Flip-flop with full scan capability
US5668490A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 1, 1996 |
| Grant date | Sep 16, 1997 |
| Priority date | — |
| Expiry date | May 1, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K3/35625
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A flip-flop with scan capability includes a four switches, a master stage, a slave stage and a scan-out logic gate. The flip-flop can operate in a functional mode, and a scan mode and receives a clock signal, a data signal, a scan clock signal and a scan-in signal. The flip-flop enters the functional mode when the clock signal runs free and the scan clock signal is held constant. The first switch receives the data signal and provides the data signal to the master stage for storage during a first part of a clock cycle. During a second part of the clock cycle, the third switch, connected between the master stage and the slave stage, closes, providing the data stored in the master stage to the slave stage and outputted as a q output signal. The flip-flop enters the scan mode when the clock signal is held constant and the scan clock signal runs free. The first switch is controlled to stay open by the constant clock signal. During a first part of a scan clock cycle, the second switch closes, providing the scan-in signal to the master stage. The data stored in the master stage is provided to the fourth switch, connected between the master stage and the scan-out logic gate. During a secon…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.