A power transmitter includes: a first switch coupled between a first node and a reference voltage node; a second switch configured to be coupled between a power supply and the first node; a coil and a capacitor coupled in series between the first node and the reference voltage node; a first sample-and-hold (S&H) circuit having an input coupled to the first node; and a timing control circuit configured to generate a first control signal, a second control signal, and a third control signal that have a same frequency, where the first control signal is configured to turn ON and OFF the first switch alternately, the second control signal is configured to turn ON and OFF the second switch alternately, and where the third control signal determines a sampling time of the first S&H circuit and has a first pre-determined delay from a first edge of the first control signal.