Reference pre-charging for two-step subranging ADC architecture

摘要

A coarse reference ladder provides a plurality of coarse references. A coarse ADC receives an input voltage. The coarse ADC performs a first comparison of the input voltage and the plurality of coarse references and outputs a coarse output. A switch matrix is configured to close a switch based on the coarse output. An input line corresponding to a coarse reference is coupled to the switch matrix. The input line is precharged to the input voltage. The input line settles from the precharged input voltage to the coarse reference. A fine reference ladder provides a plurality of fine references based on the coarse reference. A fine ADC receives the input voltage and performs a second comparison of the input voltage and the plurality of fine references and outputs a fine output. Logic outputs a digital output for the input voltage based on the coarse output and the fine output.