Analogue-to-digital Converter
The circuit that turns the analogue voltage from each photosite into a discrete numerical value.
Measured in
bits
In depth
The converter's bit depth sets how finely the signal is divided, and its own noise sets a floor beneath which sensor performance cannot be recovered. Modern designs place a converter on each column, or on the stacked layer beneath the sensor, which is what makes fast readout and 14- or 16-bit files at high frame rates possible.
Examples in practice
A 14-bit converter divides the signal into 16,384 levels; a 12-bit one into only 4,096.