Impedance matching with sigma delta filter
US6625278B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Aug 24, 1999 |
| Grant date | Sep 23, 2003 |
| Priority date | — |
| Expiry date | Aug 24, 2019 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04M1/76
- WIPO fieldTelecommunications
- WIPO sectorElectrical engineering
Abstract
An AC impedance matching architecture which provides programmable AC impedance matching in a given range using a digital filter to filter a signal fed back from the impedance matched line to generate an AC impedance emulation control signal. The AC impedance emulation control signal is combined with a transmit signal (if desired) and drives a voltage controlled current source, which is in parallel with a reference impedance. A voltage is developed across the reference impedance to drive, e.g., the telephone line. The reference impedance is chosen based on a desired maximum AC impedance. The gain of the digital filter, a first order sigma delta filter in the disclosed embodiment, is chosen based on the desired value of the AC impedance. The transfer function of the digital filter is derived based on a desired AC impedance.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.