Method and apparatus for digital to analog conversion with distortion calibration
US6501405B1 · kind B1 · utility
Assignee
Inventors
Key dates
| Filing date | Jun 13, 2001 |
| Grant date | Dec 31, 2002 |
| Priority date | — |
| Expiry date | Jun 13, 2021 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M3/50
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An apparatus and method is disclosed for minimizing in band distortion in the transmit path of an XDSL modem. The transmit path of an XDSL modem introduces various non-linearities into transmissions in both the frequency and time domains. The current invention provides a means for both determining and correcting for distortion in the time domain. In an embodiment of the invention the apparatus may include a calibrator which may be implemented using the existing analog-to-digital (ADC) conversion and demodulation capabilities on the receive path of the modem or alternately, a dedicated module. During a calibration phase a training signal is injected digitally into the digital-to-analog converter of the transmit path. The analog portion of the transmit path is coupled to a calibrator which measures the corresponding analog response. The correlation between input and response is stored in an analog model. During subsequent training and run-time phases of modem operation an oversampled digital input stream is subject to digital Delta Sigma Modulation (&Dgr;&Sgr;M) with the analog model injected into the feedback path from the quantizer. The injection of the analog model into the feedba…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.