Power Amplifier Harmonic Termination with Tunable FET 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 and combined impedance 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 variable capacitor that can dynamically adjust its capacitance value based on measured element variations. This dynamic adjustment capability allows the harmonic termination circuit to adapt to different element characteristics while maintaining standardized manufacturing processes for the fixed elements (inductors and base capacitor).
Solution Approach 2:
The patent implements a feedback mechanism where the actual characteristics of the elements are measured, and based on these measurements, the capacitance value is adjusted to compensate for variations. This closed-loop approach ensures that the circuit characteristics can be tuned to match design specifications despite element-to-element variations.
2Productivity
If the profile of substrates is reduced and RF signal frequencies are increased, then the power amplifier module achieves better integration and higher performance, but the characteristics of the harmonic termination circuit deteriorate due to element variations
Solution Approach 1:
The patent changes the parameter of capacitance from a fixed value to a variable value that can be adjusted based on measured element characteristics. This parameter change allows the circuit to compensate for the increased sensitivity to element variations that occurs at higher frequencies and smaller substrate sizes, thereby maintaining reliable harmonic termination performance.
3Device complexity
If fixed-size elements are used in the harmonic termination circuit, then the circuit structure is simplified, but the resonance frequency cannot be adjusted to compensate for element variations
Solution Approach 1:
The patent makes the capacitance parameter dynamic through the use of a variable capacitor, allowing the resonance frequency to be adjusted after manufacturing. This maintains the simplicity of the fixed element structure while adding the capability to precisely tune the resonance frequency to compensate for element variations.
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 stable signal attenuation across varying conditions, ensuring consistent performance even with elemental variations, by correcting the resonance frequency of the harmonic termination circuit.
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
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
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.