Patent ID: 7397410

Claim:
A conversion circuit comprising: (a) a coarse-resolution quantization circuit including i. a resistor string including a plurality of resistors and a plurality of tap points between the various resistors, and ii. a plurality of coarse-resolution comparators, each coarse-resolution comparator having a first input coupled to receive an input voltage and a second input coupled to a corresponding coarse-resolution tap point, each coarse-resolution comparator being operable during a first phase to produce a first logic level only if the input voltage exceeds a voltage of the coarse-resolution tap point coupled to the second input of that coarse-resolution comparator; and (b) a fine-resolution quantization circuit including i. a plurality of fine-resolution comparators each having a first input coupled to receive the input voltage, each fine-resolution comparator being operable during a second phase to produce a fine-resolution output logic level indicative of whether the input voltage exceeds a voltage of a tap point coupled to a second input of that fine-resolution comparator, and ii. a control circuit operative to selectively couple the second input of each fine-resolution comparator to a corresponding tap point of a group of tap points located immediately below a coarse-resolution tap point coupled to a highest coarse-resolution comparator producing the first logic level, the output logic levels of the fine-resolution comparators and the coarse-resolution comparators up to and including the highest coarse-resolution comparator producing the first logic level representing a thermometer code representation of a quantized value of the input voltage.