Imaging pixels with improved analog-to-digital circuitry

Abstract

Imagers may include analog-to-digital converter circuitry that produces a digital output code from an analog input voltage. The analog-to-digital converter circuitry may include a series of capacitors including a first set of binary-mapped capacitors. The analog-to-digital converter circuitry may include a second set of one or more capacitors that have capacitances that are less than binary-mapped capacitance values. The digital output code may include bits having respective bit positions within the digital output code. During successive-approximation operations performed by the analog-to-digital converter circuitry, each bit of the digital output code may be produced using a corresponding capacitor. Digital processing circuitry such as an image processor may produce a digital value from the digital output code by multiplying the bits of the digital output code with respective weights determined based on the capacitance of the corresponding capacitors.