The AD743 is an ultralow noise precision, FET input, monolithic operational amplifier. It offers a combination of the ultralow voltage noise generally associated with bipolar input op amps and the very low input current of a FET-input device. Furthermore, the AD743 does not exhibit an output phase reversal when the negative common-mode voltage limit is exceeded. The AD743's guaranteed, maximum input voltage noise of 4.0nV/Hz at 10 KHz is unsurpassed for a FET-input monolithic op amp, as is the maximum 1.0 V p-p, 0.1 Hz to 10 Hz noise. The AD743 also has excellent dc performance with 250 pA maximum input bias current and 0.5 mV maximum offset voltage. The AD743 is specifically designed for use as a preamp in capacitive sensors, such as ceramic hydrophones. It is available in five performance grades. The AD743J is rated over the commercial temperature range of 0C to 70C. The AD743 is available in 8-Lead plastic mini-DIP, and 16-pin SOIC.