Signal modulation across capacitors
US5654984A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 3, 1993 |
| Grant date | Aug 5, 1997 |
| Priority date | — |
| Expiry date | Dec 3, 2013 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01F2038/146
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
A method and apparatus for communicating a modulated signal across an isolation barrier using capacitors is provided. The present invention allows low distortion communication of an audio signal across an isolation barrier without the need for a large and bulky isolation transformer. The present invention may be used to provide telephone line isolation for modem applications compliant with governmental regulations. A line interface integrated circuit (IC) may be connected directly to a telephone line and powered by the telephone line. The line interface IC may include a sigma delta modulator to communicate the receive signal across a capacitor over an isolation barrier and a digital-to-analog (D/A) converter to provide an analog transmit signal from a sigma delta bit stream communicated across a capacitor over an isolation barrier. Circuitry on the opposite side of the isolation barrier includes similar components to process the transmit and receive signals.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.