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High Efficiency Microwave Amplifiers and SiC Varactors Optimized for Dynamic Load Modulation

Christer Andersson (Institutionen för mikroteknologi och nanovetenskap, Mikrovågselektronik ; GigaHertz Centrum)
Göteborg : Chalmers University of Technology, 2013. ISBN: 978-91-7385-830-4.- 82 s.

The increasing use of mobile networks as the main source of internet connectivity is creating challenges in the infrastructure. Customer demand is a moving target and continuous hardware developments are necessary to supply higher data rates in an environmentally sustainable and cost effective way. This thesis reviews and advances the status of realizing wideband and high efficiency power amplifiers, which will facilitate improvements in network capacity and energy efficiency. Several demonstrator PAs are proposed, analyzed, designed, and characterized: First, resistive loading at higher harmonics in wideband power amplifier design suitable for envelope tracking (ET) is proposed. A 40 dBm decade bandwidth 0.4–4.1 GHz PA is designed, with 10–15 dB gain and 40–62% drain efficiency. Its versatility is demonstrated by digital pre-distortion (DPD) linearized measurements resulting in adjacent channel leakage ratios (ACLR) lower than −46 dBc for various downlink signals (WCDMA, LTE, WiMAX). Second, a theory for class-J microwave frequency dynamic load modulation (DLM) PAs is derived. This connects transistor technology and load network requirements to enable power-scalable and bandwidth conscious designs. A 38 dBm PA is designed at 2.08 GHz, maintaining efficiencies >45% over 8 dB of output power back-off (OPBO) dynamic range. From this pre-study a fully packaged 86-W peak power version at 2.14 GHz is designed. ACLR after DPD is −46 dBc at a drain efficiency of 34%. For DLM PAs there is a need for varactors with large effective tuning range and high breakdown voltage. For this purpose, SiC Schottky diode varactors are developed with an effective tuning range of 6:1 and supporting a 3:1 tuning ratio at 36 V of RF swing. Nonlinear characterization to enable Q-factor extraction in the presence of distortion is proposed and demonstrated by multi-harmonic active source- and load-pull, offering insights to tunable network design. Third, a method to evaluate and optimize dual-RF input PAs, while catering to higher harmonic conditions and transistor parasitics, is proposed. The method is validated by a PA design having a peak power of 44 +/- 0.9 dBm and 6 dB OPBO PAE exceeding 45% over a 1–3 GHz bandwidth. The results in this thesis contribute with a novel device and analysis of high efficiency and wideband PAs, aiding in the design of key components for future energy efficient and high capacity wireless systems.

Nyckelord: GaN, energy efficiency, HEMT, load modulation, nonlinear measurements, power amplifiers, SiC, varactors, wide bandgap technology

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Denna post skapades 2013-04-24. Senast ändrad 2013-09-25.
CPL Pubid: 176098


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Institutioner (Chalmers)

Institutionen för mikroteknologi och nanovetenskap, Mikrovågselektronik
GigaHertz Centrum


Informations- och kommunikationsteknik
Hållbar utveckling
Elektroteknik och elektronik

Chalmers infrastruktur

C3SE/SNIC (Chalmers Centre for Computational Science and Engineering)
NFL/Myfab (Nanofabrication Laboratory)

Relaterade publikationer

Inkluderade delarbeten:

A SiC Varactor With Large Effective Tuning Range for Microwave Power Applications

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

Nonlinear Characterization of Varactors for Tunable Networks by Active Source-Pull and Load-Pull

High-Efficiency RF Pulsewidth Modulation of Class-E Power Amplifiers

A double stub impedance tuner with SiC diode varactors

Epitaxial and Layout Optimization of SiC Microwave Power Varactors

SiC Varactors for Dynamic Load Modulation of Microwave Power Amplifiers

Decade bandwidth high efficiency GaN HEMT power amplifier designed with resistive harmonic loading

A novel wideband and reconfigurable high average efficiency power amplifier

Linearization Study of a Highly Efficient CMOS-GaN RF Pulse Width Modulation Based Transmitter

Design and characterization of SiC varactor-based phase shifters

Theory and Design of Class-J Power Amplifiers With Dynamic Load Modulation

A Modified Doherty Power Amplifier With Extended Bandwidth and Reconfigurable Efficiency


Datum: 2013-05-23
Tid: 10:00
Lokal: Kollektorn, MC2, Kemivägen 9, Chalmers University of Technology
Opponent: L. C. N. de Vreede

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Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie 3511

Technical report MC2 - Department of Microtechnology and Nanoscience, Chalmers University of Technology 243