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Extending Input Voltage Range and Understanding Associated Errors for ADC With I

 

A common input configuration for many analog to digital converters (ADC) uses an internal programmable gain amplifier (PGA) and a resistive attenuator network. This type of converter typically allows several different software configurable input ranges (for example, 0V to 5V, ±5V, and ±10V). These input ranges can be extended to wider input voltages using external resistors. Unfortunately, adding the external resistors will impact gain error, and gain drift. This paper will show how to select external resistor to extend the range, and how to estimate and minimize the errors introduced by the resistors.