Vision sensor including a voltage generation circuit for outputting a test bias voltage to a transistor and operating method thereof
A vision sensor and an operating method of the vision sensor are provided. The vision sensor includes a pixel array including a plurality of pixels arranged in a form of a matrix; and a bias voltage generation circuit configured to provide a test bias voltage to the pixel array, wherein each of the plurality of pixels includes a sensing circuit configured to sense light and generate a first output voltage, wherein the first output voltage changes as the test bias voltage changes within a specific frame.
1. A vision sensor comprising:
a pixel array comprising a plurality of pixels comprising a first pixel; wherein the first pixel comprises a sensing circuit configured to generate a first output voltage based on an internal voltage generated based on changes in intensity of light, and generate a second output voltage based on a first test bias voltage received from a bias voltage generation circuit, and wherein the sensing circuit comprises:
a photoelectric conversion element configured to generate a photocurrent based on the changes in the intensity of the light;
a current-voltage conversion circuit comprising a first transistor connected to the photoelectric conversion element, the current-voltage conversion circuit configured to convert the photocurrent into the internal voltage; and
a source-follower configured to convert the internal voltage to the first output voltage,
wherein the first transistor is configured to receive the first test bias voltage, and
wherein the photocurrent flows through the first transistor.
2. The vision sensor of claim 1 , wherein the sensing circuit is configured to generate a third output voltage based on a second test bias voltage received from the bias voltage generation circuit, and
wherein a magnitude of the first test bias voltage is different from a magnitude of the second test bias voltage.
3. The vision sensor of claim 2 , wherein the sensing circuit is configured to control the first output voltage based on the second test bias voltage.
4. The vision sensor of claim 2 , wherein the vision sensor comprises the bias voltage generation circuit and the bias voltage generation circuit configured to generate a bias control signal for controlling a magnitude of a bias voltage comprising the first and second test bias voltages.
5. The vision sensor of claim 2 , wherein each of the plurality of pixels in the pixel array is configured to receive a same test bias voltage.
6. The vision sensor of claim 2 , wherein the vision sensor is configured to generate event data based on the first output voltage and selectively transmit the event data to a processor.
7. The vision sensor of claim 6 , wherein the vision sensor is configured to aperiodically transmit the event data to the processor.
8. The vision sensor of claim 6 , wherein the vision sensor is configured to periodically transmit the event data to the processor.
9. The vision sensor of claim 7 , wherein the vision sensor and the processor are implemented as separate chips.
10. The vision sensor of claim 7 , wherein the vision sensor and the processor are implemented as a single chip.
11. The vision sensor of claim 7 , wherein the first transistor is a p-type transistor.
12. A vision sensor comprising:
a pixel array comprising a plurality of pixels comprising a first pixel, the first pixel comprising a sensing circuit configured to sense changes in intensity of light and generate a first output voltage aperiodically based on an internal voltage generated based on the changes in the intensity of the light,
wherein the sensing circuit is configured to receive a test bias voltage from a voltage generation circuit and control the internal voltage based on the test bias voltage,
wherein the sensing circuit comprises a p-type transistor configured to receive a first test voltage and a n-type transistor configured to receive a second test voltage different from the first test voltage.
13. The vision sensor of claim 12 , wherein a level of the first output voltage stays constant even when the intensity of the light changes.
14. The vision sensor of claim 12 , wherein the vision sensor further comprise an interface configured to pack event signals generated based on the changes in the intensity of the light.
15. The vision sensor of claim 14 , wherein the interface comprises one of an address event representation interface, a mobile industry processor interface, and a parallel interface.
16. The vision sensor of claim 15 , wherein the interface is configured to periodically transmit the event signals to a processor.
17. The vision sensor of claim 15 , wherein the interface is configured to aperiodically transmit the event signals to a processor.