Patent ID: 7719583
Filing Date: 2010-05-18
Classification: H04N

Abstract:
1. A method for operating a pixel circuit, comprising: determining an average light intensity value for a set of image data; comparing the determined average light intensity value with a pre-determined threshold; generating a mode selection signal in accordance with the comparing of the determined average light intensity value with a pre-determined threshold, the mode selection signal being a source follower signal when the determined average light intensity value is greater than the pre-determined threshold, the mode selection signal being a common source amplifier signal when the determined average light intensity value is not greater than the pre-determined threshold; receiving the mode selection signal at a selector circuit coupled to a pixel circuit; operating the pixel circuit in a source follower mode when the pixel circuit is in a reset period; operating the pixel circuit in a common source amplifier mode when the pixel circuit is in a read period; connecting, in response to the mode selection signal being a source follower signal, a first voltage source to a drain of a reset transistor of the pixel circuit by the selector circuit connecting the first voltage source to the source column; connecting, in response to the mode selection signal being a source follower signal, the first voltage source to a drain of a sense transistor of the pixel circuit by the selector circuit connecting the first voltage source to the source column; operating the pixel circuit in a common source amplifier mode when the pixel circuit is in a reset period; operating the pixel circuit in a source follower mode when the pixel circuit is in a read period; and connecting, in response to the mode selection signal being a common source amplifier signal, a second voltage source to the readout column.