Title :
A fourth-order bandpass delta-sigma modulator with reduced numbers of op amps
Author_Institution :
Dept. of Electr. & Comput. Eng., Illinois Univ., Urbana, IL, USA
fDate :
12/1/1995 12:00:00 AM
Abstract :
A switched-capacitor quadrature demodulation technique, which is insensitive to first-order errors resulting from 90° phase inaccuracy and path mismatch, is demonstrated to shift a band-pass spectrum directly to dc. A sampling rate of four times the passband center frequency facilitates the quadrature demodulation and removes the 90° phase error. Furthermore, the path-mismatch error is canceled using the same signal path repeatedly, thereby reducing the number of op amps. A fourth-order band-pass Δ-Σ modulator, integrated in an area of 1 mm2 using 2-μm CMOS, consumes 0.8 mW with a single 3.3-V supply and exhibits an SNR of 56 dB within a 30-kHz bandwidth
Keywords :
CMOS integrated circuits; sigma-delta modulation; switched capacitor networks; 0.8 mW; 2 micron; 3.3 V; 30 kHz; CMOS; SNR; band-pass spectrum; fourth-order bandpass delta-sigma modulator; passband center frequency; path-mismatch error; phase error; sampling rate; switched-capacitor quadrature demodulation technique; Band pass filters; Baseband; Delta modulation; Demodulation; Digital modulation; Filtering; Image converters; Image sampling; Operational amplifiers; Radio frequency;
Journal_Title :
Solid-State Circuits, IEEE Journal of
