Wireless Power Charging

A current sensing circuit and a minimum operating frequency for a wireless power transmission system is presented. A method of measuring current through a wireless power transmit coil, includes receiving a signal from a switching circuit into a sampling circuit; filtering the sampled signal from the sampling circuit; biasing the filtered sampled signal, wherein the biasing occurs only when the sampling circuit is active; and amplifying the biased signal to provide a transmit coil current signal. A method of measuring current through a wireless power transmit coil, includes receiving a signal from a switching circuit into a sampling circuit; filtering the sampled signal from the sampling circuit; biasing the filtered sampled signal, wherein the biasing occurs only when the sampling circuit is active; and amplifying the biased signal to provide a transmit coil current signal.