A method includes setting a circuit to a mode. A test tone having a first frequency is provided to the circuit for use in calibrating the circuit. A received signal is generated based on an output signal of the circuit, the received signal including a component having a second frequency that is a harmonic of the first frequency. A magnitude of the component having the second frequency in the received signal is measured. A delay of the circuit corresponding to the mode is adjusted according to the magnitude of the component.