Power Amplifier Harmonic Tuning Using FET Parasitic Capacitance
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Solution Overview
Problem
The characteristics of harmonic termination circuits in power amplifier modules deteriorate due to variations in elements, particularly with the reduction in substrate size and increase in RF signal frequencies, making it difficult to adjust the circuit characteristics effectively.
Innovation Solution
Incorporating a field effect transistor (FET) in the harmonic termination circuit and a control circuit that adjusts the gate voltage of the FET to control the parasitic capacitance, allowing for dynamic adjustment of the resonance frequency to mitigate these variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the sizes of elements such as inductors and capacitors are determined in advance, then the manufacturing process is simplified, but it becomes difficult to adjust the characteristics of the harmonic termination circuit in accordance with element variations
Solution Approach 1:
The patent introduces a varactor diode to replace fixed capacitors in the harmonic termination circuit, enabling dynamic adjustment of capacitance values. This allows the resonance frequency to be tuned according to element variations, resolving the contradiction between simplified manufacturing and adjustability by making the circuit characteristics dynamically adaptable rather than fixed during manufacturing
Solution Approach 2:
The patent changes the electrical parameters of the circuit by introducing variable capacitance through varactor diodes. By controlling the capacitance values of the varactor diodes, the resonance frequency of the harmonic termination circuit can be adjusted to compensate for element variations, thereby maintaining circuit performance without requiring complex manufacturing processes
2Volume of moving object
If the substrate size is reduced and RF signal frequency is increased, then the profile of the power amplifier module is improved, but the characteristics of the harmonic termination circuit deteriorate due to element variations
Solution Approach 1:
The patent employs varactor diodes with controllable capacitance to dynamically adjust the resonance frequency of the harmonic termination circuit. This dynamic adjustment capability compensates for the deteriorating characteristics caused by miniaturization and high-frequency operation, maintaining reliability while achieving compact size and high-frequency performance
Solution Approach 2:
The patent implements a control circuit that monitors the performance of the harmonic termination circuit and adjusts the capacitance of varactor diodes accordingly. This feedback mechanism ensures that the resonance frequency remains optimized despite element variations introduced by substrate miniaturization and high-frequency operation, thereby maintaining circuit reliability
3Device complexity
If fixed-size elements are used in the harmonic termination circuit, then the device complexity is reduced, but the resonance frequency cannot be adjusted to compensate for element variations
Solution Approach 1:
The patent replaces fixed capacitors with varactor diodes that provide variable capacitance, enabling dynamic tuning of the resonance frequency. This increases device complexity slightly but significantly improves manufacturing precision by allowing post-manufacturing adjustment of the resonance frequency to compensate for element variations
Solution Approach 2:
The patent changes the capacitance parameter of the harmonic termination circuit from fixed to variable by using varactor diodes. This allows the resonance frequency to be precisely adjusted after manufacturing to compensate for element variations, achieving high manufacturing precision while maintaining relatively simple circuit structure
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 enables the power amplifier module to maintain consistent performance by correcting the resonance frequency of the harmonic termination circuit, thereby mitigating the deterioration of its characteristics even with elemental variations, ensuring effective signal attenuation across a range of frequencies.
Implementation Method 1
a control circuit that controls a gate voltage of the at least one FET to adjust a capacitance value of a parasitic capacitance of the at least one FET
Implementation Method 2
a harmonic termination circuit that is disposed subsequent to the amplifier and that attenuates a harmonic component of the amplified signal
Data Source
AI summary
A power amplifier module includes an amplifier that amplifies an input signal and outputs the amplified signal, a harmonic termination circuit that is disposed subsequent to the amplifier and that attenuates a harmonic component of the amplified signal, the harmonic termination circuit including at least one field effect transistor (FET), and a control circuit that controls a gate voltage of the at least one FET to adjust a capacitance value of a parasitic capacitance of the at least one FET. The control circuit adjusts the capacitance value of the parasitic capacitance of the at least one FET, and thereby a resonance frequency of the harmonic termination circuit is adjusted.