FPGA Logic Cell WLUT Chains for Area and Timing Efficiency
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Solution Overview
Problem
Existing Field Programmable Gate Array (FPGA) logic cells are not sufficiently area and timing efficient, nor placement-friendly, limiting their ability to implement complex digital logic circuits effectively.
Innovation Solution
The development of a new integrated circuit design featuring logic cells with enhanced multiplexing capabilities, forming Wide Look-Up Table (WLUT) chains and buddy logic configurations, which allow for more efficient signal routing and function implementation using fewer cells, reducing area occupancy and timing delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If traditional FPGA logic cells are used, then basic logic functions can be implemented, but area efficiency and timing performance are insufficient
Solution Approach 1:
The patent merges multiple LUTs into a single logic cell to form WLUT chains, where adjacent LUTs share common input terminals and are interconnected through multiplexers. This consolidation reduces the total number of separate cells needed, improving area efficiency while maintaining the ability to implement complex logic functions.
Solution Approach 2:
The enhanced logic cell is designed with multiple input terminals and configurable multiplexers that allow a single cell to perform multiple functions. By configuring the multiplexers and interconnections, the same cell structure can implement various logic functions, reducing the need for different specialized cells and improving overall area utilization.
2Productivity
If traditional FPGA logic cells are used, then basic logic functions can be implemented, but timing delays are excessive
Solution Approach 1:
By merging adjacent LUTs into WLUT chains with shared inputs and direct multiplexer interconnections, the patent eliminates the need for signals to traverse through multiple separate cell boundaries and general-purpose routing networks. This reduces the number of routing steps and associated delays, improving timing performance.
Solution Approach 2:
The multiplexers within the WLUT chain act as intermediaries that directly connect LUT outputs to subsequent LUT inputs without requiring external routing. This intermediary structure provides dedicated, low-delay pathways for signal propagation through the chain, reducing overall timing delays compared to traditional routing through general-purpose interconnects.
3Adaptability or versatility
If traditional FPGA logic cells are used, then standard logic functions can be implemented, but placement flexibility is limited
Solution Approach 1:
The patent designs a universal logic cell structure with configurable multiplexers and interconnections that can be programmed to perform various logic functions. This universality allows the same cell type to be placed in different locations and configured for different functions, improving placement flexibility without requiring multiple specialized cell types.
Solution Approach 2:
The logic cell incorporates dynamically configurable elements, including multiplexers that can be programmed through configuration memory cells to establish different signal paths and logic functions. This dynamic reconfigurability allows the cell to adapt to different placement scenarios and logic requirements, enhancing placement flexibility despite the increased internal structure.
Data Source
AI summary
The present invention provides integrated circuits with improved logic cells. In one embodiment, an integrated circuit having a plurality of logic cells (LC) is provided, each LC comprising: a lookup table having a LUT output terminal; and, a first multiplexer; wherein, a first multiplexer input terminal is connected to of a first input terminal of the LC, a second multiplexer input terminal is connected to the LUT output terminal, a multiplexer output terminal is connected to a first output terminal of the LC, and a multiplexer select terminal is connected to a second input terminal of the LC so as to select which of the signals appearing at the first and second multiplexer input terminal to pass through; wherein, by coupling in chain the first input terminal of one LC to the first output terminal of another LC, a WLUT chain is formed.