Data Beat Delay Circuit for Clock Alignment in Memory Interfaces
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Solution Overview
Problem
In integrated circuits, inherent delays in signal paths can cause timing mismatches during data transmissions, leading to potential setup and hold time violations, which existing compensation circuitry like DLLs may not fully address, especially due to insertion delays in clocked storage circuits.
Innovation Solution
A delay circuit within the memory controller is configured to receive data transmitted in beats and apply adjustable delays to align the data with the clock signal, using a combination of pipelines and DLLs for fine-grain adjustments to prevent setup and hold time violations, while also compensating for insertion delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a DLL is used to delay the clock signal for timing alignment, then timing mismatches can be compensated, but the adjustment range is limited and may cause setup and hold time violations
Solution Approach 1:
The delay compensation function is segmented into two independent parts: a DLL for fine-grain delay adjustment of the clock signal, and a separate delay circuit for coarse delay adjustment of the data signal. This segmentation allows each component to operate within its optimal adjustment range without causing timing violations.
Solution Approach 2:
The delay circuit acts as an intermediary component between the data source and the memory interface. It introduces a controllable delay to the data signal path to match the clock signal timing, effectively mediating the timing mismatch without requiring extensive modification of the DLL adjustment range.
2Reliability
If the DLL delay is increased to compensate for insertion delay, then timing alignment improves, but setup and hold time violations occur
Solution Approach 1:
The total required delay is segmented between two independent circuits: the DLL provides fine-grain adjustment (e.g., in picosecond increments) for precise timing alignment, while the delay circuit provides coarse delay adjustment. This prevents the DLL from being over-adjusted beyond its safe operating range.
Solution Approach 2:
The system dynamically distributes the delay burden between the DLL and the delay circuit based on the total required compensation. The delay circuit handles the bulk of the insertion delay compensation, while the DLL provides fine-tuning, creating a flexible and adaptive timing correction system.
Data Source
AI summary
A method and apparatus for delay compensation in data transmission is disclosed. In one embodiment, an IC is configured to transmit data along with a clock signal to which the data is synchronized at the receiver. The IC includes a delay circuit configured to receive the data, which is transmitted in beats. The delay circuit includes a number of pipelines corresponding to the number of beats. Beats of data input into the delay circuit are routed to particular ones of the pipelines in accordance with a desired amount of delay. The delay applied to the data may be set to align the data with the clock signal at the receiver and to compensate for inherent delays that affect the clock signal.