Programmable logic device with carry look-ahead
US6359468B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Mar 2, 2000 |
| Grant date | Mar 19, 2002 |
| Priority date | — |
| Expiry date | Mar 2, 2020 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K19/17792
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A programmable logic device is adapted to predict carry values in long-chain-carry logic configurations. In the most preferred embodiment, which functions in any long-carry-chain logic configuration, each logic region calculates a result for both values of the carry-in signal to that region, and when a carry signal for the group to which the region belongs reaches the region, the correct result in each region, and thence the correct carry-out for that group, are calculated and propagated. The carry-out terminal of one group is arranged to be adjacent to the carry-in terminal of the next group, to enhance carry propagation speed. In another embodiment, each region looks back two regions to predict the carry-in. In two additional embodiments, logic is provided to mathematically calculate the carry values.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.