According to one aspect of the present invention, there is provided a method of calibrating an oscillator within a radio-frequency identification (RFID) circuit for use in an RFID tag. A plurality of calibration values is stored within a memory structure associated with the RFID circuit. Each of the calibration values corresponds to a respective oscillation frequency of the oscillator. A selected calibration value is selected from the plurality of calibration values stored within the memory structure, according to a first selection criterion. The oscillator is then calibrated in accordance with the selected calibration value.