Doherty Amplifier Amplitude-Phase Control for Distortion Drift
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Solution Overview
Problem
Existing distortion compensating circuits fail to effectively reduce distortion in amplifier output signals when the non-linear characteristic of the amplifier changes due to factors like temperature or deterioration over time, as they rely on fixed compensation coefficients that do not adapt to these changes.
Innovation Solution
An amplitude and phase control device that divides a transmission signal into two signals, applies distortion compensation, and adjusts amplitude and phase based on error calculations to maintain effective distortion reduction even when the non-linear characteristic of the Doherty amplifier changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed compensation coefficients are used in the distortion compensating circuit, then the circuit structure remains simple, but the distortion reduction effectiveness deteriorates when the amplifier's non-linear characteristic changes
Solution Approach 1:
The patent implements dynamic adjustment of compensation coefficients by dividing the signal into multiple bands and independently controlling the amplitude and phase for each band. This allows the compensation characteristics to adapt to changes in the amplifier's non-linear behavior while maintaining a relatively simple overall circuit structure.
Solution Approach 2:
The patent changes the parameters (amplitude and phase) of the compensation signal based on the detected error between the actual output and the ideal output. By dynamically adjusting these parameters according to the amplifier's actual state, the system maintains effective distortion compensation even when characteristics drift over time or with temperature changes.
2Productivity
If the number of compensation coefficients is fixed, then the calculation complexity remains low, but the adaptability to amplifier characteristic changes deteriorates
Solution Approach 1:
The patent segments the compensation process into multiple independent bands, with each band having its own amplitude and phase compensation coefficients. This segmentation allows the system to adapt to different frequency components independently, improving adaptability while keeping the calculation for each band relatively simple and manageable.
Solution Approach 2:
The system dynamically adjusts the compensation coefficients for each band based on real-time error detection, enabling adaptation to amplifier characteristic changes without requiring a complete recalculation of all coefficients, thus maintaining calculation efficiency.
3Reliability
If amplitude and phase control is implemented for multiple bands, then distortion compensation effectiveness improves, but the device complexity increases
Solution Approach 1:
The patent divides the frequency spectrum into multiple bands and applies independent amplitude and phase control to each band. This segmentation approach improves distortion compensation effectiveness by addressing different frequency components separately, while the modular structure keeps the overall circuit design manageable and systematic.
Data Source
AI summary
An amplitude and phase control device includes a signal dividing unit to divide a transmission signal into first and second signals and output the first and second signals to a Doherty amplifier, an error calculating unit to acquire, from the Doherty amplifier, a synthesized signal of first and second signals amplified by the Doherty amplifier, multiply the synthesized signal by a reciprocal of a gain of the Doherty amplifier, and calculate an error between a synthesized signal after being multiplied by the reciprocal and the transmission signal, and a controlling unit to control an amplitude of each of the first signal and the second signal output from the signal dividing unit depending on the error calculated by the error calculating unit, and control a phase difference between the first signal output from the signal dividing unit and the second signal output from the signal dividing unit depending on the error.