| 摘要 |
A high sensitivity active pixel (200) for use in MOS image sensor circuits allows digital MOS fabrication processes to be used in implementing a pixel circuit having greater sensitivity (allowing increased frame rate) and greater noise immunity that certain prior art pixels. The novel pixel (200) features a source follower configured amplifier (M21), such as a single MOS FET, coupled between a photodetector (PD20) and a storage capacitor (C2). A light-generated signal from the photodetector (PD20) is used to control the charge placed in the storage capacitor (C2) in order to develop a capture voltage. In a particular embodiment, an n-channel source follower and a p-channel output stage are combined in the pixel to make the overall transfer function of the pixel more linear and distortion free. In particular, the pixel transfer function becomes more linear for weak light-generated signals, whereas with conventional pixels, the pixel output signals are often distorted and even suppressed. The novel pixel circuit may find particular use in a portable digital image capture system such as a digital camera.
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