AC Coupled Crosstalk Cancellation Circuit
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Solution Overview
Problem
Existing computer systems face significant challenges in effectively mitigating far end crosstalk, particularly in single-ended data lines, as passive methods are limited and active methods incur high costs and complexity, while current solutions for active crosstalk cancellation often result in negative loading and limited performance improvements.
Innovation Solution
A transmit crosstalk cancellation approach using an alternating current (AC) coupled pulse is implemented, with an auxiliary driver AC coupled to the victim data line via a capacitor, allowing for optimized far end crosstalk cancellation without significant platform cost, enabling higher signaling rates and simplified training procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If passive crosstalk mitigation methods are used, then implementation cost is reduced, but crosstalk cancellation effectiveness is limited
Solution Approach 1:
The patent introduces an intermediary AC coupling circuit between the aggressor signal source and the victim data line. This circuit includes a capacitor and a transimpedance amplifier that converts the capacitive coupling current into a voltage signal, enabling active crosstalk cancellation while maintaining cost-effectiveness through simplified circuit architecture.
Solution Approach 2:
The patent dynamically adjusts the gain parameter of the transimpedance amplifier based on calibration data to optimize crosstalk cancellation effectiveness. The system adapts the amplifier gain to match the specific crosstalk characteristics of different aggressor-victim line pairs, improving cancellation performance without requiring complex fixed-parameter designs.
2Reliability
If active crosstalk cancellation methods are used, then crosstalk cancellation effectiveness is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts only the essential functional elements needed for crosstalk cancellation: the AC coupling capacitor and the transimpedance amplifier. By removing unnecessary components from traditional active cancellation circuits, the design achieves effective crosstalk mitigation with reduced complexity and lower cost.
Solution Approach 2:
The transimpedance amplifier serves multiple functions: it converts the capacitive coupling current to voltage, amplifies the signal to appropriate levels, and provides the inverted polarity needed for crosstalk cancellation. This multi-functionality reduces the need for separate dedicated circuits, simplifying the overall system.
3Reliability
If conventional active crosstalk cancellation is implemented, then crosstalk reduction is achieved, but negative loading and limited performance improvements occur
Solution Approach 1:
The patent employs periodic AC coupling through the capacitor, which allows the crosstalk cancellation signal to be injected only during the active signal transmission periods. This periodic action prevents continuous loading on the victim line, avoiding negative loading effects while maintaining effective crosstalk reduction during data transmission.
Solution Approach 2:
The patent replaces traditional voltage-mode active cancellation mechanisms with a current-mode approach using the transimpedance amplifier. This substitution allows the cancellation signal to be derived from the existing capacitive coupling current rather than requiring additional voltage driving, thereby reducing loading effects on the communication channel and enabling higher signaling rates.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively reduces far end crosstalk, increases communication bandwidth, and lowers costs, while allowing implementation on one side of the communication channel, thus enhancing system performance without requiring changes to existing specifications.
Implementation Method 1
an auxiliary driver AC coupled to the victim data line via a capacitor
Data Source
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AI summary
An apparatus comprises a first data line coupled to a first driver; a second data line coupled to a second driver; and a crosstalk cancelation circuit comprising a third driver coupled between the first data line and the second data line, the crosstalk cancelation circuit to compensate for far end crosstalk introduced from the first data line to the second data line.