MHz WCDMA signal with 7 dB peak-to-average ratio. Then, in order to achieve a more wideband performance, an integrated approach is proposed in which the PA and VMN are co-designed. A PAEavg of 44% at 5 W peak power is achieved at 2.65 GHz for the same WCDMA signal but with 38.4 MHz bandwidth. This is the largest high-efficiency bandwidth reported for all efficiency enhancement techniques. Two digital predistortion techniques have also been proposed, by which normalized mean square errors of <-35 dB and adjacent channel leakage ratios of <-43 dBc were achieved in all the experiments.

load modulation

LDMOS

supply modulation

GaN HEMT

Power amplifier

wireless communications.

GaAs mHEMT

efficiency

Kollektorn, Kemivägen 9, MC2, Campus Johanneberg, Chalmers University of Technology
Opponent: Professor Amir Mortazawi from University of Michigan, Ann Arbor, USA.

Författare

Hossein Mashad Nemati

GigaHertz Centrum

Chalmers, Mikroteknologi och nanovetenskap (MC2), Mikrovågselektronik

High-Efficiency LDMOS Power-Amplifier Design at 1 GHz Using an Optimized Transistor Model

IEEE Transactions on Microwave Theory and Techniques,; Vol. 57(2009)p. 1647-1654

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Design of Varactor-Based Tunable Matching Networks for Dynamic Load Modulation of High Power Amplifiers

IEEE Transactions on Microwave Theory and Techniques,; Vol. 57(2009)p. 1110-1118

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Linearization of Efficiency-Optimized Dynamic Load Modulation Transmitter Architectures

IEEE Transactions on Microwave Theory and Techniques,; Vol. 58(2010)p. 873-881

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Design of High Efficiency Ka-Band Harmonically Tuned Power Amplifiers

2009 IEEE Radio and Wireless Symposium, RWS 2009; San Diego, CA; United States; 18 January 2008 through 22 January 2008,; (2009)p. 264-267

Paper i proceeding

Evaluation of a GaN HEMT transistor for load- and supply-modulation applications using intrinsic waveform measurements

IEEE MTT-S International Microwave Symposium Digest,; (2010)p. 509-512

Paper i proceeding

An efficiency optimized controlling scheme for dynamic load modulation of power amplifiers

European Microwave Conf., Proc., Oct. 2008,; (2008)p. 583-586

Paper i proceeding

Design of Highly Efficient Load Modulation Transmitter for Wideband Cellular Applications

IEEE Transactions on Microwave Theory and Techniques,; Vol. 58(2010)p. 2820-2828

Artikel i vetenskaplig tidskrift

Characterization of Switch Mode LDMOS and GaN Power Amplifiers for Optimal Use in Polar Transmitter Architectures

Proc. IEEE International Microwave Symposium,; (2008)p. 1505 - 1508

Paper i proceeding

High Efficiency LDMOS Current Mode Class-D Power amplifier at 1 GHz

36th European Microwave Conference,; Vol. 1(2006)p. 176-9

Paper i proceeding

Ämneskategorier

Elektroteknik och elektronik

Annan elektroteknik och elektronik

ISBN

978-91-7385-466-5

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 3147

Kollektorn, Kemivägen 9, MC2, Campus Johanneberg, Chalmers University of Technology

Opponent: Professor Amir Mortazawi from University of Michigan, Ann Arbor, USA.