Doherty Power Amplifier Matching Circuit for Wideband Efficiency
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Solution Overview
Problem
Conventional Doherty power amplifiers face trade-offs between high efficiency and high bandwidth, as well as size and complexity, making them impractical for Monolithic Microwave Integrated Circuits (MMIC) and Hybrid Integrated Circuits due to bulky harmonic termination networks and narrow bandwidth.
Innovation Solution
The use of a hybrid integrated matching circuit with an impedance inverting network and parasitic component integration to terminate harmonics, allowing for high efficiency and wide bandwidth without increasing size.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional switch mode Doherty power amplifiers use narrowband quarter wave transmission line for harmonic load terminations, then high back off efficiency is achieved, but bandwidth is limited
Solution Approach 1:
The patent changes the electrical length parameter of transmission lines from narrowband quarter-wave to wideband variable lengths. The main amplifier uses a transmission line with electrical length θ1 and the peaking amplifier uses a transmission line with electrical length θ2, where these lengths are optimized to provide both harmonic terminations and wideband impedance matching, resolving the contradiction between efficiency and bandwidth.
Solution Approach 2:
The transmission lines in the patent serve multiple functions simultaneously: they provide harmonic load terminations for efficiency while also serving as impedance matching networks for bandwidth. This multi-functionality eliminates the need for separate narrowband quarter-wave lines and bulky harmonic termination networks, achieving both high efficiency and wide bandwidth.
2Adaptability or versatility
If device parasitic compensation technique is used to expand bandwidth, then bandwidth is improved, but harmonic load terminations are not incorporated, reducing efficiency
Solution Approach 1:
The patent merges the bandwidth expansion function and harmonic termination function into a single integrated structure. The transmission lines are designed to simultaneously provide both functions: they compensate for device parasitics to expand bandwidth while also providing the necessary harmonic load terminations to maintain high efficiency, eliminating the trade-off between the two.
3Loss of energy
If harmonic matching network employing Switch Mode power amplifier topology is used, then high efficiency is achieved, but circuit size becomes bulky and complex
Solution Approach 1:
The transmission lines serve multiple functions: they provide harmonic terminations, impedance matching, and bandwidth expansion simultaneously. This eliminates the need for separate bulky harmonic termination networks and complex matching circuits, achieving high efficiency with a compact, integrated design suitable for MMIC applications.
Solution Approach 2:
The patent combines what were previously separate functions (harmonic termination network, impedance matching network, and bandwidth expansion circuit) into a single integrated transmission line structure. This merging dramatically reduces circuit size and complexity while maintaining high efficiency performance.
Data Source
AI summary
The present disclosure provides methods for manufacturing Doherty power amplifiers. The methods include: providing at least one main amplifier operated at a fundamental frequency; providing at least one peaking amplifier connected to the main amplifier in parallel and sharing a common load or a load; and connecting a first hybrid integrated matching circuit between output terminals of the at least one main amplifier and the at least one peaking amplifier. Connecting the first hybrid integrated matching circuit includes connecting a first circuit between the output terminals of the at least one main amplifier and the at least one peaking amplifier. The first circuit contributes as a part of an impedance inverting network of the first hybrid integrated matching circuit of the Doherty power amplifier.