Patent ID: 8049652

Claim:
An apparatus comprising: a coarse reference ladder providing a plurality of coarse references; a coarse analog-to-digital converter (ADC) configured to receive an input voltage from a sample of an analog input signal, wherein the coarse ADC is configured to perform a first comparison of the input voltage and the plurality of coarse references and output a coarse output; a switch matrix including a plurality of switches, the switch matrix configured to close a switch based on the coarse output, the switch corresponding to a coarse reference; an input line coupled to the switch matrix, wherein the input line is precharged to the input voltage and then settles from the precharged input voltage to a voltage level of the coarse reference; a fine reference ladder providing a plurality of fine references based on the coarse reference, wherein the precharged input line is in between the switch matrix and the fine reference ladder; a fine ADC configured to receive the input voltage and perform a second comparison of the input voltage and the plurality of fine references and output a fine output; and logic configured to output a digital output for the sample of the analog input signal based on the coarse output and the fine output.