RF Power Amplifiers, Classes A-S:
How the Circuits Operate, How to Design Them, and When to Use Each

There are at least 10 classes of RF Power Amplifiers, and several combinations of these classes. This 2-day course provides a detailed explanation of the various classes of RF Power Amplifiers, and where each class is used in today's wireless designs. Amplifier Classes A through S are defined and clearly explained, including the advantages, disadvantages, applications, and circuit topologies for each Class. If you are involved in using or designing RF Power Amplifiers for today's wireless designs, then this course will help you use the right Class of RF Power Amplifier for the right application.

Instructor: Nathan O. Sokal

• RF Power Amplifiers - Overview
  • Physical Realizations
    • Monolithic vs Discrete Assembly
  • Classes vs. Transistor operating modes
  • Applications
  • Efficiency
    • Definitions & Equations
    • Transistor Limits
  • Transistor Utilization Factor
• Description of Amplifier Classes
  • Linear Amplifiers - Classes A, AB, B, C, F1
    • Class A, AB, B - Circuit Operation Definitions
      • Single Ended, Push-Pull
      • Input/Output Transfer Functions
      • Bias Points; Biasing for Minimum Distortion
    • Class C Amplifier
      • Efficiency vs. Power, Vcc, Bandwidth
    • Class F1 Amplifier
    • Stability - Linear Amplifiers
  • Switching Mode Amplifiers - Classes D, E, F2, F3, S
    • Benefits vs Linear
    • Principles for High Efficiency
    • Design Difficulties
    • Advantages with examples
    • Disadvantages
    • Class D vs Class E Amplifiers
    • Class S Amplifier - Description
  • Discussion Topics
    • Switching (Class E) vs. Linear (Class B & C)
    • Experimental Results - Class E
    • Class E Applications by Modulation Type
    • Advantages & Disadvantages - Class D vs Class E
    • Mixed Mode Amplifiers
• System Level Topics
  • Predistortion of Input Signal
  • Feed-Forward Power Amplifier
  • Envelope Elimination and Restoration (EER)
  • Linear Amplification with Nonlinear Components (LINC)
  • Amplitude Control or Modulation
  • Choice of Power Amplifier Type
• Switching Mode Power Amplifier Circuit Design Methods
  • Analytic, Numerical, Programs
  • Circuit Computer Aided Design (CAD) Considerations
  • CAD Examples - Classes D & E
    • Real Circuit Complications
    • Evaluation, Simulation, & Measurement Comparisons
  • Impedance Matching Networks
  • Hands-On Exercise
    • Design and Optimize a Class E or D Power Amplifier
• References

A comprehensive set of seminar notes is provided.

Beginner through advanced design egineers and their supervisors, who are concerned with designing any type of RF power amplifier product, e.g., cell-phone handset, wireless device, radio transmitter, or RF-power source for induction or dielectric heating, plasma generation, or illumination.

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Nathan Sokal was awarded the 2007 Microwave Pioneer Award of the IEEE Microwave Theory and Techniques Society (MTT-S) "in recognition of a major, lasting, contribution... at least twenty years prior to the year of the award... for development of the Class-E RF power amplifier." He was elected a Fellow of the IEEE in 1989, for contributions to the technology of high-efficiency power conversion and RF power amplification. In 1965, he founded Design Automation, Inc., a consulting company doing electronics design review, product design, and solving "unsolvable" problems, for equipment-manufacturing clients. Much of that work has been on high-efficiency switching-mode RF power amplifiers at frequencies up to 2.5 GHz, and in switching-mode DC/DC power conversion. He holds eight patents in power electronics, and is the author of one book and more than a hundred technical papers, mostly in high-efficiency generation of RF power and DC power. During 1950-1965 Nathan held engineering and supervisory positions for design, manufacture, and applications of analog and digital equipment. He received B.S. and M.S. degrees in Electrical Engineering from M.I.T. in 1950. Nathan is a Technical Advisor to the American Radio Relay League, on RF power amplifiers and DC power supplies, and a member of the Electromagnetics Society, Eta Kappa Nu, and Sigma Xi honorary professional societies.