Imaging device and electronic device
An imaging device that has an image processing function and is capable of operating at high speed is provided. The imaging device has an additional function such as image processing, image data obtained by an imaging operation is binarized in a pixel unit, and a product-sum operation is performed using the binarized data. A memory circuit is provided in the pixel unit and retains a weight coefficient used for the product-sum operation. Thus, an arithmetic operation can be performed without the weight coefficient read from the outside every time, whereby power consumption can be reduced. Furthermore, a pixel circuit, a memory circuit, and the like and a product-sum operation circuit and the like are stacked, so that the lengths of wirings between the circuits can be reduced, and high-speed operation with low power consumption can be performed.
1 . An imaging device comprising:
a first layer comprising a pixel circuit; and
a second layer comprising a product-sum operation circuit and a binarization circuit,
wherein the first layer comprises a region overlapping with the second layer,
wherein the pixel circuit comprises a first transistor and a second transistor,
wherein the first layer further comprises:
a first metal oxide layer comprising a channel formation region of the first transistor;
a second metal oxide layer comprising a channel formation region of the second transistor;
a first gate wiring comprising a region which functions as a gate electrode of the first transistor; and
a second gate wiring comprising a region which functions as a gate electrode of the second transistor,
wherein, in a top view, each of the first metal oxide layer and the second metal oxide layer extend in a first direction, and
wherein, in the top view, each of the first gate wiring and the second gate wiring extend in a second direction.
2 . The imaging device according to claim 1 ,
wherein the first layer further comprises a memory circuit, and
wherein the memory circuit comprises a transistor which comprises a metal oxide in a channel formation region.
3 . The imaging device according to claim 1 , further comprising a third layer,
wherein the third layer comprises a memory circuit, and
wherein the memory circuit comprises a transistor which comprises a metal oxide in a channel formation region.
4 . The imaging device according to claim 1 ,
wherein each of the product-sum operation circuit and the binarization circuit comprises a transistor which comprises silicon in a channel formation region.
5 . The imaging device according to claim 1 ,
wherein the pixel circuit is electrically connected to the binarization circuit.
6 . The imaging device according to claim 1 ,
wherein the product-sum operation circuit is electrically connected to the binarization circuit.