Multi-bit voltage-to-delay conversion in data converter circuitry

Abstract

An analog-to-digital converter circuit incorporating includes a multi-bit input buffer having a differential input and configured to generate, at a plurality of differential outputs, a plurality of residues of a differential input sample relative to a corresponding plurality of zero-crossing references. Chopping stages chop the residues, for example with a pseudo-random binary sequence. The circuit further includes zero-crossing comparators, each with differential inputs coupled to receive one of the chopped residues. The zero-crossing comparators are in an ordered sequence of zone thresholds within the input range of the circuit. Folding logic circuitry has inputs coupled to outputs of the comparators, and outputs a delay domain signal indicating a magnitude of the one of the residues relative to a nearest zone threshold. Digital stage circuitry generates a digital output word representing the received input sample responsive to the comparator outputs and the delay domain signal.