Patent ID: 7859296

Claim:
A calibration circuit, comprising: a gain control device configured to receive a gain control signal and to adjust a reference voltage to a predetermined level in response to the gain control signal; and a calibration device configured to update a calibration code by comparing a voltage generated according to a plurality of resistors with the reference voltage adjusted to the predetermined level by the gain control device, wherein each of the plurality of resistors is individually controlled to be turned on according to the calibration code, wherein the gain control device includes: a comparison amplifying unit configured to generate a control signal for adjusting a level of the output voltage according to a result of a comparison between the reference voltage and an output voltage; an output adjustment unit configured to adjust the level of the output voltage based on the control signal of the comparison amplifying unit; and a control unit configured to select one of the reference voltage and a ground voltage and transfer the selected voltage and select one of the output voltage and the ground voltage and transfer the selected one of the output voltage and the ground voltage to the comparison amplifying unit in response to a characteristic control signal.