Shared-Front-End Crosspoint Switch for Low-Capacitance Signal Routing
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Solution Overview
Problem
In integrated circuit (IC) chip designs, signals propagating along long metal wires experience significant propagation delay and distortion due to high RC constants, which conventional repeaters fail to adequately address, introducing additional parasitic capacitance and delay.
Innovation Solution
A cross-point switch is implemented using a plurality of tri-state repeaters coupled to form multiplexers, each sharing a front-end module to reduce delay through input capacitance, with each tri-state repeater comprising up-drive, down-drive, keeper, and enable modules operating in four states to manage signal transitions and impedance effectively.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional repeaters are used to amplify signals and reduce propagation delay, then signal distortion is reduced, but parasitic capacitance increases causing additional propagation delay
Solution Approach 1:
The patent combines the repeater function with the crosspoint switch function into a single integrated structure. The repeater is formed by transistors at the crosspoint of row and column wire sets, eliminating the need for separate repeater components and reducing parasitic capacitance while maintaining signal amplification and delay reduction capabilities.
Solution Approach 2:
The crosspoint transistors perform multiple functions simultaneously: they act as both switch elements for routing signals and as repeaters for signal amplification. This multi-functionality reduces the overall component count and parasitic capacitance in the system.
2Power
If large output drive transistors are used to drive long metal wires, then signal strength is improved, but device area and parasitic capacitance increase
Solution Approach 1:
The patent segments the signal path into row wire sets and column wire sets that intersect at crosspoints. This segmentation allows signals to be driven along shorter individual wire segments rather than requiring single large transistors to drive entire long wires, reducing the area and parasitic capacitance of individual drive transistors.
Solution Approach 2:
The crosspoint transistors act as intermediary elements that receive signals from row wires and drive column wires (or vice versa). This intermediary structure breaks up long wire drives into shorter segments, allowing smaller transistors to effectively drive the wires while maintaining signal strength.
Data Source
AI summary
A cross point switch, in accordance with one embodiment, includes a plurality of tri-state repeaters coupled to form a plurality of multiplexers. Each set of corresponding tri-state repeaters in the plurality of multiplexers share a front end module such that delay through the cross point switch due to input capacitance is reduced as compared to conventional cross point switches.