A -55 to + 200°C 12-Bit Analog-to-Digital Converter

This paper describes the design of a 12-bit successive-approximation hybrid analog-to-digital (A/D) converter that is specified to operate over a temperature range of -55°C to + 200°C. This is an important development, especially for the oil well logging industry, since it is now possible to digitize the signal output from a transducer while it is downhole and thereby make the transmitted digital signal less susceptible to noise and interference. Details of the design and construction of the device as well as 1000-h life test data are presented.