A circuit arrangement for calibrating a circuit in an integrated circuit device is described. The circuit arrangement may comprise a main circuit configured to receive input data at a first input and generate output data at a first output, wherein the output data is based upon the input data and a function of the main circuit; a replica circuit configured to receive calibration data at a second input and generate calibration output data, based upon the calibration data, at a second output, wherein the replica circuit provides a replica function of the function of the main circuit; and a calibration circuit configured to receive the output data from the main circuit during a foreground calibration mode, and the calibration output data from the replica circuit during a background calibration mode; wherein the calibration circuit provides control signals to the main circuit during the background calibration mode. A method of calibrating a circuit in an integrated circuit device is also described.