High-Frequency Semiconductor Amplifier Harmonic Impedance Matching
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Solution Overview
Problem
High-frequency semiconductor amplifiers face challenges in achieving high power-added efficiency due to difficulties in effectively matching load impedances for fundamental, second harmonic, and third harmonic frequencies, which affects their operation in inverse class-F mode.
Innovation Solution
The design incorporates a specific output matching circuit comprising microstrip lines and a wire part, which transforms the load impedance at the fundamental frequency to a desired value and sets the load impedance at even harmonics to infinity and odd harmonics to zero, enabling inverse class-F operation by resonating the capacitive and inductive components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If conventional output matching circuits are used, then the amplifier can operate at high frequency, but the power-added efficiency is insufficient due to improper load impedance matching for harmonics
Solution Approach 1:
The output matching circuit is segmented into multiple transmission lines with different electrical lengths (first transmission line: 220 degrees, second transmission line: 110 degrees, third transmission line: 55 degrees at fundamental frequency) to independently control impedance at different harmonic frequencies. Each transmission line segment targets specific harmonic components (fundamental, second harmonic, third harmonic) to achieve inverse class-F operation.
Solution Approach 2:
Different portions of the output matching circuit are designed with different electrical lengths and impedance characteristics to create locally optimized conditions for specific frequency components. The first transmission line provides inductive reactance for fundamental frequency, while the second and third lines provide capacitive reactance for harmonic frequencies, creating localized impedance transformations throughout the circuit.
2Use of energy by moving object
If the output matching circuit uses multiple transmission lines with different electrical lengths, then harmonic impedance matching is improved, but the circuit area increases
Solution Approach 1:
The transmission lines are arranged in a nested configuration where the second transmission line is positioned within or adjacent to the first transmission line, and the third transmission line is positioned within or adjacent to the second. This nesting allows multiple impedance transformation functions to be achieved within a compact footprint, reducing the overall circuit area while maintaining the required electrical lengths for harmonic matching.
3Use of energy by moving object
If the amplifier operates in inverse class-F mode with proper harmonic matching, then power-added efficiency increases, but the device becomes more sensitive to manufacturing variations
Solution Approach 1:
The circuit is designed to operate at specific electrical length parameters (220 degrees, 110 degrees, 55 degrees at fundamental frequency) that create a favorable impedance transformation ratio. These parameter choices provide optimized sensitivity characteristics where the impedance transformation is less affected by small manufacturing variations, improving robustness while maintaining high power-added efficiency.
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 achieves high power-added efficiency by eliminating even harmonics of voltage and odd harmonics of current, with improved power-added efficiency by approximately 5-10% and reduced unnecessary radiation due to optimized microstrip line dimensions.
Implementation Method 1
a first microstrip line... transforms a load impedance at a fundamental frequency to a desired load impedance
Implementation Method 2
a wire part... having a resonance frequency which is substantially equal to a third harmonic frequency of the fundamental frequency... the load impedance at the third harmonic frequency is zero
Implementation Method 3
a parallel resonance circuit coupled to a wiring which spans from the impedance transformer to the amplifying device... having a resonance frequency which is substantially equal to a second harmonic frequency
Data Source
Figure 1A~1B
Figure 2
Figure 3A~3B
AI summary
According to one embodiment, a high-frequency semiconductor amplifier (1) includes an input terminal (10), an input matching circuit (12), a high-frequency semiconductor amplifying element (14), an output matching circuit (21) and an output terminal (18). The input terminal (10) is inputted with a fundamental signal. The fundamental signal has a first frequency band and a first center frequency in the first frequency band. The input matching circuit (12) includes an input end and an output end. The input end of the input matching circuit (12) is connected to the input terminal (10). The high-frequency semiconductor amplifying element (14) includes an input end and an output end. The input end of the high-frequency semiconductor amplifying element (14) is connected to the output end of the input matching circuit (12). The high-frequency semiconductor amplifying element (14) is configured to amplify the fundamental signal.