AN2719

Design rules for minimizing errors

17/22

4

Design rules for minimizing errors

ADC precision can only be significantly improved if external influences on the measurement

are minimized. Therefore any precision improvement method also includes rules for correct

design.

Main design rules for minimizing design errors:

●

Grounding of analog/digital power:

–

star topology

●

–

RC, LC filtering

–

avoid noise from noisy digital power

●

–

reference voltage source precision and stability matched to application precision

requirements and ADC capability

–

reference voltage source value and precision in line with the expected measured

range

●

Source impedance vs. input impedance knowledge:

–

use input buffers for measured signal (if source impedance is too high)

–

impedance in relation with required conversion speed

●

External preamplifier usage:

–

for low (and also high) level signals

–

amplifier speed and precision properties

–

amplifier dependency on frequency

●

Select appropriate ADC mode, speed, trigger

●

Software methods: averaging, FFT, …