FREE-BOOST CLASS-E AMPLIFIER

Systems, methods and apparatus for wireless charging are disclosed. A charging apparatus has an amplifier stage, a power switching stage and a controller. The amplifier stage has a choke that receives a current from an input of the amplifier stage, a resonant network coupled to an output of the choke and that provides an output current to a load, and a first switch configured to short the output of the choke to circuit ground when turned on. The power switching stage may be configured to couple a power supply to the input of the amplifier stage and may have a second switch operable to couple the input of the amplifier stage to circuit ground when turned on. The controller may be configured to control operation of the first switch and the second switch in accordance with a timing sequence that defines a cycle of the output current.