The AD1879 is a two-channel, 18-bit oversampling ADC based on technology and intended primarily for digital audio applications. The AD1878 is identical to the 18-bit AD1879 except that it outputs 16-bit data words. Statements in this data sheet should be read as applying to both parts unless otherwise noted. Each input channel of these ADCs is fully differential. Each data conversion channel consists of a fifth order one-bit noise shaping modulator and a digital decimation filter. An on-chip voltage reference provides a voltage source to both channels stable over temperature and time. Digital output data from both channels is time-multiplexed to a single, flexible serial interface. The AD1878/AD1879 accepts a 256 x FS input master clock. Input signals are sampled at 64 x FS on 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 AD1878/AD1879's proprietary fifth-order differential switched-capacitor modulator architecture shapes the one-bit comparator's quantization noise out of the audio passband. The high order of the modulator randomizes the modulator output, reducing idle tones in the AD1878/AD1879 to very low levels. The AD1878/AD1879's differential architecture provides increased dynamic range and excellent common-mode rejection characteristics. Because its modulator is single-bit, AD1878/ AD1879 is inherently monotonic and has no mechanism for producing differential linearity errors. The digital decimation filters are single-stage, 4095-tap finite impulse response filters for filtering the modulator's high frequency quantization noise and reducing the 64 x FS single-bit output data rate to a FS word rate. They provide linear