Non-linear Neural Network Equalizer for High-Speed SERDES Channels
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Solution Overview
Problem
High-speed SERDES links on integrated circuit devices suffer from significant non-linearity due to insertion loss, inter-symbol-interference, and other channel impairments, which linear equalization methods are insufficient to compensate, especially when data levels are close together.
Innovation Solution
Implementing a non-linear equalizer, such as a multi-layer perceptron neural network equalizer, with adaptation circuitry that uses cost functions like mean square error or cross-entropy to adapt parameters, and incorporating decision-feedback equalization to mitigate inter-symbol interference, effectively remapping signal samples into a different space for correct separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If linear equalization is used, then device complexity is reduced, but measurement precision deteriorates due to insufficient compensation of non-linearities
Solution Approach 1:
The patent transforms the linear equalization parameters into non-linear parameters by introducing neural network weights and activation functions. The equalizer transitions from using simple linear coefficients to using learnable non-linear parameters that can adapt to channel characteristics, thereby improving signal detection accuracy while managing complexity through efficient neural network architectures.
Solution Approach 2:
The patent replaces the traditional mechanical/mathematical linear equalization system with a neural network-based system. Instead of using fixed linear filters, the system employs neural networks with non-linear activation functions that can learn and adapt to complex channel impairments, substituting a more sophisticated computational approach for the simpler linear method.
2Measurement precision
If non-linear equalization is implemented, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent segments the non-linear equalization task into multiple manageable components: feature extraction layers, non-linear transformation layers, and decision-making layers. By dividing the neural network into distinct functional blocks, the system achieves high measurement precision through complex non-linear processing while keeping the overall device complexity manageable through modular architecture.
Solution Approach 2:
The patent extends the equalization process from the traditional one-dimensional linear filtering domain to a higher-dimensional non-linear feature space. By introducing multiple layers of non-linear transformations, the system maps input signals into a more complex feature space where channel impairments can be more effectively separated, improving detection accuracy while the layered structure manages computational complexity.
3Productivity
If data levels are kept close together for high-order signaling, then productivity is improved, but measurement precision deteriorates due to non-linear channel effects
Solution Approach 1:
The patent applies preliminary non-linear transformations to the received signal before final detection. By pre-processing the signal through neural network layers that learn to compensate for channel non-linearities, the system prepares the signal in advance for accurate detection, enabling close data levels to be distinguished despite channel impairments and thus maintaining high data transmission rates.
Solution Approach 2:
The patent incorporates feedback mechanisms where the neural network learns from detection errors and adjusts its parameters accordingly. Through adaptive training and refinement, the system improves its ability to distinguish close data levels over time, maintaining high measurement precision even for high-order signaling schemes with closely spaced constellation points.
Data Source
AI summary
A receiver for use in a data channel on an integrated circuit device includes a non-linear equalizer having as inputs digitized samples of signals on the data channel, decision circuitry configured to determine from outputs of the non-linear equalizer a respective value of each of the signals, and adaptation circuitry configured to adapt parameters of the non-linear equalizer based on respective ones of the value. The non-linear equalizer may be a neural network equalizer, such as a multi-layer perceptron neural network equalizer, or a reduced complexity multi-layer perceptron neural network equalizer. A method for detecting data on a data channel on an integrated circuit device includes performing non-linear equalization of digitized samples of input signals on the data channel, determining from output signals of the non-linear equalization a respective value of each of the output signals, and adapting parameters of the non-linear equalization based on respective ones of the value.


