Image pickup device and electronic apparatus
The present technology relates to an image pickup device and an electronic apparatus capable of preventing degradation of the picture quality. A plurality of current sources can be selectively connected to an output terminal for outputting a reference signal having a level that varies, and a plurality of terminating resistors are connected to the output terminal. The terminating resistors that are to supply current of current sources that are connected to the output terminal are connected by a plurality of switches, and current of current sources that are not connected to the output terminal is supplied to the switches. The present technology can be applied, for example, to image pickup devices that perform AD conversion using a reference signal and so forth.
1. An image pickup device, comprising:
a pixel having a photoelectric conversion device that performs photoelectric conversion and configured to output an electric signal;
a reference signal generation unit configured to generate a reference signal having a level that varies;
a comparison unit configured to compare the electric signal and the reference signal with each other; and
a counting unit configured to perform AD (Analog to Digital) conversion of the electric signal by performing counting of a count value in response to a result of the comparison between the electric signal and the reference signal, wherein
the reference signal generation unit includes:
a plurality of current sources whose connection to an output terminal for outputting the reference signal is selectable,
a plurality of terminating resistors connected to the output terminal, and
a plurality of switches configured to select the plurality of terminating resistors that are to supply first current of a plurality of first current sources of the plurality of current sources that are connected to the output terminal, and
the reference signal generation unit is further configured so as to supply second current of a plurality of second current sources of the plurality of current sources that are not connected to the output terminal to the plurality of switches.
2. The image pickup device according to claim 1 , wherein
the plurality of switches are connected in series to the plurality of terminating resistors, and
when a switch of the plurality of switches is switched on, third current of a current source of the plurality of first current sources connected to the output terminal flows through a terminating resistor of the plurality of terminating resistors connected to the switch.
3. The image pickup device according to claim 2 , wherein
the second current of the plurality of second current sources that are not connected to the output terminal is supplied to the plurality of switches connected to the plurality of terminating resistors to which the first current of the plurality of first current sources connected to the output terminal flows.
4. The image pickup device according to claim 2 , further comprising:
a different switch configured to switch on/off connection of the plurality of second current sources that are not connected to the output terminal to a connection point between the plurality of terminating resistors and the plurality of switches; and
the different switch being switched on/off in synchronism with the plurality of switches.
5. The image pickup device according to claim 1 , wherein, as a number of the plurality of first current sources connected to the output terminal increases or decreases, the level outputted from the output terminal varies.
6. An electronic apparatus, comprising:
an optical system configured to collect light; and
an image pickup device configured to receive the light to pick up an image, wherein
the image pickup device includes:
a pixel having a photoelectric conversion device that performs photoelectric conversion and configured to output an electric signal,
a reference signal generation unit configured to generate a reference signal having a level that varies,
a comparison unit configured to compare the electric signal and the reference signal with each other, and
a counting unit configured to perform AD (Analog to Digital) conversion of the electric signal by performing counting of a count value in response to a result of the comparison between the electric signal and the reference signal, wherein
the reference signal generation unit includes
a plurality of current sources whose connection to an output terminal for outputting the reference signal is selectable,
a plurality of terminating resistors connected to the output terminal, and
a plurality of switches configured to select the plurality of terminating resistors that are to supply first current of a plurality of first current sources of the plurality of current sources that are connected to the output terminal, and
the reference signal generation unit is further configured so as to supply second current of a plurality of second current sources of the plurality of current sources that are not connected to the output terminal to the plurality of switches.