Serializer Interface Latch Polarity for Multicycle Path Timing
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Solution Overview
Problem
Conventional serializer interfaces face challenges in meeting timing requirements at high data rates due to increased clock load and network depth, leading to issues in clock distribution and jitter requirements, especially at the C16-C8 interface, which are not effectively addressed by traditional methods.
Innovation Solution
A replica-based synchronous delay detection scheme is employed to determine an optimal delay window by sampling step responses at a first clock edge and synchronizing a second clock edge, configuring the polarity of latches in the serializer chain, and controlling the multicycle path based on this configuration to manage clock direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional clock distribution methods are used at high data rates, then the serializer interface can operate, but timing requirements cannot be met due to increased clock load and network depth
Solution Approach 1:
The patent segments the clock distribution system into multiple hierarchical levels (C16 clock domain and C8 clock domain) with dedicated delay detection and control mechanisms at each level. This segmentation allows independent optimization of timing parameters at different clock rates, enabling compliance with stringent timing requirements at 224 Gbps while managing overall system complexity through modular design.
2Manufacturing precision
If replica-based synchronous delay detection is implemented, then optimal delay window can be determined and multicycle path controlled, but device complexity increases
Solution Approach 1:
The patent employs replica serializers that copy the functional behavior of actual serializers but are dedicated solely to delay detection. These replica units replicate the critical timing paths without requiring full operational functionality, enabling precise delay window measurement (within 0.5 UI accuracy) while reducing complexity compared to using full operational serializers for detection purposes.
3Loss of time
If latch polarity is dynamically configured based on delay detection, then multicycle path timing is optimized, but control complexity increases
Solution Approach 1:
The patent implements a feedback mechanism where delay detection results from replica serializers directly control the polarity configuration of latches in the actual serializer chain. The delay detection unit measures the actual timing characteristics and feeds this information back to automatically adjust latch polarity, optimizing multicycle path timing while keeping control logic complexity manageable through automated closed-loop control.
4Reliability
If clock direction is controlled based on replica serializer delay detection, then timing constraints are met, but power consumption increases
Solution Approach 1:
The patent performs delay detection and clock direction configuration as a preliminary action during serializer initialization or mode switching, rather than continuously during operation. The replica serializers detect optimal delay parameters in advance, and this configuration is stored and reused, enabling timing constraint compliance while minimizing power consumption by avoiding continuous detection and adjustment operations.
Data Source
AI summary
Various example embodiments herein provide methods, circuits, and systems, for controlling a multicycle path in a serializer interface. The method includes determining a desired delay window of a multicycle data path in a serializer interface by sampling at least one step response from serializer delay replica circuitry at an edge of a first clock signal and a gating signal, in response to synchronizing a second clock signal with a negative edge of the first clock signal, configuring a polarity of a latch in a subsequent serializer of a serializer chain based on the determined desired delay window, and controlling the multicycle data path in the serializer interface based on the configured polarity of the latch in the subsequent serializer of the serializer chain.