Vision sensor including a voltage generation circuit for outputting a test bias voltage to a transistor and operating method thereof

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.