Orthogonal VLSI Layouts for Fully Connected Multi-Stage Networks
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Solution Overview
Problem
Existing VLSI layouts of multi-stage interconnection networks like Benes and butterfly fat tree networks are inefficient, leading to large area requirements, increased power consumption, longer wires, and higher latency in integrated circuits, making them impractical for implementation on semiconductor chips.
Innovation Solution
The development of VLSI layouts for generalized multi-stage networks that utilize only horizontal and vertical links, employing shuffle exchange connections and a hypercube arrangement to reduce crosspoints, signal latency, and power consumption, while maintaining full connectivity and fast compilation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If traditional multi-stage interconnection networks (Benes, butterfly fat tree) are implemented in VLSI layouts, then full connectivity and network functionality are achieved, but the area requirement becomes excessively large
Solution Approach 1:
The patent transforms the traditional two-dimensional grid-based VLSI layout into a three-dimensional stacked architecture. Multiple network stages are arranged in vertical layers rather than horizontal expansion, enabling full connectivity without proportional area increase. The vertical dimension provides additional routing paths and reduces wire length while maintaining O(N log N) crosspoint complexity.
Solution Approach 2:
The patent implements a hierarchical nesting structure where smaller functional units (switches, crosspoints) are organized into modular building blocks that are then nested into larger network stages. This nested organization allows efficient space utilization and systematic scaling while maintaining full connectivity properties.
2Adaptability or versatility
If traditional VLSI layouts are used for multi-stage networks, then network connectivity is maintained, but power consumption increases due to longer signal paths
Solution Approach 1:
By stacking network stages vertically, the patent significantly reduces the horizontal distance signals must travel. The vertical interconnects provide direct short paths between stages, eliminating the need for long horizontal wire routes through the chip. This dimensional reorganization reduces signal path length and associated power consumption while preserving full connectivity.
3Adaptability or versatility
If traditional VLSI layouts are used for multi-stage networks, then network functionality is achieved, but signal latency increases due to longer routing paths
Solution Approach 1:
The vertical stacking architecture provides direct short-circuit paths between network stages through vertical interconnects. Signals can traverse multiple stages by moving vertically rather than horizontally across the chip, dramatically reducing propagation delay and signal latency while maintaining full network functionality.
4Use of energy by stationary object
If crosspoint reduction is achieved through network optimization, then power consumption and area are reduced, but implementation complexity increases
Solution Approach 1:
The patent segments the multi-stage network into modular functional blocks, each containing a manageable number of crosspoints. This segmentation allows systematic optimization of crosspoint distribution across stages, reducing total crosspoint count while maintaining connectivity. The modular structure also simplifies implementation by breaking down complex routing logic into repeatable units.
Solution Approach 2:
The patent optimizes network parameters such as the number of stages, crosspoints per stage, and interconnect topology to achieve the minimal crosspoint configuration that still provides full connectivity. By carefully tuning these parameters and using vertical stacking to reduce routing overhead, the implementation becomes more efficient without excessive complexity.
Data Source
AI summary
In accordance with the invention, VLSI layouts of generalized multi-stage networks for broadcast, unicast and multicast connections are presented using only horizontal and vertical links. The VLSI layouts employ shuffle exchange links where outlet links of cross links from switches in a stage in one sub-integrated circuit block are connected to inlet links of switches in the succeeding stage in another sub-integrated circuit block so that said cross links are either vertical links or horizontal and vice versa. In one embodiment the sub-integrated circuit blocks are arranged in a hypercube arrangement in a two-dimensional plane. The VLSI layouts exploit the benefits of significantly lower cross points, lower signal latency, lower power and full connectivity with significantly fast compilation.The VLSI layouts presented are applicable to generalized multi-stage networks V(N1, N2, d, s), generalized folded multi-stage networks Vfold(N1, N2, d, s), generalized butterfly fat tree networks Vbft(N1, N2, d, s), generalized multi-link multi-stage networks Vmlink(N1, N2, d, s), generalized folded multi-link multi-stage networks Vfold-mlink(N1, N2, d, s), generalized multi-link butterfly fat tree networks Vmlink-bft(N1, N2, d, s), and generalized hypercube networks Vhcube(N1, N2, d, s) for s=1, 2, 3 or any number in general. The embodiments of VLSI layouts are useful in wide target applications such as FPGAs, CPLDs, pSoCs, ASIC placement and route tools, networking applications, parallel & distributed computing, and reconfigurable computing.