Adaptive Strobe Gating for Timing Drift and Jitter Tolerance
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Solution Overview
Problem
In strobe-timed signaling systems, the narrow timing margins due to chip-to-chip timing drift and reference clock jitter limit the ability to increase signaling bandwidth, making it challenging to suppress overhead strobe edges effectively.
Innovation Solution
An adaptive strobe gating signal is generated based on timing events in the incoming strobe signal, creating a gating window that drifts with the strobe signal, thereby expanding the tolerable drift between the incoming and receive-side timing domains, improving skew tolerance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If direct gating mode is used to suppress overhead strobe edges, then the gating signal can be generated simply, but the timing margin is too narrow to tolerate chip-to-chip drift and clock jitter
Solution Approach 1:
An adaptive gate synthesizer circuit is introduced as an intermediary component that receives both the incoming strobe signal and a gate enable signal, then synthesizes an adaptive gating signal by detecting strobe edges and generating corresponding gate pulses. This mediator handles the complex timing adjustments and skew compensation, isolating the simpler gate enable logic from the demanding timing margin requirements.
Solution Approach 2:
The adaptive gate synthesizer uses feedback by monitoring the incoming strobe signal edges and adjusting the gating signal timing dynamically. The circuit detects strobe transitions and generates gate pulses with appropriate timing margins, automatically compensating for drift and jitter through this closed-loop edge-detection mechanism.
2Adaptability or versatility
If the gating window is fixed relative to the receive-side timing domain, then the gating logic is simple, but it cannot accommodate timing drift between transmit and receive domains
Solution Approach 1:
The gating window is transformed from a static fixed-time interval to a dynamic adaptive window that moves with the strobe signal edges. The adaptive gate synthesizer continuously adjusts the gating window position and duration based on detected strobe transitions, enabling the system to track and accommodate timing drift between transmit and receive domains dynamically.
Solution Approach 2:
The gate enable signal provides preliminary control by asserting when data bursts are expected, allowing the adaptive gate synthesizer to prepare and configure the gating window in advance. This preliminary assertion triggers the synthesizer to detect upcoming strobe edges and establish the appropriate gating timing before data arrival.
3Productivity
If the interval between preamble transition and first active strobe edge is reduced to minimize overhead, then bandwidth increases, but the margin for gating signal timing error decreases
Solution Approach 1:
The system changes the timing parameters of the gating signal dynamically based on detected strobe edge positions. Rather than using a fixed gating window that requires large margins, the adaptive synthesizer adjusts gate pulse width and timing parameters to match the actual strobe signal characteristics, enabling tighter bandwidth optimization while maintaining sufficient timing margins through parameter adaptation.
Data Source
AI summary
A gating signal for masking overhead transitions in a timing signal is generated adaptively based on timing events in the incoming timing signal itself to yield a gating window that opens and closes deterministically with respect to active edges of the timing signal.