Input Fractional Harmonic Resonators for Broadband RF Amplifiers
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Solution Overview
Problem
Designing broadband power amplifiers, particularly those using GaN-based devices, faces challenges in achieving high efficiency and linearity due to nonlinear input capacitance generating harmonics and intermodulation distortion, and the impact of source second harmonic impedance on drain efficiency, making it difficult to achieve concurrent multi-band, broadband operation with good performance.
Innovation Solution
The implementation of an input-side impedance matching circuit with a single-section T-match or multiple-section bandpass topology, combined with a fractional harmonic resonator circuit that resonates between the fundamental and second harmonic frequencies, to control second harmonic impedance and emulate a low impedance condition, thereby enhancing efficiency and linearity across a wide fractional bandwidth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If broadband operation is implemented in power amplifiers, then frequency range is extended, but harmonic distortion and intermodulation increase
Solution Approach 1:
The patent extracts and separately manages harmonic frequencies by implementing input-side fractional harmonic resonator circuits that specifically target and control second harmonic impedance. This separates the handling of fundamental frequencies and harmonic frequencies into distinct circuit paths, allowing broadband operation while controlling harmonic distortion through dedicated resonator circuits.
Solution Approach 2:
The patent introduces fractional harmonic resonator circuits as intermediary elements between the input signal and the amplifier device. These resonators act as mediators that control second harmonic impedance and prevent harmonic interactions from degrading performance, enabling broadband operation without the harmful effects of uncontrolled harmonic distortion.
2Manufacturing precision
If input impedance matching is optimized for fundamental frequency, then linearity improves, but harmonic control deteriorates
Solution Approach 1:
The patent segments the impedance matching function into separate circuits: one for fundamental frequency matching and another for harmonic control. The input impedance matching circuit handles fundamental frequency optimization while fractional harmonic resonator circuits independently manage second harmonic impedance, allowing both functions to be optimized without compromise.
Solution Approach 2:
The patent applies different impedance characteristics to different frequency regions. The input impedance matching circuit provides optimized matching for fundamental frequencies, while fractional harmonic resonators provide specific impedance control for second harmonic frequencies. This local optimization of impedance characteristics for different frequency bands enables simultaneous improvement of linearity and harmonic control.
3Loss of energy
If GaN-based devices are used, then power efficiency increases, but nonlinear input capacitance effects worsen
Solution Approach 1:
The patent converts the harmful effect of nonlinear input capacitance in GaN devices into a beneficial outcome by using the generated second harmonic signals to drive input-side fractional harmonic resonators. These resonators control the second harmonic impedance to improve efficiency, thereby converting what would normally be harmful harmonic distortion into a mechanism for enhancing power 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 approach allows for high efficiency and linearity in broadband applications by effectively managing harmonic interactions and impedance conditions, enabling GaN-based power amplifiers to achieve broadband operation with improved performance.
Implementation Method 1
a fractional harmonic resonator circuit that resonates between the fundamental and second harmonic frequencies, to control second harmonic impedance and emulate a low impedance condition
Data Source
AI summary
A radio frequency amplifier includes a transistor, an input impedance matching circuit (e.g., a single-section T-match circuit or a multiple-section bandpass circuit), and a fractional harmonic resonator circuit. The input impedance matching circuit is coupled between an amplification path input and a transistor input terminal. An input of the fractional harmonic resonator circuit is coupled to the amplification path input, and an output of fractional harmonic resonator circuit is coupled to the transistor input terminal. The fractional harmonic resonator circuit is configured to resonate at a resonant frequency that is between a fundamental frequency of operation of the RF amplifier and a second harmonic of the fundamental frequency. According to a further embodiment, the fractional harmonic resonator circuit resonates at a fraction, x, of the fundamental frequency, wherein the fraction is between about 1.25 and about 1.9 (e.g., x≈1.5).