CMOS image sensor
A low-power CMOS image sensor that gets distinct images in which interference does not occur between adjacent pixels without changing an element in a circuit. Each of pixel circuits arranged like a matrix converts incident light into electrical signals with a photoelectric conversion element. Image signals output from pixel circuits adjacent to each other in a horizontal direction are input to a signal processing circuit in each column, undergo predetermined signal processing, and are switched and output in order by a horizontal scanning circuit. The signal processing circuits are arranged and each of fixed potential wirings parallel to one another is located between adjacent signal processing circuits. Therefore, adjacent signal processing circuits are electrically shielded by a fixed potential wiring.
1. A CMOS image sensor for getting images by outputting in order image signals sensed in each of pixel areas arranged like a matrix on the basis of X-Y addressing, the sensor comprising:
a plurality of pixel circuits arranged like a matrix and each including a photoelectric conversion element to make the photoelectric conversion of incident light for outputting the image signals corresponding to one pixel;
a plurality of signal processing circuits arranged by the number equal to that of the pixel circuits arranged in a horizontal direction and connected to all the pixel circuits arranged in a vertical direction for performing predetermined signal processing on the image signals from each of all the pixel circuits arranged in the vertical direction;
a horizontal scanning circuit for switching and outputting in order the image signals from the plurality of signal processing circuits; and
fixed potential wirings parallel to one another and each located between two of the plurality of signal processing circuits arranged.
2. The CMOS image sensor according to claim 1 , wherein the fixed potential wirings are always formed in the same wiring layer where signal transmission wirings in the plurality of signal processing circuits for transmitting the image signals are formed.
3. The CMOS image sensor according to claim 1 , wherein if the signal transmission wirings in each of the plurality of signal processing circuits are arranged parallel to one another in the same wiring layer, the fixed potential wirings are also located between any two of the signal transmission wirings.
4. The CMOS image sensor according to claim 1 , wherein the fixed potential wirings are set to GND potential.
5. The CMOS image sensor according to claim 1 , wherein if a wiring for shading light having an opening only over an area where the plurality of pixel circuits are arranged for preventing the incident light from striking a portion other than the area is further located, the fixed potential wirings are connected to the wiring for shading light.
6. The CMOS image sensor according to claim 5 , wherein the wiring for shading light is set to GND potential.
7. The CMOS image sensor according to claim 1 , wherein if common power supply voltage shared by each of the plurality of pixel circuits and the horizontal scanning circuit is supplied, the fixed potential wirings are set to the common power supply voltage.
8. The CMOS image sensor according to claim 1 , wherein the fixed potential wirings are supplied with voltage via an independent voltage supply wiring separated at a wiring pad portion located in a semiconductor chip formed.
9. The CMOS image sensor according to claim 1 , wherein the fixed potential wirings are supplied with voltage from an independent voltage source located outside a semiconductor chip formed.
10. The CMOS image sensor according to claim 1 , wherein each of the plurality of signal processing circuits includes a correlated double sampling circuit.
11. The CMOS image sensor according to claim 10 , wherein if each of the correlated double sampling circuits includes a capacitive element for sampling the image signals from each of the plurality of pixel circuits connected to the correlated double sampling circuits, the fixed potential wirings are located parallel to the signal transmission wirings connected to both ends of the capacitive element.
12. The CMOS image sensor according to claim 10 , wherein if the correlated double sampling circuits are supplied with dedicated reference voltage, the fixed potential wirings are set to the reference voltage.