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Doherty Power Amplifiers

From Fundamentals to Advanced Design Methods

  • 1st Edition - March 27, 2018
  • Latest edition
  • Author: Bumman Kim
  • Language: English

Doherty Power Amplifiers: From Fundamentals to Advanced Design Methods is a great resource for both RF and microwave engineers and graduate students who want to understan… Read more

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Description

Doherty Power Amplifiers: From Fundamentals to Advanced Design Methods is a great resource for both RF and microwave engineers and graduate students who want to understand and implement the technology into future base station and mobile handset systems. The book introduces the very basic operational principles of the Doherty Amplifier and its non-ideal behaviors. The different transconductance requirements for carrier and peaking amplifiers, reactive element effect, and knee voltage effect are described. In addition, several methods to correct imperfections are introduced, such as uneven input drive, gate bias adaptation, dual input drive and the offset line technique.

Advanced design methods of Doherty Amplifiers are also explained, including multistage/multiway Doherty power amplifiers which can enhance the efficiency of the amplification of a highly-modulated signal. Other covered topics include signal tracking operation which increases the dynamic range, highly efficient saturated amplifiers, and broadband amplifiers, amongst other comprehensive, related topics.

Key features

  • Specifically written on the Doherty Power Amplifier by the world’s leading expert, providing an in-depth presentation of principles and design techniques
  • Includes detailed analysis on correcting non-ideal behaviors of Doherty Power Amplifiers
  • Presents advanced Doherty Power Amplifier architectures

Readership

University and industry engineers in RF and microwave engineering, graduate students

Table of contents

I Introduction to Doherty Amplifier

    1. Historical Survey

    2. Basic Operation Principle

      1. Load Modulation Behavior

    1. Load Impedance Modulation

    2. Voltage, Current and Load Impedance Profiles

    3. Load Lines for the Modulated Loads

      1. Efficiency and Gain Characteristics

    1. Efficiency of Doherty Amplifier

    2. Gain of Doherty Amplifier

    1. Offset Line Technique

      1. Realization of Doherty Amplifier

      2. Operation of Offset Line

    1. Offset Line at Carrier Amplifier

    2. Offset Line at the Peaking Amplifier

    1. Other Load Modulation Methods

      1. Voltage Combined Doherty

    1. Series configured Doherty amplifier in voltage combining mode

    2. Transformer based Voltage Combined Doherty Amplifier

1.4.2 Inverted Load Modulation

      1. Direct Matching at the First Peak Efficiency Point

    1. Using Ropt/2 Inverter

    2. Using 2Ropt Inverter

Chapter II Realization of Proper Load Modulation using a Real Transistor

    1. Correction for Lower Transconductance of Peaking Amplifier

2.1.1. Uneven Drive through Coupler

a) Current Ratio of Peaking Versus Carrier Amplifiers

b) Efficiency of the Asymmetric Amplifier with Uneven Power Drive

2.1.2 Gate Bias Adaptation to Compensate the Low Current of Peaking Amplifier

a) Peaking Amplifier Adaptation

b) Adaptation of the Both Amplifiers

2.2 Knee Voltage Effect on Doherty Amplifier Operation

2.2.1 Doherty Amplifier Operation with Knee Voltage Effect

2.2.2. Load Modulation Behavior of Doherty Amplifier with Optimized Carrier Amplifier

2.3 Offset Line Design for Compensation of Peaking Amplifier Phase Variation

2.3.1 Phase variation of the peaking amplifier

      1. Load modulation of peaking amplifier with the additional offset lines

2.3.3 The load of the carrier amplifier with the additional offset lines

      1. Simulation Results with Real Device

      2. Measurement Results

      3. Conclusions

Chapter III Enhancement of Doherty Amplifier

3.1 Doherty amplifier with Asymmetric Vds

3.2 Quarter-wave Inverter Matched at the First Peak Efficiency Point

3.2.1 Analysis of the Doherty PA

3.2.2 Design Method and Simulation Result

3.3 Optimized Design of GaN HEMT Doherty Power Amplifier with High Gain and High PAE

3.3.1 Design of Carrier and Peaking PAs

3.3.2 Operation of Doherty PA

3.4 Optimized Peaking Amplifier design for Doherty Amplifier

      1. Optimized Design of Peaking Amplifier for Ideal Doherty Operation

      2. Simulation and Experimental Results

CH IV Advanced Architecture of Doherty Amplifier

    1. Multi-way Doherty Amplifier

      1. Load Modulation

      2. Efficiency of N-way Doherty Amplifier

      1. Linearity

4.2 3-stage Doherty Amplifier

4.2.1 Proper Impedance Transformation Ratio of Three-Stage Doherty Amplifiers

4.2.2 Load Modulation of the Three-Stage II Doherty Power Amplifier

4.2.3 Gate Bias Adaptation of the Peaking Power Amplifiers in Three-Stage Circuit

4.3 Conclusions

CH V Linear Doherty PA for Handset Application

5.1. Introduction

5.2. Design of Linear Doherty Power Amplifier

      1. load Modulation of Doherty Amplifier Based HBT

a) Gain modulation of carrier amplifier

b) Flat gain operation of the Doherty PA based on HBT

5.2.2. IMD3 cancellation with proper harmonic load conditions

5.3. Compact Design for Handset Application

5.3.1. Input Power Dividing Circuit

a) Input Dividing with Coupler

b) Direct Input Dividing without Coupler

c) Realization of the Input Circuit

5.3.2. Output Circuit Implementation

5.4. Implementation and Measurement

5.5. Doherty Amplifier Based on CMOS Process

5.5.1. Implementation of Linear CMOS Doherty PA

5.5.2. Measurement Results

    1. Average Power Tracking Operation of Doherty Amplifier

      1. Adaptive Base Bias Circuit for Average Power Tracking

      2. Implementation and Measurement

5.7. Conclusions

Product details

  • Edition: 1
  • Latest edition
  • Published: March 28, 2018
  • Language: English

About the author

BK

Bumman Kim

Bumman Kim (M'78–SM'97–F'07) received the Ph.D. degree in electrical engineering from Carnegie Mellon University, Pittsburgh, PA, in 1979. In 1981, he joined the Central Research Laboratories, Texas Instruments Incorporated, where he was involved in development of GaAs power field-effect transistors (FETs) and monolithic microwave integrated circuits (MMICs). He has developed a large-signal model of a power FET, dual-gate FETs for gain control, high-power distributed amplifiers, and various millimeter-wave MMICs. In 1989, he joined the Pohang University of Science and Technology (POSTECH), Pohang, Gyungbuk, Korea, where he is a POSTECH Fellow and a Namko Professor with the Department of Electrical Engineering, and Director of the Microwave Application Research Center. He is involved in device and circuit technology for RF integrated circuits (RFICs) and PAs. He has authored over 300 technical papers. Prof. Kim is a member of the Korean Academy of Science and Technology and the National Academy of Engineering of Korea. He was an associate editor for the IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES. He was a Distinguished Lecturer of the IEEE Microwave Theory and Techniques Society (IEEE MTT-S) and an IEEE MTT-S Administrative Committee (AdCom) member.
Affiliations and expertise
Pohang University of Science and Technology (POSTECH), Korea

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