Dedicated Routing Resources for Low-Skew Stacked IC Interconnects

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Solution Overview

Problem

Existing programmable logic devices, such as FPGAs, face challenges in creating low-skew buses between stacked ICs due to varying signal delays through their routing resources, and the availability of programmable routing resources is design-dependent, making it uncertain if a low-skew bus can be implemented.

Innovation Solution

The implementation of dedicated routing resources on programmable integrated circuits, including interface tiles and interposers, to electrically couple pins between ICs, providing a low-skew path independent of the conventional programmable interconnect structure.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional programmable routing resources are used to interconnect stacked ICs, then routing flexibility is maintained, but signal delay skew varies significantly and low-skew buses cannot be guaranteed

Engineering Contradiction:

Improvesignal delay consistencyVSAvoidrouting resource availability

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent segments the routing resources into two distinct types: conventional programmable routing resources for general-purpose connections and dedicated low-skew routing resources specifically for time-critical interconnections between stacked ICs. This segmentation allows the system to guarantee low skew for critical paths while maintaining routing flexibility for other connections.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces dedicated low-skew routing resources as an intermediary pathway between stacked ICs. These dedicated resources act as a specialized mediator that ensures consistent signal delay for inter-IC communications, separating the time-critical routing function from the general-purpose programmable routing fabric.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If dedicated routing resources are added to ensure low-skew interconnections, then signal delay consistency improves, but device complexity and manufacturing cost increase

Engineering Contradiction:

Improvelow-skew bus guaranteeVSAvoidrouting resource structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The dedicated low-skew routing resources are designed to serve multiple functions: they provide guaranteed low-skew paths for inter-IC communications, can be configured for different signal types, and work in conjunction with the programmable routing fabric. This multi-functionality justifies the added complexity by providing versatile low-skew connectivity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent applies local quality by providing dedicated low-skew routing resources specifically where needed for inter-IC connections, rather than making the entire routing fabric dedicated. This localized approach to quality enhancement minimizes the overall device complexity while ensuring low skew where it is most critical.

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If programmable routing resources are used, then routing adaptability to different designs is maintained, but there is no guarantee that a low-skew bus can be implemented

Engineering Contradiction:

Improvedesign flexibilityVSAvoidlow-skew bus implementation

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The routing resources are segmented into dedicated low-skew paths for time-critical applications and programmable paths for design-specific routing needs. This segmentation ensures that adaptability is maintained for general routing while reliability is guaranteed for low-skew requirements.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The dedicated low-skew routing resources are self-configuring and automatically available for inter-IC connections, requiring no additional design effort to guarantee low skew. Meanwhile, the programmable routing resources continue to adapt to different design requirements independently.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS7619441B1Apparatus for interconnecting stacked dice on a programmable integrated circuit

Publication Date: 2009.11.17 XILINX INC

AI summary

An apparatus for interconnecting stacked dice on a programmable integrated circuit is described. In one example, an integrated circuit die comprises a programmable integrated circuit that includes first and second interface tiles. The first interface tile is in electrical communication with a first array of pins on the integrated circuit die, and the second interface tile is in electrical communication with a second array of pins on the integrated circuit die. At least one dedicated routing resource is formed on the integrated circuit die between the first interface tile and the second interface tile. The at least one dedicated routing resource is configured to couple at least one pin of the first array of pins to at least one pin of the second array of pins.