Analog Pre-Distortion Circuit for RF Power Amplifier Linearity
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Solution Overview
Problem
Power amplifiers in 5G wireless communication systems experience linearity response deviations, leading to out-of-band spectral regrowth and in-band distortion due to compression, which degrade RF performance.
Innovation Solution
An analog pre-distortion (APD) circuit is coupled to the power amplifier to receive a control signal corresponding to linearity response deviations, processing the RF signal to reduce these deviations and improve linearity and RF performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the power amplifier operates under compression condition to achieve higher output power, then the output power is increased, but linearity response deviation occurs leading to out-of-band spectral regrowth and in-band distortion
Solution Approach 1:
The APD circuit performs preliminary processing on the RF signal before it enters the power amplifier. By pre-distorting the signal in the opposite direction of the expected non-linearity, the system compensates for the power amplifier's compression effects, allowing high output power operation while maintaining linearity accuracy.
Solution Approach 2:
The system uses feedback mechanisms to detect linearity response deviation and dynamically adjusts the APD circuit's pre-distortion parameters. This closed-loop control ensures that the pre-processing adapts to changing operating conditions, maintaining optimal linearity compensation across different power levels.
2Productivity
If the power amplifier operates under compression condition to achieve higher data rates, then the data transmission capability is improved, but out-of-band spectral regrowth and in-band distortion increase
Solution Approach 1:
The APD circuit applies pre-distortion to the RF signal before amplification, anticipating and counteracting the non-linear effects that would otherwise cause spectral regrowth and distortion. This preliminary correction enables the system to operate in compression mode for high data rates while suppressing harmful spectral effects.
Solution Approach 2:
The system converts the inherently harmful non-linear compression effects into a benefit by measuring and storing the distortion characteristics, then using this information to create compensating pre-distortion signals. The harmful non-linearity becomes the basis for its own cancellation.
Data Source
AI summary
A power amplifier linearization circuit and related apparatus is provided. In examples disclosed herein, the power amplifier linearization circuit includes an analog pre-distortion (APD) circuit coupled to an input of a power amplifier. Notably, the power amplifier can exhibit linearity response deviation, namely linearity amplitude response deviation and linearity phase response deviation, when amplifying a radio frequency (RF) signal under a compression condition. As such, the APD circuit is configured to receive a control signal corresponding to the linearity response deviation and pre-process the RF signal based on the control signal before providing the RF signal to the power amplifier. As a result, it may be possible to reduce the linearity response deviation in the power amplifier, thus helping to improve linearity and RF performance of the power amplifier.