A circuit for generating a modulated signal is disclosed. The circuit includes a constant current source. The circuit further includes a first switch that is coupled to the constant current source. The circuit also includes a second switch that is coupled to the first switch and a ground. The first switch and the second switch are coupled to a third switch. The third switch is coupled to a first integrated circuit pad. The first integrated circuit pad is defined to be used for coupling the third switch to a resonance circuit.