ACTIVE PIXEL SENSOR FOR DIGITAL IMAGING

摘要

An active pixel sensor for digital imaging comprises a detector, a readout circuit, and a resistive load. The detector is integrated with the readout circuit and the readout circuit has a plurality of amorphous silicon based thin-film transistors (TFTs). The readout circuit is embedded under the detector to provide a high fill factor. A signal charge is accumulated on a pixel capacitance during an integration mode and is transferred to an external electronics for data acquisition via the readout circuit during a readout mode. An output current from the readout circuit is converted to a voltage through the resistive load. The resistive load may be a thin-film transistor operated in a saturation regime and having a width larger than a length in size. The active pixel sensor amplifies an on-pixel sensor input signal to improve a noise immunity of sensitive sensor input signals to external noise sources and its linearity together with a fast pixel readout time.