An AFE is an analog front end signal chain that accepts analog inputs and digitizes them for processing or storage for later use. The AFE diagram above shows the basic building block components; op amp, ADC, voltage reference, data isolator, and isolated power. External sensors provide the signals to the AFE’s input and have a voltage with a range of -10 V to +10 V, or 0 V to +10 V or a 4-20 mA current loop.