Dual-Mode LUTRAM Reuse for FPGA Configuration Memory
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Solution Overview
Problem
Conventional programmable integrated circuits waste die area and consume excessive leakage power due to unused memory cells, as many LUTRAM and CRAM cells are not fully utilized, leading to inefficiencies in circuit design and operation.
Innovation Solution
Implementing dual-mode memory elements that can operate as both LUTRAM and CRAM cells, allowing unused LUTRAM cells to be reused as CRAM cells, thereby reducing the number of CRAM columns and minimizing waste, with specialized handling of configuration write and readback operations to ensure coexistence and efficient utilization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate LUTRAM and CRAM columns are used in conventional logic blocks, then configuration functionality is provided, but die area is wasted and leakage power is consumed by unused memory cells
Solution Approach 1:
The patent makes LUTRAM cells capable of operating in two modes: as traditional LUTRAM for user data storage and as CRAM for configuration data storage. This multi-functionality allows the same physical memory cells to serve dual purposes, eliminating the need for separate dedicated CRAM columns and thereby reducing die area while maintaining configuration functionality.
2Reliability
If separate LUTRAM and CRAM columns are used in conventional logic blocks, then configuration functionality is provided, but leakage power is consumed by unused memory cells
Solution Approach 1:
By enabling LUTRAM cells to function as CRAM cells, the patent ensures that all memory cells in the logic block are productively utilized. This eliminates idle CRAM columns that would otherwise consume leakage power, thereby reducing overall energy loss while maintaining necessary configuration capabilities.
3Area of stationary object
If LUTRAM cells are reused as CRAM cells, then memory utilization is improved and die area is reduced, but configuration write and readback operations require specialized handling
Solution Approach 1:
The patent implements dynamic mode selection where LUTRAM cells can be configured to operate in either LUTRAM mode or CRAM mode based on operational requirements. This dynamic reconfigurability allows the system to adapt the function of memory cells in real-time, managing the complexity of dual-mode operations through programmable control rather than fixed hardware distinctions.
Data Source
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AI summary
A programmable integrated circuit may include configuration random-access memory (CRAM) cells and lookup table random-access memory (LUTRAM) cells. The programmable integrated circuit may include a CRAM column and at least two LUTRAM columns, a first portion of which is operable as LUTRAM cells and a second portion of which is reused as CRAM cells. Each of the memory cells have a configuration write port and a read port. The configuration write ports of the first portion may be gated, whereas the configuration write ports of the second portion lack gating logic. The read port of the memory cells in the LUTRAM columns may be masked only when the first portion of cells are operated in RAM mode and are currently being accessed.