The resolution defines the smallest voltage change that can be measured by the ADC. The resolution of an ADC is determined by the reference input and by the word width. Adding the voltages corresponding to each set bit in 0010 1100, we get:
Each succeeding bit represents half the range of the previous bit. The most significant bit of this word indicates whether the input voltage is greater than half the reference (2.5V, with a 5V reference). Our 8-bit converter represents the analog input as a digital word. The step size of the converter defines the converter’s resolution. This voltage range is divided into 256 values, or steps. Our example 8-bit ADC can convert values from 0V to the reference voltage. The reference voltage is the maximum value that the ADC can convert. It has one output, an 8-bit digital word that represents the input value. This hypothetical part has two inputs: a reference and the signal to be measured. F igure 1 shows a simple voltage-input ADC.
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