Feedforward Amplifier Cascade With Local Error Correction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current feedforward correction systems in wireless communication systems suffer from low efficiency due to coupling loss and inefficiency in error amplifiers, especially at low average error voltages with high peak-to-average ratios, while digital predistortion techniques struggle to counteract noise and handle certain types of distortion poorly, especially in systems with large bandwidths and low output power.
Innovation Solution
The proposed solution involves an amplifier circuit with a cascade of sub-amplifiers and interspersed feedforward error correction blocks, allowing local error correction between amplifier sections at lower relative amplitudes, using directional error amplifiers to replace traditional couplers and error injection systems, optimizing coupling factors and error amplifier efficiency across different amplitude ranges.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If traditional coupler-based feedforward correction is used, then error correction can be applied, but coupling loss reduces efficiency especially at low average error voltages
Solution Approach 1:
The amplifier cascade is divided into multiple sub-amplifier stages with interspersed error correction blocks, allowing error correction to be applied at intermediate points rather than only at the final output. This segmentation enables correction of errors at lower amplitude levels where coupling loss is less problematic.
Solution Approach 2:
Different error correction blocks are strategically placed at different positions in the cascade, with each block optimized for the local amplitude and error characteristics at that stage. This local optimization reduces overall coupling loss by matching correction strength to local needs.
2Manufacturing precision
If error correction is applied at high amplitudes, then linearity is improved, but power loss increases due to coupling loss and error amplifier inefficiency
Solution Approach 1:
Error correction is performed preliminarily at intermediate stages before the signal reaches full amplitude. By correcting errors at lower amplitude levels in the cascade, the system achieves cumulative linearity improvement without the power loss penalties of high-amplitude correction.
Solution Approach 2:
Multiple error correction blocks are distributed throughout the cascade to provide continuous error correction across the amplification process. This continuous correction approach maintains linearity throughout the signal path rather than attempting single-stage correction at high power.
3Loss of energy
If digital predistortion is used, then efficiency is maintained, but the technique cannot counteract noise and handles certain distortion poorly
Solution Approach 1:
The feedforward error correction blocks act as intermediaries between the digital predistortion and the final output, providing additional noise counteraction and distortion handling capabilities that predistortion alone cannot provide.
Data Source
AI summary
An amplifier circuit for compensating an output signal provided at an output of the amplifier circuit comprises a cascade of sub-amplifiers. Each sub-amplifier of the cascade contributes to a respective part of the output signal. The cascade of sub-amplifiers comprises an end sub-amplifier and at least one preliminary sub-amplifier. At least one error correction block is coupled to apply feedforward error correction to an output of one of the at least one preliminary sub-amplifier.