A 13 bit ISDN-band oversampled ADC using two-stage third order noise shaping

A 13-bit 80-kHz baseband analog-to-digital converter suitable for use in applications such as the ISDN U-interface is described. Two-stage third-order noise shaping permits the use of asampling frequency of only 2.56 MHz. The circuit has been implemented using conventional single-ended switched-capacitor techniques in a 1.5-mum CMOS process