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 4.0 nV/(root)Hz at 10 kHz is unsurpassed for a FET-input monolithic op amp, as is the maximum 1.0 µV p-p, 0.1 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 and AD743K are rated over the commercial temperature range of 0°C to +70°C. The AD743A and AD743B are rated over the industrial temperature range of -40°C to +85°C. The AD743S is rated over the military temperature range of -55°C to +125°C and is available processed to MIL-STD-883B, Rev. C.The AD743 is available in 8-pin plastic mini-DIP, 8-pin cerdip, 16-pin SOIC, or in chip form.