Sensor Front End

Op-amps are common in sensor front ends. They amplify small voltages, buffer high-impedance signals, add bias, build filters, or convert current into voltage.

They are also easy to misuse. On a schematic, an op-amp looks like a simple triangle, and the formula often looks simple:

output = input * gain

In real circuits, an op-amp is not an ideal amplifier that works at any voltage, frequency, and load. It has input range, output range, speed, accuracy, noise, power, and stability limits. Once one of those limits is hit, the ADC value seen by firmware may saturate, slow down, drift, oscillate, or carry strange noise.