ADCdrift

ADCdrift refers to the gradual change over time in the output of an analog‑to‑digital converter (ADC) when the input voltage remains constant. Although modern ADCs are calibrated at production, long‑term variations in components, temperature, aging of circuitry, and power‑supply fluctuations can alter their transfer functions. This leads to a systematic error that can be expressed as a change in offset, gain, or both. For many precision measurement systems, ADC drift manifests as a slow drift of digitised zero‑input values or a deviation from known reference voltages.

Typical causes include temperature‑coefficient mismatch between input amplifiers and ADC input front ends, supply‑voltage sag, MOSFET threshold shifts in embedded ADC architectures, and degradation of internal reference sources. In high‑resolution converters, even a microvolt‑level drift can compromise the measurement accuracy over periods ranging from hours to months. Drift can also be exacerbated by electrostatic discharge or mechanical stress on the printed circuit board.

Detecting ADC drift generally involves periodic comparison of output values against known reference voltages or zero‑input conditions. Automated test routines can log the offset and slope over time and compare them against specified tolerances. Some systems implement on‑chip calibration or use external reference generators to re‑calibrate during idle periods.

Mitigation strategies span design choices and operational practices. Selecting ADCs with low temperature coefficients, employing external precision references, and stabilising the supply rails help reduce drift at the source. In software, differential measurement, averaging, and applying drift compensation curves can correct residual errors. In critical applications, self‑calibration routines that periodically internally recalibrate the ADC using built‑in reference sources are common. Proper PCB layout, shielding, and thermal management also significantly diminish drift sources, ensuring consistent ADC performance over its operational life.