FPGA configurable logic block with multi-purpose logic/memory circuit
US6150838A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 25, 1999 |
| Grant date | Nov 21, 2000 |
| Priority date | — |
| Expiry date | Feb 25, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K19/17792
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A logic/memory circuit (LMC) utilized in a configurable logic block (CLB) of a programmable logic device (PLD) that implements an eight-input lookup table (LUT) using an array of programmable elements arranged in rows and columns. A decoder is used to read bit values from one column (e.g., sixteen programmable elements) of the array. In one embodiment, a separate read bit line is provided to facilitate faster read operations. A sixteen-to-one multiplexer/demultiplexer circuit is used to pass selected bit values to an output terminal. The array of programmable elements is programmable both from configuration lines during a configuration mode, and by data transmitted on the interconnect resources through the multiplexer/demultiplexer circuit. In one embodiment, the programmable elements of the array are connected in pairs to product term generation circuitry. Product terms generated by the product term circuitry are passed to a macrocell circuit to perform programmable array logic (PAL) logic operations. In another embodiment, a CLB includes four LMCs and a multiplier circuit such that large amounts of logic are locally implemented, thereby avoiding signal delays associated with tran…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.