Interconnect Repair Chains With 2:1 Multiplexing for Low Delay
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Solution Overview
Problem
Current interconnect repair strategies in 2.5D and 3D chip designs, such as those outlined in the UCIe standard, introduce significant propagation delays and require complex multiplexing schemes, consuming excessive silicon area and control signals due to the use of three-to-one multiplexers for repairing defective interconnects.
Innovation Solution
Implementing a design with a plurality of repair chains, each containing a single spare interconnect, and using two-to-one multiplexers to efficiently reroute signal paths, minimizing propagation delay and silicon area by ensuring spatially neighboring interconnects belong to different repair chains.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If three-to-one multiplexers are used for interconnect repair as per UCIe standard, then defective interconnects can be repaired, but propagation delay increases significantly and silicon area is excessively consumed
Solution Approach 1:
The patent divides the interconnect array into multiple repair chains, where each chain contains a sequence of interconnects and a single spare interconnect. This segmentation allows repairs to be performed using simpler two-to-one multiplexers along each chain, avoiding the need for complex three-to-one multiplexers and reducing propagation delay while maintaining repair capability.
Solution Approach 2:
The patent reorganizes the repair architecture from a planar arrangement with two spares per half-bus to a chain-based arrangement extending in one dimension. Each repair chain processes interconnects sequentially, transforming the repair problem into a series of two-to-one multiplexing decisions rather than a single complex three-to-one multiplexing operation.
2Reliability
If three-to-one multiplexers are used for interconnect repair, then defective interconnects can be repaired, but silicon area requirements increase excessively
Solution Approach 1:
By segmenting the interconnect repair function into multiple repair chains with two-to-one multiplexers, the patent reduces the silicon area required compared to using a single three-to-one multiplexer. The segmented approach distributes the multiplexing logic across chains, reducing overall area consumption while maintaining full repair capability.
3Reliability
If three-to-one multiplexers are used for interconnect repair, then defective interconnects can be repaired, but the number of control signals increases
Solution Approach 1:
The patent segments the control logic into multiple repair chains, where each chain uses two-to-one multiplexers with fewer control signals. This segmentation reduces the total number of control signals required compared to a centralized three-to-one multiplexer approach, while maintaining the ability to repair all defective interconnects.
4Reliability
If spare interconnects are placed at extremes of half-bus as per UCIe standard, then repair coverage is provided, but signal path offset distance increases causing timing delays
Solution Approach 1:
The patent segments the interconnect array into multiple repair chains distributed across the array, rather than concentrating spares at the extremes. This segmentation ensures that every interconnect is at most one position away from a spare within its chain, minimizing signal path offset distance and avoiding timing delays while maintaining comprehensive repair coverage.
Data Source
AI summary
An integrated circuit comprising: a plurality of interconnects forming at least four repair chains, each repair chain comprising: a plurality of primary interconnects for providing a signal path, a spare interconnect, and circuitry configured for offsetting, within each repair chain, signal paths so as to avoid the use of a defective primary interconnect, when present, within the repair chain, wherein one signal path is offset to the spare interconnect, wherein the plurality of interconnects is arranged so that spatially neighboring interconnects belong to different repair chains.