RF Power Amplifier Harmonic Load Circuit for High PAE
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Solution Overview
Problem
High-power radio frequency power amplifiers face challenges in achieving high power added efficiency (PAE) due to the influence of parasitic capacitance and inductance, which are not adequately considered in existing designs, leading to inefficiencies even with high-power amplifying elements.
Innovation Solution
A radio frequency power amplifier design that includes a first and second resonant circuit connected to the output terminal, with specific resonance frequencies and impedance settings to adjust the phase of reflection coefficients at harmonics, effectively managing parasitic capacitance and inductance to meet class F or inverse class F load conditions, thereby enhancing PAE.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a class F load circuit is provided to short circuit even harmonics and open odd harmonics, then power added efficiency is improved, but parasitic capacitance between drain and source degrades the temporal waveforms and prevents high-efficiency operation
Solution Approach 1:
The patent changes the design parameters by introducing series inductors in the load circuit and adjusting the resonance frequencies of the harmonic control circuits. By modifying the circuit parameters (inductance values, resonance frequencies) to compensate for parasitic capacitance effects, the patent achieves proper class F load conditions despite the presence of parasitic elements, thereby resolving the contradiction between efficiency improvement and parasitic degradation
2Power
If high-power amplifying elements are used to increase output power, then power output is improved, but parasitic inductance and capacitance become more significant and reduce efficiency
Solution Approach 1:
The patent applies preliminary anti-action by pre-compensating for the harmful effects of parasitic inductance and capacitance through careful circuit design. The load circuit is designed with series inductors and tuned resonance frequencies that counteract the parasitic effects before they can degrade performance, allowing high-power operation to achieve both high output power and high efficiency simultaneously
3Device complexity
If existing load circuit designs are used without considering parasitic inductance, then device complexity is reduced, but power added efficiency cannot be achieved in high-power applications
Solution Approach 1:
The patent performs preliminary action by incorporating parasitic inductance and capacitance considerations into the design phase. The load circuit is designed with predetermined series inductors and resonance frequency settings that account for parasitic effects, so that when the amplifier operates at high power, the efficiency is already optimized rather than requiring complex post-design adjustments
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
The design achieves high PAE by ensuring the load conditions are met, even with high-power amplifying elements, by adjusting the phase of reflection coefficients at second and third harmonics, resulting in improved efficiency and output power.
Implementation Method 1
The first resonant circuit has a resonance frequency higher than a frequency of a second harmonic of the input signal, and the second resonant circuit has a resonance frequency lower than a frequency of a third harmonic of the input signal
Data Source
AI summary
A radio frequency power amplifier includes: an amplifying element which amplifies an input signal and outputs the signal from an output terminal; and an output load circuit which includes a first resonant circuit and a second resonant circuit that are connected to the output terminal. The first resonant circuit has a resonance frequency higher than the frequency of the second harmonic of the input signal, and the second resonant circuit has a resonance frequency lower than the frequency of the third harmonic of the input signal. The output load circuit has such an impedance looking from the output terminal that a phase of a reflection coefficient at the second harmonic of the input signal is greater than 180 degrees and less than 360 degrees, and a phase of a reflection coefficient at the third harmonic of the input signal is greater than 0 degrees and less than 180 degrees.