On-chip broadband tuner design for cable modem and digital CATV

In this paper, a new low-IF architecture for an on-chip implementation of a cable modem receiver is presented. In this receiver, a low power, area efficient digital filter is used to achieve 60dB adjacent channel rejection. A new adaptive analog-digital image-reject technique is also used, which improves the image-rejection ratio to 57dB. Therefore, high-Q, off-chip, SAW filters are not required. Simulations show that a signal-to-interference ratio of 34dB is achieved for a 256QAM transmitted signal.