In a typical sensor-signal chain, what is the recommended order of stages from sensor to ADC?

• A. Sensor, location of offset/scale calibration then signal conditioning (amplification, filtering, impedance matching) then ADC.
• B. Sensor, ADC, then signal conditioning.
• C. Sensor, calibration after ADC.
• D. Sensor, ADC only.

Answer: (A)

The main idea is to correct the sensor’s nonidealities before any analog processing so the signal entering the conditioning stage is already true to the physical quantity being measured. In practice, you first account for the sensor’s offset and scale (gain) errors, so the sensor’s output reflects the actual quantity with the correct zero and full-scale values. Once that baseline is established, you apply signal conditioning—amplification to make the signal span the ADC’s optimal input range, impedance matching to prevent loading, and filtering to remove noise and unwanted frequencies. With the signal properly calibrated first, the conditioning stage can operate on a correctly referenced signal, preserving accuracy and maximizing the ADC’s effective resolution.

If you were to digitize first and then calibrate, you’d be locking in the sensor’s offset and gain errors into the data stream, potentially wasting dynamic range and making later corrections less effective because you’ve already suffered from noise and limited resolution before conditioning. Calibrating after digitization or after the ADC can still help, but it cannot correct the analog issues that happen before digitization and can reduce overall measurement quality.

So, calibrate the sensor’s offset and scale first, then condition the signal, and finally convert with the ADC.