Tx line driver with common mode idle state and selectable slew rates
US6870390B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Sep 11, 2003 |
| Grant date | Mar 22, 2005 |
| Priority date | — |
| Expiry date | Oct 20, 2023 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/0292
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A transmit line driver with selectable slew rates and a common mode idle state comprises a capacitor array of selectable capacitors coupled between a line driver and a pre-driver wherein a slew rate may be selected by the selectable capacitors. A common mode idle state is provided by coupling a selectable switch (MOSFET in the described embodiment) to a mirror device that provides a bias current to the pre-driver wherein, when the bias current is removed by the switch, the pre-driver produces an output signal that is equal to the supply voltage for the circuit. Accordingly, a differential pair of the line driver are both biased on and provide a common mode idle state. The common mode idle state is equal to one half of an output signal magnitude for a logic one.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.