Forward Strobe Clock Recovery for Bit-Deskewed Data Reception
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Solution Overview
Problem
Current data transfer methods, both serial and parallel I/O interfaces, face challenges in synchronization due to signal jitter and skew, leading to increased complexity and bandwidth overhead, particularly in achieving high data rates without introducing noise and pin count increases.
Innovation Solution
A bit-deskewing method and system that includes a forward strobe clock recovery circuit and data bit clock recovery circuits to align sampling clocks, allowing the data bit sampling clock to track the forward strobe sampling clock, thereby improving sampling accuracy and reducing complexity and overhead.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If per-line closed-loop timing with clock recovery is used in serial links, then synchronization accuracy is improved, but bandwidth overhead and complexity increase due to encoding requirements
Solution Approach 1:
The patent extracts the clock signal from the data stream by using a separate forward strobe signal transmitted alongside data bits. The receiver uses a forward strobe clock recovery circuit to extract timing information from this dedicated strobe signal, eliminating the need for complex encoding schemes required in traditional serial links.
Solution Approach 2:
The patent segments the data transmission into separate channels: data bits are transmitted on one channel while the forward strobe signal is transmitted on another channel. This segmentation allows independent optimization of each channel, with the strobe channel dedicated solely to timing information and the data channel dedicated to information transfer.
2Measurement precision
If source-synchronous timing with strobe alignment is used in parallel links, then sampling accuracy is improved, but trace impedance and length matching requirements increase complexity
Solution Approach 1:
The patent implements per-bit deskewing where each bit receiver can delay the strobe by a different amount to place its own clock at the center of its own data. This local adjustment allows each receiver to optimize its sampling point independently without requiring global trace matching across all data lines.
3Measurement precision
If per-bit deskewing is implemented in parallel links, then sampling accuracy is improved, but noise on the strobe signal increases and timing budget is reduced
Solution Approach 1:
The patent merges the clock recovery functions for both the forward strobe and data bits into a unified system. The forward strobe clock recovery circuit provides a reference that is used to generate the data bit sampling clocks, ensuring coherent timing across all channels while reducing noise through correlated processing.
4Measurement precision
If a strobe is transmitted for each data bit rather than for a group of bits, then sampling accuracy is improved, but pin counts and cost increase
Solution Approach 1:
The forward strobe signal serves multiple functions: it provides timing information for sampling, enables per-bit deskewing through individual delay adjustments, and acts as a reference for the data bit sampling clocks. This multi-functionality allows accurate sampling without requiring separate strobe lines for each bit.
Data Source
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AI summary
A method for receiving data comprising responsive to receiving a forward strobe, a forward strobe clock recovery circuit aligning a forward strobe sampling clock; and aligning a data bit sampling clock to track the forward strobe sampling clock during operation.