Power Amplifier Matching Network for Independent Harmonic Impedance

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Solution Overview

Problem

Designing an impedance matching stage for power amplifiers is complicated due to the correlation between impedances at the fundamental frequency and higher harmonic frequencies, making it challenging to optimize impedance levels at both frequencies simultaneously, especially at the second harmonic frequency.

Innovation Solution

The impedance matching stage comprises a short-circuited stub and an open-circuited stub, along with a series branch, configured to set the input impedance at the fundamental frequency based on the load impedance and independently set the impedance at the second harmonic frequency, using transmission lines with specific characteristic impedances and electrical lengths to transform impedances without affecting the fundamental frequency impedance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If an impedance matching stage is optimized for a given impedance at the fundamental frequency, then the impedance at the fundamental frequency is improved, but the impedance levels at the second and higher harmonic frequencies are affected as well

Engineering Contradiction:

Improveimpedance matching precisionVSAvoidimpedance control flexibility

Core Design Contradiction:

Manufacturing precisionVSAdaptability or versatility

Solution Approach 1:

The impedance matching stage is segmented into functionally independent sub-networks: one dedicated to fundamental frequency impedance matching and another dedicated to harmonic frequency impedance control. This segmentation allows each sub-network to be optimized independently for its specific frequency range without compromising the other, resolving the contradiction between matching precision and control flexibility.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

An intermediary network is introduced between the fundamental frequency matching section and the harmonic frequency control section. This intermediary enables independent adjustment of harmonic impedances while maintaining the fundamental frequency match, acting as a mediator that decouples the interdependent impedance controls and provides the needed flexibility.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Device complexity

If the impedance matching stage uses conventional topology, then the design is simpler, but it is complicated to design for given impedances at both fundamental and harmonic frequencies simultaneously

Engineering Contradiction:

Improvecircuit topology complexityVSAvoiddesign ease

Core Design Contradiction:

Device complexityVSEase of manufacture

Solution Approach 1:

The conventional impedance matching stage is segmented into distinct functional blocks: a fundamental frequency matching network and a harmonic frequency control network. Each block can be designed and analyzed independently using standard techniques, making the overall design process easier despite the increased functional complexity. The segmentation allows designers to apply proven design methodologies to each segment separately.

Inventive Principle:

Principle #1Segmentation

3Reliability

If the impedance at the second harmonic frequency is optimized, then the voltage and current waveforms are improved for zero voltage switching, but the impedance at the fundamental frequency is affected

Engineering Contradiction:

Improvezero voltage switching performanceVSAvoidfundamental frequency impedance match

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration allows for independent design of suitable impedances at both the fundamental and second harmonic frequencies, ensuring proper input impedance at the fundamental frequency while maintaining a high impedance at the second harmonic frequency, thereby enhancing power amplifier efficiency and gain.

Implementation Method 1

The short-circuited stub is configured to present an input impedance at a second harmonic frequency that substantially equals a second desired impedance

Methodology Applied

Scientific EffectTransmission line impedance transformation:

Implementation Method 2

The open-circuited stub and the series branch are configured to set an input impedance of the impedance matching stage at a fundamental frequency in dependence of a load impedance

Methodology Applied

Scientific EffectTransmission line impedance transformation:

Data Source

PatentUS20250007470A1Power amplifier

Publication Date: 2025.01.02 AMPLEON NETHERLANDS

AI summary

The present invention relates to a power amplifier. The present invention particularly relates to switched-mode power amplifiers operable in a frequency range between 0.5 GHz and 40 GHz, and configured for outputting powers ranging from 1 W to 1 kW. The present invention further relates to an impedance matching stage to be used in such power amplifier. The impedance matching stage of the present invention comprises a short-circuited stub at its input, an open-circuited stub at its output, and a series branch connecting the input and output. By choosing suitable characteristic impedances and electrical lengths of the stubs and the series branch it becomes possible to independently choose the impedance to be presented to the power transistor at the fundamental and second harmonic frequencies.