Clock Synchronization via Delay-Matched Interconnects
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Solution Overview
Problem
Existing methods for reducing clock skew between multiple clock domains in multi-chip packaging and 3D integrated circuits face challenges, particularly in introducing additional delay and noise due to the need for deeper FIFO pipelines, which negatively impact processor performance.
Innovation Solution
An apparatus that synchronizes clock edges across multiple dies using delay-matched interconnects and phase interpolators, with a delay estimator and control logic to align clock signals, potentially reducing or eliminating the need for FIFO pipelines and minimizing latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If delay-line based skew compensators are used to reduce clock skew, then clock skew is reduced, but additional delay and supply noise induced jitter are introduced
Solution Approach 1:
The patent extracts the skew compensation function from traditional delay-line based compensators and implements it through matched delay paths in the interconnect structure itself. The clock signal is distributed through matched interconnect paths that inherently provide delay matching without requiring separate compensator circuits, thereby eliminating the additional delay and jitter introduced by traditional skew compensators.
Solution Approach 2:
The patent creates equipotential delay paths by designing matched interconnect structures that provide equal propagation delay for clock signals traveling between dies. The matched delay paths ensure that clock edges arrive at corresponding clock domains simultaneously, achieving skew reduction through structural symmetry rather than active compensation mechanisms.
2Reliability
If deeper FIFO pipelines are used to cope with large clock skews, then clock skew tolerance is improved, but latency increases
Solution Approach 1:
The patent performs preliminary clock synchronization by distributing synchronized clock edges to all clock domains before data transfer operations begin. The matched delay interconnect paths pre-align the clock phases across dies, eliminating the need for deep FIFO pipelines that would otherwise be required to absorb clock skew variations. This preliminary synchronization reduces latency while maintaining reliability.
3Manufacturing precision
If skew compensators are used to reduce clock skew, then clock synchronization is improved, but device complexity increases
Solution Approach 1:
The patent merges the clock distribution function with the delay matching function by integrating matched delay paths directly into the interconnect structure. Instead of separate skew compensator circuits, the interconnect paths themselves are designed to provide matched delays, combining multiple functions into a unified structure and reducing overall device complexity.
Data Source
AI summary
Described is an apparatus for clock synchronization. The apparatus comprises a pair of interconnects; a first die including a first phase interpolator having an output coupled to one of the interconnects; and a second die, wherein the pair of interconnects is to couple the first die to the second die.