CCD signal read-out circuit free from ailiasing of high-frequency noises
First Claim
1. A charge coupled device (CCD) signal read-out circuit for receiving a first signal output from a CCD and for substantially removing a reset noise from the first signal by correlated double sampling to produce a second signal that is substantially free from the reset noise, the first signal including a plurality of pixel periods each pixel period comprising a reset period, a feed-through period, and a pixel signal period, said CCD signal read-out circuit comprising:
- first and second signal extractor circuits for receiving the first signal and extracting a feed-through signal and a pixel signal from each respective pixel period;
first and second low-pass filter circuits for low-pass filtering the feed-through signal and the pixel signal extracted by said first and second signal extractor circuits, respectively;
a signal hold circuit for sampling and holding the feed-through signal filtered by said first low-pass filter circuit; and
a differential amplifier for subtracting the pixel signal filtered by said second low-pass filter circuit from a signal sampled and held by said signal hold circuit and outputting a resultant signal as the second signal.
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Accused Products
Abstract
A CCD signal read-out circuit is operative, upon receipt of a CCD signal outputted from a CCD, to output an output signal from which a reset noise has been removed through correlated double sampling. The CCD signal includes pixel periods each comprising a reset period, a succeeding feed-through period and a further succeeding pixel signal period. The read-out circuit comprises: first and second signal extractors for receiving the CCD signal and extracting a feed-through signal and a pixel signal for the respective pixel periods, respectively; first and second low-pass filters for low-pass filtering the feed-through signal and the pixel signal extracted by the first and second signal extractors, respectively; a signal hold circuit for sampling and holding the feed-through signal filtered by the first low-pass filter; and a differential amplifier for subtracting the pixel signal filtered by the second low-pass filter from a signal sampled and held by a signal hold circuit and outputting the resultant output signal.
41 Citations
21 Claims
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1. A charge coupled device (CCD) signal read-out circuit for receiving a first signal output from a CCD and for substantially removing a reset noise from the first signal by correlated double sampling to produce a second signal that is substantially free from the reset noise, the first signal including a plurality of pixel periods each pixel period comprising a reset period, a feed-through period, and a pixel signal period, said CCD signal read-out circuit comprising:
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first and second signal extractor circuits for receiving the first signal and extracting a feed-through signal and a pixel signal from each respective pixel period; first and second low-pass filter circuits for low-pass filtering the feed-through signal and the pixel signal extracted by said first and second signal extractor circuits, respectively; a signal hold circuit for sampling and holding the feed-through signal filtered by said first low-pass filter circuit; and a differential amplifier for subtracting the pixel signal filtered by said second low-pass filter circuit from a signal sampled and held by said signal hold circuit and outputting a resultant signal as the second signal. - View Dependent Claims (2)
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3. A charge-coupled device (CCD) signal read-out circuit for receiving a first signal outputted from a CCD, and substantially removing a reset noise from the first signal by correlated double sampling to produce a second signal that is substantially free from reset noise, the first signal including a plurality of pixel period each pixel period comprising a reset period, a feed-through period, and a pixel signal period, said CCD signal read-out circuit comprising:
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first and second signal extractor circuits for receiving the first signal and extracting a feed-through signal and an associated pixel signal from each respective pixel period; first and second low-pass filter circuits for low-pass filtering the feed-through signal and the pixel signal extracted by said first and second signal extractor circuits, respectively; a delay circuit for delaying the feed-through signal filtered by said first low-pass filter circuit until the associated pixel signal period comes; and a differential amplifier for subtracting the pixel signal filtered by said second low-pass filter circuit from a signal delayed by said delay circuit and outputting a resultant signal as the second signal. - View Dependent Claims (4)
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5. A charge-coupled device (CCD) signal read-out circuit for receiving a first signal outputted from a CCD, and substantially removing a reset noise from the first signal by correlated double sampling to produce a second signal that is substantially free from the reset noise, the first signal including a plurality of pixel periods, each comprising a reset period, a feed-through period, and a pixel signal period, said CCD signal read-out circuit comprising:
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a delay circuit for delaying the first signal until a pixel signal period comes and producing a delayed signal; a first signal extractor circuit for receiving the delayed signal and extracting a feed-through signal from each pixel period; a second signal extractor circuit for receiving the first signal and extracting the pixel signal from each pixel period; first and second low-pass filter circuits for low-pass filtering the feed-through signal and the pixel signal extracted by said first and second signal extractor circuits, respectively; and a differential amplifier for subtracting the pixel signal filtered by said second low-pass filter circuit from the feed-through signal filtered by said first low-pass filter circuit and outputting a resultant signal as the second signal. - View Dependent Claims (6)
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7. A charge-coupled device (CCD) signal read-out circuit for receiving a first signal outputted from a CCD, and substantially removing a reset noise from the first signal by correlated double sampling to produce a second signal that is substantially free from the reset noise, the first signal including a plurality of pixel periods, each pixel period comprising a reset period, a feed-through period, and a pixel signal period, said CCD signal read-out circuit comprising:
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first and second signal extractor circuits for receiving the first signal and extracting a feed-through signal and a pixel signal from each respective pixel period; first and second averaging means for averaging the feed-through signal and the pixel signal extracted by said first and second signal extractor circuits and for phase shifting at least one of;
said averaged feed-through signal and said averaged pixel signal to bring both of the signals in phase; anda differential amplifier for producing a difference between signals outputted from said first and second averaging means and outputting a resultant signal as the second signal. - View Dependent Claims (8, 9, 10)
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11. A charge-coupled device (CCD) signal read-out circuit for receiving a first signal outputted from a CCD including a plurality of pixel periods, each pixel period comprising a feed-through period and a signal period, and for substantially reducing a correlated noise and a high-frequency noise included in the signal period to produce a second signal that is substantially free from the correlated noise and the high-frequency noise, said CCD signal read-out circuit comprising:
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first and second signal extractor circuits for receiving the first signal and for extracting levels of the feed-through period and the signal period for each respective pixel period to develop a feed-through signal and a pixel signal; a signal inverter circuit for inverting one of the feed-through signal and the pixel signal extracted by said first and second signal extractor circuits, respectively, and for outputting a resultant signal in the form of a serial signal; and an averaging circuit for averaging the serial signal output from said signal inverter circuit to produce a signal in which the correlated noise and the high-frequency noise have substantially been reduced. - View Dependent Claims (12, 13, 14, 15)
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16. A charge-coupled device (CCD) signal read-out circuit for receiving a first signal outputted from a including a plurality of pixel periods, each pixel period comprising a feed-through period and a signal period, and for substantially reducing a correlated noise and a high-frequency noise included in the signal period to produce a second signal that is substantially free from the correlated noise and the high-frequency noise, said CCD signal read-out circuit comprising:
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first and second signal extractor circuits for receiving the first signal and for extracting levels of the feed-through period and the signal period for each respective pixel period to develop a feed-through signal and a pixel signal; a signal inverter circuit for inverting one of the feed-through signal and the pixel signal extracted by said first and second signal extractor circuits, respectively, and for outputting a resultant signal in the form of a serial signal; a selector circuit for selecting from said serial signal a part of said serial signal for a first pixel period for developing a first serial signal, and selecting from said serial signal a part of said serial signal for a second pixel period for developing a second serial signal; a first averaging circuit for averaging the first serial signal to output a signal wherein the correlated noise and the high-frequency noise have substantially been reduced; and a second averaging circuit for averaging the second serial signal to output a signal wherein the correlated noise and the high-frequency noise have substantially been reduced. - View Dependent Claims (17, 18)
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19. A charge-coupled device (CCD) signal read-out circuit for receiving a first signal outputted from a CCD including a plurality of pixel periods, each pixel period comprising a feed-through period and a signal period, and for substantially reducing a correlated noise and a high-frequency noise included in the signal period to produce a second signal that is substantially free from the correlated noise and the high-frequency noise, said CCD signal read-out circuit comprising:
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a first signal extractor circuit for receiving the first signal and extracting levels of the feed-through period and the signal period during a first pixel period to develop a first feed-through signal and a first pixel signal; a second signal extractor circuit for receiving the first signal and extracting levels of the feed-through period and the signal period during a second pixel period to develop a second feed-through signal and a second pixel signal; a first signal inverter circuit for inverting one of the first feed-through signal and the first pixel signal and outputting a resultant signal as a first serial signal; a second signal inverter circuit for inverting one of the second feed-through signal and the second pixel signal and outputting a resultant signal as a second serial signal; a first averaging circuit for averaging the first serial signal output from said first signal inverter circuit to output a signal wherein the correlated noise and the high-frequency noise have substantially been reduced. - View Dependent Claims (20, 21)
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Specification