Method and apparatus for slew rate and impedance compensating buffer circuits
US5898321A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 24, 1997 |
| Grant date | Apr 27, 1999 |
| Priority date | — |
| Expiry date | Mar 24, 2017 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03K17/164
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A method and an apparatus for adjusting the slew rate and impedance of a buffer in an integrated circuitry. In one embodiment, an integrated circuit buffer includes a pre-driver circuit, which includes a slew rate compensation circuit, coupled to a driver circuit, which includes an impedance compensation circuit. The slew rate compensation circuit includes parallel connected p-channel transistors to power and parallel connected n-channel transistors to ground to provide a variable resistance to virtual rails for inverter circuits that are included in the pre-driver circuit. The slew rate compensation circuit is digitally controlled with slew rate control signals. The impedance compensation circuit includes parallel connected p-channel transistors to power and parallel connected n-channel transistors to ground from an output node of the buffer. The parallel connected transistors of the impedance compensation circuit are digitally controlled with impedance control signals. The resistance to power and ground from the respective rails of the pre-driver circuit are controlled with the slew rate control signals to adjust the slew rate of data signals being driven by the buffer. The rails…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.