Differential Power Amplifier Layout for Odd Harmonic Attenuation
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Solution Overview
Problem
Existing power amplifier circuits in mobile units suffer from reduced efficiency due to the output of unnecessary signals, particularly odd harmonics, which disrupt ideal operating conditions and reduce power efficiency, especially when operating in class E mode.
Innovation Solution
A power amplifier circuit utilizing a differential amplifier configuration with specific termination circuits and transmission lines to attenuate odd harmonics, including a first termination circuit with a lower capacitance capacitor and a second termination circuit with a capacitor and inductor, effectively reducing the output of odd harmonics by creating impedance mismatches and reflections, thereby improving efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If class E operation is used to increase efficiency, then power efficiency is improved, but odd harmonics are not properly attenuated resulting in unnecessary signal output
Solution Approach 1:
A third harmonic termination circuit is introduced as an intermediary component between the amplifier and the output. This termination circuit specifically targets and attenuates odd harmonics (particularly third harmonics) by providing a controlled impedance path, allowing the amplifier to operate in class E mode for high efficiency while preventing harmful harmonic signals from being output.
Solution Approach 2:
The termination circuit is designed with specific impedance parameters optimized for third harmonic frequencies. By carefully selecting the impedance value of the termination circuit, the amplifier can maintain class E operating conditions (which require specific impedance characteristics) while the termination circuit presents appropriate impedance to attenuate odd harmonics effectively.
2Object-generated harmful factors
If third harmonic impedance is not set to open-circuit impedance, then class E operation condition is not ideal, but odd harmonics can be attenuated
Solution Approach 1:
The termination circuit uses specifically designed impedance parameters that differ from traditional open-circuit requirements. By optimizing the impedance value of the termination circuit, the system achieves effective third harmonic attenuation while maintaining stable class E operation, demonstrating that ideal class E operation does not strictly require open-circuit impedance at third harmonic frequencies.
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 proposed solution significantly reduces the output of odd harmonics, enhancing the power amplifier circuit's efficiency by ensuring that the ratio of odd harmonics to the fundamental signal is lower in the output, thus improving the operating conditions and power efficiency, especially when operating in class E mode.
Implementation Method 1
effectively reducing the output of odd harmonics by creating impedance mismatches and reflections
Implementation Method 2
a first transmission line having one end connected to the first output terminal of the first amplifier; a second transmission line having one end connected to the second output terminal of the second amplifier
Implementation Method 3
a power combiner connected to the other end of the first transmission line and the other end of the second transmission line and configured to output an output signal obtained by combining the first amplified signal and the second amplified signal
Data Source
AI summary
A power amplifier circuit includes a power splitter, a first amplifier configured to output a first amplified signal from a first output terminal, and a second amplifier configured to output a second amplified signal from a second output terminal. The power amplifier circuit further includes a first termination circuit connected between the first output terminal and the second output terminal, a first transmission line, a second transmission line, a second termination circuit connected between another end of the first transmission line and another end of the second transmission line, and a power combiner.