Ripple-borrow binary subtraction circuit
US4685079A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Dec 14, 1984 |
| Grant date | Aug 4, 1987 |
| Priority date | — |
| Expiry date | Dec 14, 2004 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F7/503
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A binary subtracter stage for subtracting single bit binary numbers includes a first exclusive OR gate to which the numbers to be subtracted are applied. The output of the exclusive OR gate is connected to one input of a second exclusive OR gate which has a second input connected to a borrow input signal. The output of the second exclusive OR gate provides the difference between the single bit binary numbers. A borrow output signal is generated with the combination of a pass transistor coupled between the borrow input and borrow output terminals and a three state logic circuit which has its output termial connected to the borrow output terminal. The pass transistor is controlled by the output of the first exclusive OR gate and the three state logic circuit is controlled by the single bit binary numbers to be subtracted.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.