Various embodiments are disclosed relating filter calibration with cell re-use. According to an example embodiment, an apparatus includes a first circuit, including a variable circuit element. The first circuit is adapted to output an output frequency signal during a calibration mode and to operate as a filter during a filter mode. A control circuit is coupled to the first circuit and is adapted to receive a reference frequency signal and to calibrate the first circuit by adjusting the variable circuit element based on the reference frequency signal and the output frequency signal during the calibration mode. The calibrated first circuit is configured to then operate as a filter during the filter mode.