Low distortion driver employing positive feedback for reducing power loss in output impedance that effectively matches the impedance of driven line
US5856758A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 20, 1996 |
| Grant date | Jan 5, 1999 |
| Priority date | — |
| Expiry date | Nov 20, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04L25/028
- WIPO fieldDigital communication
- WIPO sectorElectrical engineering
Abstract
A line driver with positive feedback reduces the output signal amplitude excursion required for driving a communication line, and enables the driver's output impedance to be synthesized using a reduced component value, thereby achieving a reduction in power loss through the output resistor, while simultaneously matching the effective electrical value of the driver's output impedance to the line. The line driver includes an operational amplifier having differential polarity inputs and an output. An output resistor, whose value is a fraction of the line impedance, is coupled between the amplifier output and an output node coupled to the line. A negative feedback resistor is coupled between the amplifier output and an inverting input. A further resistor is coupled between the amplifier output and a non-inverting input. The further resistor has a value of k*R, where m=(k+1)/(k-1), R is the value of each of input and negative feedback resistors, and m is the ratio of the desired output resistance Rt to the value Ro of the line driver's output resistor.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.