Solid-state image sensor, imaging device, and ad converter

An imaging device comprising:

• a lens module causing incident light to pass therethrough;
• and
• a solid-state image sensor which converts voltages of a plurality of pixels storing charges corresponding to an amount of the incident light by photoelectric conversion to output a digital image,
• wherein the solid-state image sensor includes
• a first buffer circuit connected to a first pixel and a second pixel of the plurality of pixels, and
• a first analog-to-digital conversion circuit converting a voltage signal from the first buffer circuit into a digital signal,
• wherein the first buffer circuit includes
• a first voltage holding circuit connected to the first pixel,
• a second voltage holding circuit connected to the second pixel, and
• a first switch circuit selectively switching a voltage holding circuit which outputs a voltage signal to the first analog-to-digital conversion circuit between the first voltage holding circuit and the second voltage holding circuit, and
• wherein the first buffer circuit carries out an operation of holding a voltage signal of the first pixel in the first voltage holding circuit and an operation of holding a voltage signal of the second pixel in the second voltage holding circuit in parallel with each other.

An analog-to-digital converter converting a voltage signal to output a digital signal, the analog-to-digital converter comprising:

• a buffer circuit to which a first voltage signal and a second voltage signal are input;
• and
• an analog-to-digital conversion circuit converting a voltage signal from the buffer circuit into a digital signal,
• wherein the buffer circuit includes
• a first terminal to which the first voltage signal is input,
• a second terminal to which the second voltage signal is input,
• a first voltage holding circuit connected to the first terminal,
• a second voltage holding circuit connected to the second terminal, and
• a first switch circuit selectively switching a voltage holding circuit which outputs a voltage signal to the analog-to-digital conversion circuit between the first voltage holding circuit and the second voltage holding circuit, and
• wherein the buffer circuit carries out an operation of holding the first voltage signal in the first voltage holding circuit and an operation of holding the second voltage signal in the second voltage holding circuit in parallel with each other.