| 摘要 |
<p>A method and apparatus for reducing noise in a light sensing circuit having a photodiode array (80) coupled to a charge amplifier (85) through a field effect transistor transfer switch (116). Thermal noise generated by the transfer switch (116) is combined with image signals inputted to the charge amplifier (85) resulting in an outputted noisy image signal. The invention eliminates this noise by taking two consecutive readings of the charge amplifier output, one before and one after closing the transfer switch (116) and after opening it. The thermal noise generated by the transfer switch (116), and added to the next reading of the charge amplifier output, is equal to the difference between these two readings. Once stored, this difference can be subtracted from the previously mentioned "next reading", resulting in the elimination of this noise term.</p> |
