Harmonic Termination Resonant Circuit for Low-Loss Power Amplifiers
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Solution Overview
Problem
Existing power amplifier circuits experience increased insertion loss due to varying on-resistance values of field effect transistors (FETs) in harmonic termination circuits, particularly when supporting multiple frequency bands, leading to attenuation of unwanted waves and reduced Q values.
Innovation Solution
A power amplifier circuit design incorporating a resonant circuit with a first inductance element, a capacitive element, and switches of common size and on-resistance values, controlled by a control circuit to adjust impedance and resonate at the frequency of the second-order harmonic wave, reducing insertion loss and enabling multi-band signal amplification.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If FETs of different element sizes are used in the harmonic termination circuit to compensate for parasitic capacitance variations, then the resonant frequency characteristics are improved, but the on-resistance values vary causing Q value reduction and increased insertion loss
Solution Approach 1:
The patent changes the operating parameters by adjusting the on-resistance values of switches through element size selection. By carefully choosing switch element sizes, the patent achieves both resonant frequency compensation and maintains low on-resistance to reduce insertion loss and maintain high Q values.
2Adaptability or versatility
If a FET with small element size is used for switching between resonant frequencies, then the resonant frequency can be switched, but the high on-resistance value lowers the Q value of the resonant circuit
Solution Approach 1:
The patent adjusts the element size parameter of the switching FET to optimize the balance between switching capability and Q value maintenance. By selecting appropriate element sizes, the patent enables resonant frequency switching while maintaining high Q values and low insertion loss.
3Ease of operation
If the Q value of the resonant circuit is reduced due to high on-resistance, then frequency switching is easier, but waves other than the harmonic wave are attenuated increasing insertion loss
Solution Approach 1:
The patent optimizes the on-resistance parameter of the switching FET by selecting appropriate element sizes. This allows the circuit to achieve both easy frequency switching and minimal signal attenuation by maintaining high Q values through low on-resistance switches.
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 effectively reduces insertion loss and enhances signal amplification across multiple frequency bands by maintaining consistent on-resistance values and adjusting impedance, thereby improving the Q value of the resonant circuit.
Implementation Method 1
a resonant circuit is used to attenuate a harmonic wave of an amplified signal output from an amplifier
Implementation Method 2
The resonant circuit includes a first inductance element disposed between the amplifier and a ground, a capacitive element disposed between the amplifier and the ground and connected in series to the first inductance element
Data Source
AI summary
A power amplifier circuit includes: an amplifier that amplifies an input signal; and a resonant circuit that is connected to an output terminal of the amplifier and that attenuates a harmonic wave of an amplified signal obtained by amplifying the input signal. The resonant circuit includes an inductor disposed between the amplifier and a ground, a capacitive element disposed between the amplifier and the ground and connected in series to the inductor, an inductor connected in parallel to the inductor, a switch connected in series to the inductor, and a switch that is connected in parallel to the switch and that is of an element size common to an element size of the switch.