High-Speed Transmitter LUT Compensation for Dynamic Distortion
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Solution Overview
Problem
High-speed transmitters face dynamic distortion issues due to dependencies on previous and subsequent symbols, which existing compensation methods are inadequate in addressing, leading to suboptimal data transfer performance.
Innovation Solution
A digital compensation technique using a lookup table (LUT) and shift registers to adjust input values for a digital-to-analog converter (DAC), iteratively updating LUT values with a least mean squared (LMS) algorithm to remove dynamic distortion and introduce desirable signal characteristics like equalization and amplitude scaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional compensation methods are used, then device complexity is reduced, but dynamic distortion compensation effectiveness deteriorates
Solution Approach 1:
The patent segments the dynamic distortion compensation into multiple independent components: a lookup table (LUT) for storing pre-calculated compensation values, shift registers for symbol sequencing, and an LMS algorithm for iterative optimization. This segmentation allows each component to perform a specific function efficiently, achieving effective distortion compensation without requiring a monolithic complex device.
Solution Approach 2:
The patent introduces a lookup table as an intermediary element that stores pre-computed compensation values for different symbol sequences. This LUT acts as a mediator between the input symbols and the distortion compensation process, enabling the system to apply complex compensation without real-time computational complexity, thus resolving the contradiction between effectiveness and device complexity.
2Productivity
If high-speed transmission is implemented, then data transfer rate is improved, but dynamic distortion increases
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing compensation values in the lookup table before actual data transmission occurs. The LUT contains pre-determined correction values for various symbol sequences, allowing the high-speed transmitter to apply distortion compensation without real-time computation delays, thus maintaining both high data transfer rates and effective distortion reduction.
Solution Approach 2:
The patent implements feedback through the LMS (Least Mean Squares) algorithm, which iteratively optimizes the lookup table values based on actual transmission performance. This feedback mechanism allows the system to adapt to changing conditions and refine distortion compensation over time, enabling sustained high-speed transmission with minimized dynamic distortion effects.
Data Source
AI summary
A transmitter includes a shift register, a lookup table, and a digital to analog converter. The shift register is configured to receive an input signal and to output delayed copies of the input signal. The lookup table is configured to store compensation values estimated based on the input signal and the delayed copies of the input signal. The digital to analog converter is configured to output a transmit signal based on the input signal and the compensation values. The compensation values are designed to mitigate distortion of the transmit signal from conversion of the input signal to a digital signal.