Excitation Tracking
Analog-to-digital conversion techniques use the sensor excitation voltage as the reference voltage for the converter digitizing process. Applying ratiometric digitizing eliminates output errors caused by fluctuations in bridge excitation power by scaling ADC conversion output directly against excitation supply level. When excitation voltage drifts, sensor output voltage and ADC reference voltage scale by identical proportional amounts.
Industrial pressure transducers and load cell digitizers use this technique to maintain calibration stability without absolute voltage references.
Drift Cancellation
Systematic cancelation occurs because output digital code represents the exact ratio of input voltage to reference voltage. Fluctuations in bridge supply cancel mathematically inside the converter ratiometric architecture. Precision voltage references are unnecessary for excitation supplies when ratiometric conversion is implemented correctly.
Conversion Topology
Differential reference inputs on delta-sigma converters accept direct connection from sensor power rails. Filtering on reference inputs must match signal channel filtering to prevent high-frequency supply ripple from introducing phase mismatched errors. Balanced RC filtering prevents excitation noise from degrading converter dynamic range.
Scaling Limit
Applicability stops when sensor output mechanisms possess non-ratiometric operational dependencies. Active internal sensor electronics powered by independent regulated rails break ratiometric relationships. Ratiometric digitizing maintains measurement stability within zero point zero one percent despite five percent excitation voltage shifts.
