Power Amplifier Voltage Control for Harmonic Reduction at Back-Off
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Solution Overview
Problem
Current GSM power amplifiers exhibit poor harmonic performance, particularly during power back-off, leading to suboptimal call quality in complex spectrum environments with the coexistence of 2G, 3G, 4G, and 5G mobile communication technologies.
Innovation Solution
A power control apparatus comprising a voltage conversion circuit and a power control circuit that cooperatively reduce the DC voltage of a pre-stage power amplifier when the bias current of a final-stage power amplifier is small, thereby minimizing harmonic waves generated during power back-off, improving harmonic performance and call quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional power control is used in GSM power amplifiers, then the amplifier can operate across different power levels, but harmonic waves are generated during power back-off leading to poor harmonic performance
Solution Approach 1:
An intermediate control circuit is introduced between the power control voltage input and the power amplifier stages. This intermediate circuit processes the control voltage to generate optimized control signals for different amplifier stages, thereby reducing harmonic wave generation during power back-off while maintaining power level adaptability
Solution Approach 2:
Different control strategies are applied to different stages of the power amplifier. The control circuit provides stage-specific control voltages tailored to the characteristics of each amplifier stage, optimizing harmonic performance at each stage while maintaining overall power adaptability
2Power
If power back-off operation is performed to reduce output power, then lower transmission power is achieved, but harmonic performance deteriorates in complex spectrum environments
Solution Approach 1:
The control circuit dynamically adjusts control parameters based on the operating point and power back-off level. As the amplifier transitions between different power levels, the control circuit modifies control voltages in real-time to maintain optimal harmonic performance across the entire power range
Solution Approach 2:
Control voltage parameters are changed and optimized for different operating conditions. The intermediate control circuit transforms the input control voltage into stage-specific control parameters that are optimized to minimize harmonic generation at each power back-off level
3Device complexity
If simple power control circuitry is used, then device complexity is low, but harmonic performance is poor resulting in suboptimal call quality
Solution Approach 1:
The power control function is segmented into multiple independent control circuits, each responsible for a specific amplifier stage. This segmentation allows each sub-circuit to be relatively simple while the combined system achieves superior harmonic performance through coordinated stage control
Data Source
AI summary
A power control apparatus comprises a voltage conversion circuit and a power control circuit, wherein the voltage conversion circuit is used for converting a power control voltage and outputting a target control voltage; and the power control circuit is connected to the voltage conversion circuit and is used for performing power control on a received input signal according to the target control voltage, so as to obtain a target output signal. In this way, by means of the cooperation of a voltage conversion circuit and a power control circuit, a target control voltage performs power control on an input signal, such that the number of harmonic waves generated by a power amplifier during power back-off can be reduced, thereby improving the harmonic performance of the power amplifier.