The AD7609 is an 18-bit， 8-channel， true differential， 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 analogto-digital converter （ADC）， a flexible digital filter， a 2.5 V reference and reference buffer， and high speed serial and parallel interfaces. The AD7609 operates from a single 5 V supply and can accommodate ±10 V and ±5 V true bipolar differential 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 AD7609 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 AD7609 antialiasing filter has a ?3 dB cutoff frequency of 32 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.