Imaging apparatus and device
View Patent ↗An imaging apparatus capable of suppressing deterioration of image qualities and output properties is provided having one or more output circuits in series and a buffer circuit 6 , and processing luminance signals from photodetectors to output image information, the buffer circuit performing impedance conversion on signals outputted from a final output circuit of the one or more output circuits, the final output circuit being a source follower circuit that has an active element and a current source circuit 5 which is inserted between a source terminal of the active element and a reference voltage terminal, wherein the current source circuit and the buffer circuit 6 are external to a solid-state image sensor 1 having the photodetectors, and a main part of the current source circuit 5 and a main part of the buffer circuit 6 are in a single package.
1. An imaging apparatus having a solid-state image sensor in which a plurality of photodetectors are arranged, one or more output circuits in series and a buffer circuit, and processing luminance signals from the photodetectors to output image information, the buffer circuit performing impedance conversion on signals outputted from a final output circuit of the one or more output circuits, the final output circuit being a source follower circuit that has an active element and a current source which is inserted between a source terminal of the active element and a reference voltage terminal, wherein
the current source and the buffer circuit are external to a first semiconductor substrate on which the photodetectors are formed, and
a thickness of the first semiconductor substrate is less than 500 μm.
2. A imaging apparatus according to claim 1 , wherein
the thickness of the first semiconductor substrate is less than 400 μm.
3. An imaging apparatus according to claim 1 , wherein
a main part of the current source is constituted by a first active element, and
a main part of the buffer circuit is constituted by a second active element.
4. An imaging apparatus according to claim 3 , wherein
the first and second active elements are formed on a second semiconductor substrate that is different from the first semiconductor substrate, the second semiconductor substrate being included in the package.
5. An imaging apparatus according to claim 4 , wherein
the first semiconductor substrate and the second semiconductor substrate are connected to each other within the package.
6. An imaging apparatus according to claim 3 , wherein
the second active element is an element that improves a falling slew rate of the signals outputted from the final output circuit.
7. A imaging apparatus according to claim 6 , wherein
the second active element is constituted by a PNP transistor.
8. An imaging apparatus according to claim 3 , wherein
the second active element is constituted by a PNP transistor.
9. An imaging apparatus according to claim 3 , wherein
the current source includes an NPN transistor.
10. An imaging apparatus according to claim 3 , wherein
the current source includes a junction field-effect transistor.
11. A device used in an imaging apparatus having one or more output circuits in series and a buffer circuit, and processing luminance signals from the photodetectors to output image information, the buffer circuit performing impedance conversion on signals outputted from a final output circuit of the one or more output circuits, the final output circuit being a source follower circuit that has an active element and a current source which is inserted between a source terminal of the active element and a reference voltage terminal, wherein
the current source and the buffer circuit are external to a first semiconductor substrate on which the photodetectors are formed.
12. An imaging method used in an apparatus having a solid-state image sensor in which a plurality of photodetectors are arranged, one or more output circuits in series and a buffer circuit, and processing luminance signals from the photodetectors to output image information, the buffer circuit performing impedance conversion on signals outputted from a final output circuit of the one or more output circuits, the final output circuit being a source follower circuit that has an active element and a current source which is inserted between a source terminal of the active element and a reference voltage terminal, wherein
the current source and the buffer circuit are external to a first semiconductor substrate on which the photodetectors are formed, and
a thickness of the first semiconductor substrate is less than 500 μm.