A low-power comparator for a single-ramp ADC in an imager array

摘要

A comparator with an input stage that selectively powers up an output stage provides an electronic device with a comparator that operates at low power. In an embodiment, an input stage produces a near decision and a true decision, where the near decision is provided to power up an output stage for the comparator to provide an output representative of the true decision. With a ramping reference voltage, the output stage can be configured to be powered up only a fraction of the ramp time of the reference voltage, reducing the power consumption of the output stage. In an embodiment, the electronic device is an imaging device having an array of pixels, where each column of the array is associated with a comparator having an input stage to produce a near decision and a true decision and a single ramp generator to provide a ramping reference signal to each comparator.