Importance

Loading Importance Indicators...

Abstract

Digital subscriber modems (8, 15) for use in Asynchronous Digital Subscriber Line (ADSL) communications are disclosed. Each modem includes a digital transceiver function (10, 13) and an analog front end function (10, 11), where the analog front end function (10, 11) is integrated into a single integrated circuit. According to the disclosed embodiments, the analog front end functions (10, 11) each include a transmit and a receive side. The transmit side includes oversampled registers (44C, 44R) and digital filters (46C, 46R) which serve to increase the sample rates of the digital data to be transmitted, so that the analog-to-digital converter (48C, 48R) operates in an oversampled manner, and so that the downstream analog low pass filters (50C, 50R) can be realized with relatively simple, low-order filters. On the receive side, digital filter functions (64C, 64R) are included downstream from the analog-to-digital converters (62C, 62R), to minimize the complexity of the receive-side analog filters (58C, 58R). The remote DSL modem (8) also includes an equalizer function (57) to boost the signal amplitude with increasing frequency, to overcome the effects of line attenuation on the high frequency downstream transmissions.

Loading the Abstract Image...

First Claim