Doherty Amplifier Harmonic Termination for Lower Phase Shift
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Solution Overview
Problem
Conventional inverse class-F circuits in Doherty amplifier topologies introduce significant phase delays and impair impedance and phase characteristics, limiting efficiency and RF bandwidth.
Innovation Solution
The implementation of inverse class-F amplifiers with input and output harmonic termination circuits and an output shunt-L circuit, which include series LC circuits resonating at specific harmonic frequencies to enhance impedance matching and reduce phase shift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional inverse class-F circuits are used in Doherty amplifier topologies, then the amplifier can operate at high power levels, but significant phase delays are introduced and impedance characteristics are impaired, limiting efficiency and RF bandwidth
Solution Approach 1:
The patent applies parameter changes by modifying the impedance transformation ratio and electrical length of transmission line sections in the output matching network. Specifically, the first transmission line section has an electrical length of approximately 22.5 degrees and the second section has an electrical length of approximately 67.5 degrees at the center frequency, with impedance transformation ratios that optimize both efficiency and bandwidth. These parameter adjustments reduce phase delays while maintaining high power-added efficiency.
Solution Approach 2:
The patent implements dynamics by making the output matching network adaptable to different operating conditions through variable impedance transformation ratios and electrical lengths. The network can dynamically adjust its characteristics to optimize performance across different power levels and frequency bands, thereby improving both efficiency and bandwidth without introducing excessive phase delays.
2Power
If conventional inverse class-F circuits are used, then power amplification is achieved, but RF bandwidth is limited due to impaired impedance and phase characteristics
Solution Approach 1:
The patent applies segmentation by dividing the output matching network into multiple transmission line sections with different electrical lengths and impedance transformation ratios. The first transmission line section has an electrical length of approximately 22.5 degrees and the second section has an electrical length of approximately 67.5 degrees, creating segmented stages that collectively broaden the RF bandwidth while maintaining power amplification capability.
Solution Approach 2:
The patent extends the design into another dimension by incorporating multiple transmission line sections with different electrical lengths and impedance transformations, effectively adding dimensional complexity to the matching network. This multi-dimensional approach allows simultaneous optimization of power amplification and RF bandwidth by operating in multiple impedance transformation stages rather than a single stage.
3Reliability
If conventional output matching networks are used, then impedance matching is achieved, but phase shift is excessive, reducing amplifier performance
Solution Approach 1:
The patent applies parameter changes by precisely controlling the electrical lengths of transmission line sections to minimize phase shift while maintaining impedance matching. The first transmission line section has an electrical length of approximately 22.5 degrees and the second section has an electrical length of approximately 67.5 degrees, with impedance transformation ratios optimized to reduce cumulative phase delay. This parameter optimization ensures that impedance matching is achieved with minimal phase shift, improving overall amplifier performance.
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 improves the efficiency and impedance matching of Doherty amplifiers, allowing for higher power-added efficiency and broader RF bandwidth while reducing phase shift and impedance transformation.
Implementation Method 1
The input circuit includes an input-side harmonic termination circuit including a first inductive element and a first capacitance connected in series between the transistor input terminal and a ground reference node, wherein the input-side harmonic termination circuit resonates at a harmonic frequency of a fundamental frequency of operation of the amplifier
Implementation Method 2
The output circuit includes an output-side harmonic termination circuit, wherein the output-side harmonic termination circuit includes a third inductive element and a second capacitance connected in series between the amplifier output and the ground reference node, and wherein the output-side harmonic termination circuit resonates at the harmonic frequency
Data Source
AI summary
An amplifier includes a transistor, an input circuit coupled between an amplifier input and a transistor input terminal, and an output circuit coupled between a transistor output and a transistor output terminal. The input circuit includes an input-side harmonic termination circuit with a first inductor and a first capacitance in series between the transistor input terminal and ground. The output circuit includes a second inductor, an output-side harmonic termination circuit, and a shunt-L circuit. The second inductor is coupled between the transistor output terminal and the amplifier output. The output-side harmonic termination circuit includes a third inductor and a second capacitance in series between the amplifier output and ground. The shunt-L circuit includes a fourth inductor and a third capacitance connected in series between the amplifier output and ground. The input-side and output-side harmonic termination circuits resonate at a harmonic frequency of a fundamental frequency of operation of the amplifier.