A smart accurate pressure-transducer for high-temperature applications [in oil wells]

This paper describes a high-temperature pressure-transducer interface for resistive Wheatstone bridges. The long-term drift of the smart sensor, i.e., the (pressure) sensor plus its interface electronics, will be determined by the drift of the sensor element only. A three-signal auto-calibration sequence of the interface electronics keeps the transducer interface virtually free of long-term drift. A novel low-drift preamplifier forms an essential element in this system. The high-temperature operation of the transducer interface has been investigated from both an electronic and a packaging point of view. The system has been realized by combining CMOS ASICs with a thick-film packaging technology. The pressure-transducer interface works up to 250-275°C with 15-16 bits accuracy