Millimeter-Wave Harmonically-Tuned Silicon

Power Amplifiers for High Efficiency

Seyed Yahya Mortazavi

Dissertation submitted to the Faculty of

Virginia Polytechnic Institute and State University

in partial fulfillment of the requirements for the degree of

Doctor of Philosophy

in

Computer Engineering

Kwang-Jin Koh, Chair

Dong. S. Ha

Sanjay Raman

R. Michael Buehrer

Vinh Nguyen

June 23, 2016

Blacksburg, Virginia

Keywords: Harmonic Tuned Power Amplifier (PA), Inverse Class-F Power

Amplifier (PA), Millimeter Wave (mm-Wave), Power Amplifier (PA)

Copyright @ 2016, Seyed Yahya Mortazavi

Millimeter-Wave Harmonically-Tuned Silicon

Power Amplifiers for High Efficiency

Seyed Yahya Mortazavi

ABSTRACT

This research utilizes the Class F-1 harmonic tuning approach to improve the power efficiency and

power added efficiency (PAE) of the silicon power amplifiers (PAs) at mm-wave frequency bands.

This work tunes the 2nd and 3rd harmonic componets of voltage and current waveform over active

device to improve the efficiency of the PA. The potentials and limitations of the class-F-1 technique

in achieving a high PAE at microwave and higher frequencies, especially for integrated PAs based

on silicon process have been analyzed. To demonstrate effectiveness of the Class-F-1 approach a

multi-resonance 6th order load network is proposed which achieves 50% power added efficiency

with 18dBm output power at 24GHz. By optimizing this network for 38GHz, based on the loss of

passive components, PAE of 38.5% achieved. The design methodology developed for this network

and extensive small signal, large signal, and linearity performance of both PAs presented. To

further improve power efficiency of Class F-1 PAs, coupled inductor based harmonic tuning load

network proposed. The load network, utilizes coupled inductors to enhance quality factor of the

inductors and make wide bandwidth high impedance at 2nd harmonic and very low impedance at

3rd harmonic, which improves both efficiency and efficiency bandwidth. By using this load

network and optimizing for 28GHz, 2-stage PA implemented with PAE~42% with 16.5dBm

output power. As frequency increases to >30 GHz, the complexity of load network degrades the

power efficiency improvement of the Class-F-1 PAs. A simple /4 transformer based load network

proposed to tackle this issue and achieve high power efficiency. Using this load network, PAs

implemented with exceptional PAE performance of 43% at 41 GHz and 23% 94 GHz with output

power of 18 dBm and 11 dBm, respectively. To increase peak PAE bandwidth of PA, a simple

LC-based multi-resonance network proposed which provides in band mode transition from

Continuous-Class-F-1 to Continuous-Class-F. The PA operated at Continuous-Class-F-1 mode at

low signal frequency band and Continuous-Class-F mode at high signal frequency band. By using

mode-transition, PAE > 36.5% achieved over 25% fractional bandwidth (25 GHz~31 GHz).

In summary, this research presents different harmonic tuning load networks for Class F-1 operation

to address different issues and improve efficiency of mm-wave silicon PAs.

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To my dear parents and my lovely wife Shirin

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Attribution

This dissertation is composed of an introduction, five main chapters and a conclusion. The

main chapters are published in four conference papers and and either have or will be submitted to

archival journals for separate publication. Chapter three is published in a journal paper.

Dr. Kwang-Jin Koh, Ph.D., Assistant Professor in department of Electrical and computer

Engineering (ECE), Virginia Tech, Served as the committee chair and provided advice on the

works presented in each chapter. Dr. Koh is a coauthor on each and all of the papers.

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Table of Content

1 INTRODUCTION ................................................................................................................... 1

MOTIVATION ............................................................................................................................................. 1

PROBLEM STATEMENT ................................................................................................................................. 4

CONTRIBUTIONS OF THIS RESEARCH AND ORGANIZATION OF THE DISSERTATION ...................................................... 5

2 TECHNICAL BACKGROUND ................................................................................................... 8

THE MERITS FOR MEASURING EFFICIENCY PERFORMANCE OF PAS ......................................................................... 8

CLASSES OF PAS ....................................................................................................................................... 10

2.2.1 Linear power amplifiers (Class A/AB/ B) ..................................................................................... 10

2.2.2 Switching power amplifiers (Class D/E) ...................................................................................... 12

HARMONIC TUNED POWER AMPLIFIERS: CLASS F-1/CLASS F .............................................................................. 13

MM-WAVE SILICON POWER AMPLIFIERS ....................................................................................................... 14

HARMONIC TUNING PA AT MM-WAVE .......................................................................................................... 15

SUMMARY ............................................................................................................................................... 17

3 HIGH EFFICIENCY MM-WAVE CLASS F-1 PA WITH LC HARMONIC TUNING LOAD ................. 18

INTRODUCTION ......................................................................................................................................... 18

INVERSE CLASS-F POWER EFFICIENCY LIMITING FACTORS ................................................................................. 19

3.2.1 Finite Number of Harmonics Control .......................................................................................... 20

3.2.2 Finite Knee Voltage, Vknee ........................................................................................................... 21

3.2.3 Transistor Breakdown Voltage, VBK ............................................................................................ 22

3.2.4 Resistive Losses from Passive Load Network .............................................................................. 24

3.2.5 Other Non-Idealities ................................................................................................................... 25

INVERSE CLASS-F LOAD NETWORK ............................................................................................................... 26

3.3.1 Multi-Resonance Parallel Load ................................................................................................... 26

3.3.2 Dual-Resonance Series Load ....................................................................................................... 30

TWO-STAGE CLASS-F-1 POWER AMPLIFIER DESIGN ......................................................................................... 31

3.4.1 Inverse Class-F Output Power Amplifier ..................................................................................... 31

3.4.2 Class-AB Driving Amplifier .......................................................................................................... 35

3.4.3 Experimental Results .................................................................................................................. 37

SUMMARY ............................................................................................................................................... 42

4 HARMONIC LOAD MODULATORS FOR MM-WAVE CLASS-F-1 PA ......................................... 44

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INTRODUCTION ......................................................................................................................................... 44

MUTUAL IMPEDANCE MODULATION ............................................................................................................ 45

HIGH QUALITY-FACTOR COUPLED INDUCTORS DESIGN ..................................................................................... 48

COUPLED INDUCTORS BASED CLASS-F-1 LOAD ................................................................................................. 49

INVERSE CLASS-F POWER AMPLIFIER DESIGN ................................................................................................. 53

4.5.1 Inverse Class-F Output-Stage Amplifier ...................................................................................... 54

4.5.2 Class AB Driving Amplifier and Inter-Stage Matching ................................................................ 60

4.5.3 Experimental Results ................................................................................................................