Bidirectional Switch Box Routing With Fewer Multiplexers
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Solution Overview
Problem
Existing switch boxes in integrated circuits with programmable logic face issues of significant signal delay and signal edge degradation due to the need for multiple transmission gates and multiplexers, which increase chip area and delay, while also failing to maintain signal amplification effectively.
Innovation Solution
A switch box design utilizing 4-to-1 directional change multiplexers and 1-to-2 directional multiplexers, requiring only 6 setting bits, allowing for bidirectional signal routing with minimal delay and eliminating the need for tristate buffers, by using a direction change multiplexer to manage signal direction changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If transmission gates are used for routing signals, then the chip area is reduced, but signal delay increases and signal edge steepness degrades
Solution Approach 1:
The patent combines the functions of transmission gates and multiplexers into a unified switch box structure. The 1-to-2 multiplexers and 4-to-1 multiplexer work together with transmission gates to achieve both area efficiency and signal integrity by consolidating routing functions that would otherwise require separate components.
Solution Approach 2:
The switch box design provides multi-functional capability through its configurable routing paths. The same hardware structure can route signals in multiple directions (east, west, north, south) and can function as both transmission gates and multiplexers depending on the configuration of setting bits, eliminating the need for dedicated tristate buffers and reducing overall chip area while maintaining signal quality.
2Manufacturing precision
If multiplexers with signal amplification are used, then signal edge steepness is maintained, but chip area increases and signal delay increases
Solution Approach 1:
The patent applies signal amplification selectively rather than universally. The 4-to-1 multiplexer provides signal amplification when needed for complex routing decisions, while the 1-to-2 multiplexers handle simpler routing tasks with minimal amplification. This partial application of amplification maintains signal edge steepness for critical paths while avoiding the area and delay penalties of universal amplification across all routing elements.
3Adaptability or versatility
If tristate buffers are used for bidirectional routing, then signal routing flexibility is improved, but chip area increases and signal delay increases
Solution Approach 1:
The patent inverts the conventional approach by using unidirectional multiplexers configured for bidirectional routing instead of traditional bidirectional tristate buffers. The 1-to-2 multiplexers are configured to route signals in opposite directions through complementary control logic, achieving bidirectional functionality without requiring tristate buffers. This inversion eliminates the area and delay overhead of tristate buffers while maintaining routing flexibility through the programmable nature of the multiplexers.
Data Source
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Figure 3a~3m
AI summary
The present invention aims to provide a switchbox with a small number of multiplexers and setting bits that can both forward a signal in the direction of travel and reverse its direction. This objective is achieved by using switchboxes consisting of directional multiplexers and at least one reversing multiplexer. This allows the signal direction to be changed arbitrarily without significantly increasing the size of the directional multiplexers.