An OLED display device, comprising: a display panel equipped with a plurality of pixels connected to data lines and sensing lines; a source drive IC configured to provide a data voltage to a pixel through a data line and equipped with a sensing block for obtaining sensing data related to driving characteristics of the pixel using a signal input through the sensing line, the sensing block including a sampling unit for sampling and holding a voltage of the sensing line and an analog-to-digital converter for converting the sampled voltage into a digital value; a first switch configured to control a connection via the sensing line between the pixel and the sensing block; a reference voltage source (Vref) configured to be connected to the sensing lines through a second switch during the display driving period; a test source (Vtest) configured to provide a test voltage or a test current to the sensing block through a third switch to obtain calibration data for the sensing block; and a controller configured to compensate input image data based on the calibration data and the sensing data and provide the compensated data to the source drive IC; wherein the first switch connects the pixel and the sensing block and the sensing block is configured to obtain the sensing data, in a vertical blank period or a power off sequence period except for the display driving period, wherein the source drive IC is configured to obtain calibration data, during a display driving period, in a state that the first switch disconnects the pixel and the sensing block, wherein the calibration data comprises the characteristics of the analog-to-digital converter in the sensing block. a display panel equipped with a plurality of pixels connected to data lines and sensing lines; a source drive IC configured to provide a data voltage to a pixel through a data line and equipped with a sensing block for obtaining sensing data related to driving characteristics of the pixel using a signal input through the sensing line, the sensing block including a sampling unit for sampling and holding a voltage of the sensing line and an analog-to-digital converter for converting the sampled voltage into a digital value; a first switch configured to control a connection via the sensing line between the pixel and the sensing block; a reference voltage source (Vref) configured to be connected to the sensing lines through a second switch during the display driving period; a test source (Vtest) configured to provide a test voltage or a test current to the sensing block through a third switch to obtain calibration data for the sensing block; and a controller configured to compensate input image data based on the calibration data and the sensing data and provide the compensated data to the source drive IC; wherein the first switch connects the pixel and the sensing block and the sensing block is configured to obtain the sensing data, in a vertical blank period or a power off sequence period except for the display driving period, wherein the source drive IC is configured to obtain calibration data, during a display driving period, in a state that the first switch disconnects the pixel and the sensing block, wherein the calibration data comprises the characteristics of the analog-to-digital converter in the sensing block.