Ad converting circuit, photoelectric converting apparatus, image pickup system, and driving method for ad converting circuit
AssigneeCanon Kabushiki Kaisha
InventorDaisuke Yoshida
Life of this patent
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Abstract
An apparatus for acquiring an i-bit digital code by a first stage AD conversion and a j-bit digital code by a second stage AD conversion includes a comparing unit which compares a reference signal and an analog signal in the first stage AD conversion; and an amplifying unit for outputting an amplified residual signal acquired by amplifying a difference between the analog signal and an analog signal corresponding to the i-bit digital code. The comparing unit compares the amplified residual signal and the reference signal in the second stage AD conversion.
Claims15
An apparatus for acquiring an i-bit digital code by a first stage AD conversion and a j-bit digital code by a second stage AD conversion comprising:
- a comparing unit which compares a reference signal and an analog signal in the first stage AD conversion;
- and
- an amplifying unit which outputs an amplified residual signal acquired by amplifying a difference between the analog signal and an analog signal corresponding to the i-bit digital code, wherein:
- i and j each is an integer equal to or greater than 2,
- the comparing unit compares the amplified residual signal and the reference signal in the second stage AD conversion,
- the amplifying unit comprises a differential amplifier, and
- the comparing unit and the amplifying unit share the differential amplifier.
An apparatus comprising:
- a differential amplifier;
- a counter which counts in a plurality of bits;
- and
- a memory, wherein
- the memory holds a count value of the counter at a time when a level of a first signal is changed, the first signal being output from the differential amplifier and indicating a result of a comparison of comparing between a reference signal and an analog signal performed by the differential amplifier;
- the differential amplifier outputs a residual signal acquired by amplifying a difference between the analog signal and the reference signal when the magnitude relationship between the reference signal and the analog signal is inverted;
- and
- the memory further holds the count value of the counter at a time when a level of a second signal is changed, the second signal being output from the differential amplifier and indicating a result of a comparison of comparing between the reference signal and the residual signal performed by the differential amplifier.
A driving method for an apparatus having a differential amplifier, the method comprising:
- generating an i-bit digital code (where i is an integer equal to or greater than 2) based on a level of a first signal, the first signal indicating a result of a comparison between an analog signal and a reference signal performed by the differential amplifier;
- amplifying the difference signal between a reference signal corresponding to the i-bit digital code and the analog signal by the differential amplifier;
- and
- generating a j-bit digital code (where j is an integer equal to or greater than 2) based on a level of a second signal, the second signal indicating a result of a comparison between the amplified difference signal and the reference signal performed by the differential amplifier.
Dependencies are inferred from the claim text.