Low noise tri-state output buffer
US5568062A · kind A · utility
Inventor
Key dates
| Filing date | Jul 14, 1995 |
| Grant date | Oct 22, 1996 |
| Priority date | — |
| Expiry date | Jul 14, 2015 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K19/09429
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A buffer circuit includes a pair of pull-up output transistors and a pair of pull-down output transistors driving an output line. Each output transistor is driven by its own tristate input translator, all connected to an input terminal of the circuit. Two of the translators are tristated by control signals received as feedback from the output line to turn off one of the pull-up transistors when the output exceeds the high logic level transition voltage (2.2 V) and to turn off one of the pull-down transistors when the output drops below the low logic level transition voltage (0.8 V). This not only prevents ground bounce or overshoot of the output, but also avoids larger current flow or power dissipation from pull-up and pull-down transistors being simultaneously partially on during a transition. Because the output transistors are driven directly by the input translators, throughput speed is improved, while ramp rate of the translator outputs driving the output transistors can remain slow to reject input noise spikes and avoid generation of output noise.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.