A circuit configured to sense a threshold voltage of an organic light emitting diode (OLED) of a display panel includes a sample and hold unit configured to receive the threshold voltage of the OLED, a first capacitor configured to sample the threshold voltage of the OLED, a second capacitor configured to charge-share the voltage on the first capacitor, an output terminal configured to output the voltage on the second capacitor, and an amplifier including an input terminal connected to the output terminal of the sample and hold unit. The sample and hold unit includes a first switching unit configured to selectively connect the OLED, the first capacitor, the second capacitor, the first capacitor and a first or second reference voltage, the second capacitor and the second or a third reference voltage, and the second capacitor and the output terminal.