A CMOS analog front-end circuit for an FDM-hased ADSL system is presen
ted, The circuit contains all analog functions including AGC amplifier
s, continuous-time band pass filters, Sigma Delta AD/DA converters, an
d digital decimation and interpolation filters, On-chip automatic tuni
ng of the bandpass filters provides more than 300% center frequency ra
nge with 1% frequency accuracy, The higher-order Sigma Delta AD/DA con
verters achieve 12-b data conversion at 1.54 Msamples/s with an oversa
mpling ratio of only 32, The 0.7 mu m CMOS circuit measures 65 mm(2) a
nd consumes 1.9 W from a single 5 V power supply.