A fourth-order interpolative modulator was designed and fabricated in a 2-µm CMOS technology. As a key building block, a fully-differential folded-cascode operational amplifier has been developed and successfully tested. The main design emphasis is placed on achieving a fast settling behavior. The fully-differential analog modulator operates at the rate of 5.12MHz and provides a signal-to-noise ratio higher than 96dB for 16-bit analog-to-digital conversion.