Some Techniques for Direct Digitization of Transducer Outputs

This application note details circuit techniques which directly digitize the low level outputs of a variety of transducers.
The approaches described are unique in that they do not utilize any DC gain stage. The transducer outputs receive no DC signal conditioning; A/D conversion is directly
performed at low level. The circuits produce a serial data output which may be transmitted over a single wire with the characteristic noise immunity of digital systems. eliminating the traditional DC gain stage, these circuits
furnish a direct, economical way to digitize low level transducer outputs without sacrifi cing performance.
Application Note 7
February 1985

Some Techniques for Direct Digitization of Transducer Outputs
Jim Williams

Almost all transducers produce low level signals. Normally, meaning a 10-bit A/D converter must have an LSB incre-
high accuracy signal conditioning ampliers are used to ment of only 30μV. Performing a 10-bit conversion on a
boost these outputs to levels which can easily drive cables, type K thermocouple monitoring a 0°C to 60°C environment
additional circuitry, or data converters. This practice raises proves even more stringent. The type K thermocouple
the signal processing range well