Selectable Logarithmic/Linear Response Active Pixel Sensor Cell with Reduced Fixed-Pattern-Noise Based on Dynamic Threshold MOS Operation

A selectable logarithmic/linear response active pixel sensor cell with reduced fixed-pattern-noise is proposed. It is composed of four dynamic threshold metal-semiconductor-oxide field-effect transistors (DTMOSs), which have inherently fewer characteristic fluctuations than conventional bulk counterparts. Therefore this proposed active pixel sensor cell is expected to reduce fixed-pattern-noise as compared with that of a device composed of bulk metal-oxide-semiconductor field effect transistors (MOSFETs) without any external noise reduction circuitry particularly in the logarithmic response mode. The effectiveness of the proposed sensor cell is partly experimentally verified using test devices that simulate the readout portion of the proposed sensor cell.