Electronic device including fingerprint sensor and operating method thereof

An electronic device comprising:

• a window having a first refractive index with respect to light;
• a light emitting module disposed on one surface of the window and configured to radiate infrared light such that the infrared light is totally reflected inside the window in correspondence with the first refractive index;
• a connection member having a second refractive index and is interposed between the window and the light emitting module;
• and
• a fingerprint sensor disposed under the window and configured to obtain a fingerprint of a user based on a user input on the window using scattered light of the infrared light.

A method of operating an electronic device, the method comprising:

• receiving a user input;
• activating a light emitting module disposed in an area under a periphery of a window such that infrared light is emitted while being totally reflected toward an inside of the window;
• generating a fingerprint image by collecting the infrared light reflected on a surface of a finger disposed on the window while the infrared light is totally reflected inside the window;
• and
• performing fingerprint authentication associated with the fingerprint image.