Common mode early voltage compensation subcircuit for current driver
US5592510A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 29, 1994 |
| Grant date | Jan 7, 1997 |
| Priority date | — |
| Expiry date | Mar 29, 2014 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/029
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
In a driver circuit for a twisted pair cable, a compensator for preventing appreciable common mode current flow into or out of the twisted pair cable in response to the device receiving a wide range of common mode voltage bias levels. A wide range of external bias voltages may be received as a result of variations in the ground node voltages of two coupled devices. The compensator circuit utilizes a feed back loop and monitors the bias voltage received on the twisted pair cable. As the magnitude of the common mode current increases due to external bias voltage variation from a reference bias voltage, the current flow of p-channel transistors, coupled in an arrangement of the present invention, is increased (or decreased, as necessary) so that reduced common mode current flows onto the twisted pair cable. The present invention reduces appreciable common mode current flow through the twisted pair cable from the driver that are due to variations in the external bias voltage between communication devices. The present invention provides high common mode output impedance for the driver circuit by altering the effective common mode common mode early voltage characteristics of the driver c…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.