The AD7608 is an 18-bit， 8-channel simultaneous sampling， analog-to-digital data acquisition system （DAS）。 The part contains analog input clamp protection， a second-order antialiasing filter， a track-and-hold amplifier， an 18-bit charge redistribution successive approximation analog-to-digital converter （ADC）， a flexible digital filter， a 2.5 V reference and reference buffer， and high speed serial and parallel interfaces. The AD7608 operates from a single 5 V supply and can accommodate ±10 V and ±5 V true bipolar input signals while sampling at throughput rates up to 200 kSPS for all channels. The input clamp protection circuitry can tolerate voltages up to ±16.5 V. The AD7608 has 1 M? analog input impedance regardless of sampling frequency. The single supply operation， on-chip filtering， and high input impedance eliminate the need for driver op amps and external bipolar supplies. The AD7608 antialiasing filter has a 3 dB cutoff frequency of 22 kHz and provides 40 dB antialias rejection when sampling at 200 kSPS. The flexible digital filter is pin driven， yields improvements in SNR， and reduces the 3 dB bandwidth