The most direct way is to measure the output waveform of the MAX9271. However, many of our customers do not have oscilloscopes capable of measuring high speed signals. The most common oscilloscopes with bandwidths ranging from several dozen to several hundred MHz can roughly determine if the MAX9271 is operating normally: Measure the common mode voltage at the MAX9271 output (before the AC coupling capacitor). A normal operating common mode voltage ranges between 1.1V ~ 1.56V, with a typical value of 1.4V. If the measured common mode voltage is under several hundred millivolts, you can assume the IC is not operating properly.