Universal serial bus (USB) driver circuit, system, and method
US7595674B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Apr 25, 2006 |
| Grant date | Sep 29, 2009 |
| Priority date | — |
| Expiry date | May 10, 2026 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/0272
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A driver circuit, system, and method is provided. The driver circuit includes a plurality of delay cells or circuits, each comprising a set of flip-flop circuits coupled in series to produce a staged set of outputs onto an output port of the driver circuit. The staged outputs are sequentially applied to the output port at a time depending on the number of flip-flop circuits within each stage. The number of such circuits can be programmably modified so that the slew rate output of the driver circuit can be programmably changed. The driver circuit can be a low speed driver circuit clocked by a low speed clocking signal of, for example, 1.5 MHz, with the slew rate derived by a clocking signal of, for example, 480 MHz. The higher speed clocking signal clocks the flip-flop circuits, yet the output is staged so that the low speed driver circuit transitions between logic states using the higher speed clock, but at a must slower edge rate. Therefore, the driver circuit, system, and method avoids passive electrical components and the PVT fluctuations associated therewith.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.