Mirrored FPGA Interconnect Layout for Shorter Critical Paths
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Solution Overview
Problem
There is a need to improve programmable integrated circuits to increase the types of user designs that can be implemented, with existing FPGA architectures limited by wiring delays and inefficiencies in interconnect paths.
Innovation Solution
The design includes a programmable integrated circuit with horizontally arranged columns of interconnect and logic blocks, where programmable interconnect blocks are strategically positioned to shorten single connections and reduce wiring delays by keeping them within interconnect columns, thereby improving performance by utilizing predominantly shorter connections for critical timing paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If interconnect lines are arranged in traditional FPGA architectures, then logic functions can be implemented, but wiring delays are excessive and performance is limited
Solution Approach 1:
The interconnect structure is segmented into dedicated interconnect columns that are physically separated from logic columns. This segmentation allows interconnect lines to be organized in dedicated pathways, reducing cross-interference and shortening connection lengths between adjacent interconnect blocks, thereby reducing wiring delays without significantly increasing overall device complexity.
Solution Approach 2:
The patent introduces a new spatial dimension by arranging interconnect columns and logic columns in an alternating horizontal sequence rather than traditional vertical or mixed layouts. This dimensional reorganization creates shorter horizontal paths for critical timing connections while maintaining the necessary vertical interconnect capability, effectively reducing wiring delays for time-critical paths.
2Adaptability or versatility
If interconnect lines are lengthened to connect distant logic blocks, then more logic functions can be implemented, but wiring delays increase and performance decreases
Solution Approach 1:
Dedicated interconnect columns act as intermediary structures between logic columns. These intermediary interconnect columns provide multiple intermediate connection points and routing options, allowing signals to reach distant logic blocks through a series of shorter segments rather than one long path, thereby maintaining signal integrity and speed while enabling complex logic implementations.
Solution Approach 2:
Long interconnect paths are segmented into multiple shorter segments through the introduction of intermediate interconnect columns. Each segment connects adjacent columns, and the cumulative effect provides long-range connectivity while each individual segment maintains short transmission distance, preserving signal speed and reducing delays.
3Speed
If traditional interconnect arrangements are used, then device layout is simple, but critical timing paths have excessive wiring delays
Solution Approach 1:
The patent employs an asymmetric alternating arrangement where interconnect columns and logic columns are horizontally interleaved in a non-uniform pattern optimized for critical timing paths. This asymmetric layout prioritizes short connection lengths for time-critical signals while maintaining overall structural regularity that limits fabrication complexity.
Solution Approach 2:
Different regions of the device utilize the alternating column arrangement with varying densities and configurations tailored to local timing requirements. Critical timing paths benefit from densely packed alternating columns for maximum shortening, while less critical areas can use more relaxed spacing, optimizing performance without uniformly increasing device complexity.
Data Source
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AI summary
A programmable integrated circuit (IC) with a mirrored interconnect structure includes a plurality of arrangements (102, 104), which are horizontally arranged. Each arrangement includes a first logic column (106), a first interconnect column (108), a second interconnect column (110), and a second logic column (112), horizontally arranged in that order within the arrangement. Each interconnect column includes programmable interconnect blocks (PIBs 130-144, 188-196, 199), and each of the first and second logic columns includes programmable logic blocks (114-128, 164-171 ). Each programmable interconnect block provides a plurality of first input (174) and output (172) ports at one side. Each programmable logic block provides second input (156) and output (158) ports at one side. The first ports and the one side of each of the programmable interconnect blocks in the first interconnect column (108) physically mirror the first ports and the one side of each programmable interconnect block in the second interconnect column (110). The first ports (172, 174) of the programmable interconnect blocks in the first interconnect column (108) are coupled to the second ports (156, 158, 182, 184, 186, 190, 194) of the programmable logic blocks in the first logic column. The first ports of the programmable interconnect blocks in the second interconnect column (110) are coupled to the second ports (160-62, 176-180, 198) of the programmable logic blocks in the second logic column.