Programmable Adaptive Equalization for Multi-Protocol PLD Receivers
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Solution Overview
Problem
High-speed communication protocols require adaptive equalization in receiver circuitry to compensate for signal attenuation and phase shift, but existing programmable logic devices (PLDs) lack the flexibility to automatically determine the necessary equalization parameters, such as the number of taps, tap spacing, coefficient starting values, error signal generation, and sampling point, which can vary depending on the specific communication system.
Innovation Solution
The PLD circuitry is designed to be programmable in aspects like the number of taps, tap spacing (integer or fractional), coefficient determination, error signal type, training pattern usage, and sampling point location within the bit period, allowing users to configure these parameters manually or through algorithms for adaptive equalization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If fixed equalization parameters are used in PLDs, then device complexity is reduced, but adaptability to different communication protocols and channel conditions deteriorates
Solution Approach 1:
The equalization circuitry is designed with programmable parameters including the number of taps, tap spacing (integer or fractional), coefficient determination methods, error signal generation approaches, training pattern usage, and sampling point location. These dynamic parameters allow the PLD to adapt its equalization characteristics to match different communication protocols and channel conditions, resolving the contradiction between fixed complexity and adaptability.
2Adaptability or versatility
If adaptive equalization capability is added to PLDs, then versatility across communication protocols is improved, but device complexity increases
Solution Approach 1:
The equalization circuitry is designed as a universal, multi-functional block that can operate with different configurations of taps, spacing, coefficient methods, error signal generation, and training patterns. This single versatile circuit replaces the need for multiple protocol-specific equalization circuits, achieving adaptability without proportionally increasing overall device complexity.
3Adaptability or versatility
If manual configuration of equalization parameters is required, then adaptability is improved, but ease of operation deteriorates
Solution Approach 1:
The equalization circuitry incorporates automatic adaptation capabilities where the system can self-configure its parameters based on detected channel conditions. The circuitry automatically determines optimal tap coefficients, selects appropriate training patterns, and adjusts sampling points without requiring manual intervention, thereby maintaining adaptability while significantly improving ease of operation.
Solution Approach 2:
The system implements feedback mechanisms through error signal generation and coefficient determination processes that continuously monitor equalization performance and automatically adjust parameters. This closed-loop feedback enables the circuit to adapt to changing channel conditions in real-time without user intervention, resolving the contradiction between adaptability and operational simplicity.
Data Source
AI summary
A programmable logic device is provided with adaptive equalization circuitry that is programmable in one or more respects. Examples of the programmable aspects of the equalization circuitry are (1) the number of taps used, (2) whether integer or fractional spaced taps are used, (3) what starting values are used in the computation of coefficient values, (4) whether satisfactory coefficient values are computed only once or on an on-going basis, (5) whether an error signal is generated using a decision directed algorithm or using a training pattern, (6) what training pattern (if any) is used, and/or (7) the location of the sampling point in the bit period of the signal to be equalized.