MIXED LINEAR/SQUARE-ROOT ENCODED SINGLE SLOPE RAMP PROVIDES A FAST, LOW NOISE ANALOG TO DIGITAL CONVERTER WITH VERY HIGH LINEARITY FOR FOCAL PLANE ARRAYS

摘要

An analog-to-digital converter (ADC) converts pixel voltages from a CMOS image into a digital output. A voltage ramp generator generates a voltage ramp that has a linear first portion and a non-linear second portion. A digital output generator generates a digital output based on the voltage ramp, the pixel voltages, and comparator output from an array of comparators that compare the voltage ramp to the pixel voltages. A return lookup table linearizes the digital output values.