Image sensor with improved readout circuit

摘要

An image sensor has an array of pixels (10). Each column has a first (16) and a second (20) column line connected to a read-reset amplifier/comparator (22) which acts in a first mode as a unity gain buffer amplifier to reset the pixels (10) via the first lines (16), and in a second mode acts as a comparator and AD converter to produce digitised reset and signal values. The reset and signal values are read out a line at a time in interleaved fashion. Reset values are stored in a memory (26) and subsequently subtracted from the corresponding signal values. The arrangement reduces both fixed pattern and kT/C noise. <IMAGE>