Power Amplifier Input Correction for SMPS-Induced RF Distortion
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Solution Overview
Problem
Power amplifiers in radio frequency transmission systems suffer from distortions due to the time-varying output of switched mode power supplies (SMPS), leading to unwanted modulation and deteriorated signal quality, which current techniques fail to completely correct by not accounting for distortions in the supply voltage.
Innovation Solution
A method and apparatus that determine and apply correction factors to the input signal of a power amplifier based on estimated characteristics of the distorted time-varying supply voltage from the SMPS, using a processor and interface to correct amplitude and phase errors in the radio frequency output signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a switched mode power supply is used to extend battery life, then energy efficiency is improved, but signal quality deteriorates due to voltage ripples and distortions
Solution Approach 1:
The system performs preliminary characterization of the power supply distortions and pre-calculates correction factors before signal transmission. The distortion characteristics are measured during calibration phases, and correction lookup tables are prepared in advance, allowing real-time compensation without adding complex runtime processing.
Solution Approach 2:
The system implements feedback by continuously monitoring the actual signal quality and adjusting correction factors dynamically. The measured distortions from the SMPS are fed back into the correction algorithm, enabling adaptive compensation that maintains signal quality despite variations in power supply behavior under different operating conditions.
2Reliability
If distortion correction is applied prior to the power amplifier, then signal quality improves, but correction effectiveness is reduced because supply voltage distortions are not accounted for
Solution Approach 1:
The invention merges the distortion correction process with the power amplifier control system. By integrating the correction factors directly into the amplifier's input signal path and combining them with the main signal processing chain, the system achieves comprehensive correction that accounts for both pre-amplifier and power supply distortions in a unified manner.
Solution Approach 2:
The system changes parameters by dynamically adjusting correction factors based on measured power supply distortion characteristics. Instead of using fixed correction values, the system modifies amplitude and phase parameters in real-time according to the actual SMPS behavior, enabling accurate compensation under varying operating conditions.
3Reliability
If SMPS switching frequency is adjusted to move ripple outside desired frequency band, then signal quality improves, but power supply efficiency deteriorates
Solution Approach 1:
The system changes the switching frequency parameter of the SMPS to optimize the trade-off between signal quality and power efficiency. By adjusting the frequency to positions that minimize both ripple impact on signal quality and energy losses in the switching components, the system achieves dual optimization without requiring excessive filtering or complex control mechanisms.
Data Source
AI summary
A solution is provided for correcting distortions on a radio frequency output signal of a power amplifier. There is provided an apparatus, comprising: a processor configured to determine at least one correction factor for a distortion on a radio frequency output signal of a power amplifier on the basis of estimated characteristics of a distorted time-varying supply voltage from a power supply to a power amplifier and an interface configured to feed the at least one correction factor to an input signal of the power amplifier.