The AD1877 is a stereo, 16-bit oversampling ADC based on Sigma Delta () technology intended primarily for digital audio bandwidth applications requiring a single +5 V power supply. Each single-ended channel consists of a fourth-order one-bit noise shaping modulator and a digital decimation filter. An on-chip voltage reference, stable over temperature and time, defines the full-scale range for both channels. Digital output data from both channels are time-multiplexed to a single, flexible serial interface. The AD1877 accepts a 256 x FS or a 384 x FS input clock (FS is the sampling frequency) and operates in both serial port "master" and "slave" modes. In slave mode, all clocks must be externally derived from a common source. Input signals are sampled at 64 x FS onto internally buffered switched-capacitors, eliminating external sample-and-hold amplifiers and minimizing the requirements for antialias filtering at the input. With simplified antialiasing, linear phase can be preserved across the passband. The on-chip single-ended to differential signal converters save the board designer from having to provide them externally. The AD1877's internal differential architecture provides increased dynamic range and excellent power supply rejection characteristics. The AD1877's proprietary fourth-order differential switched-capacitor modulator architecture shapes the onebit comparator's quantization noise out of the audio passband. The high order of the modulator randomizes the modulator output, reducing idle tones in the AD1877 to very low levels. Because its modulator is single-bit, AD1877 is inherently monotonic and has no mechanism for producing differential linearity errors.