Contents1 Introduction....22 Factors Affecting ADC Gain: When is Gain Calibration Necessary?.....32.1 Input Circuitry..32.2 PGA Setting.....32.3 Decimation Ratio.....42.4 Reference Voltage...42.5 What Doesn’t Affect the ADC Gain?.52.6 When should Gain Calibration be Performed?53 Self-Gain Calibration Command64 System Gain Calibration Command.75 Software Gain Calibration...86 Adjusting ADC Gain......97 Extending the ADC Input Range.....108 Recommendations.....11References.....12FiguresFigure 1. ADC Gain Calibration after Self-Gain Calibration versus PGA Gain.3Figure 2. ADC Normalized Gain Temperature Coefficient versus PGA Gain...5