The width of a given output code (code width) is the range of analog input voltages between two adjacent transition points of an Analog-to-Digital Converter (ADC) digital output code. The code widths are referenced to the weight of 1 Least Significant Bit (LSB), which is defined by the resolution of the converter and the analog reference voltage (VREF). For example, 1 LSB = VREF/2n, where n is the number of bits of resolution. For example, if a 4.096 V reference is used with a 12-bit ADC, 1 LSB will have a weight of 4.096 V/212, or 1 mV. All codes will have a width of 1 LSB for an ideal ADC (i.e, zero offset error, zero gain error, and zero DNL, LNL errors). The transfer function of an ideal 3-bit ADC figure below shows the transition points and code width between adjacent points.
ADC Code Width