POWER ADJUSTMENT IN A NON-REGULATED WIRELESS CHARGING SYSTEM

A system (17) of a power device (1) and a portable device (18) for wireless charging of a battery (3) of the portable device (18), which power device (1) comprises an antenna (4) to emit a magnetic field with a carrier frequency to power the portable device (18) which comprises an antenna (5) exposed to the magnetic field and connected via a matching stage (15) to a rectifier stage (6), to rectify an antenna signal, and which portable device (18) comprises a charge stage (20), to sense and limit the rectified antenna signal, to provide an input voltage (UI) at an input pin (10) of a charger IC (8) of the portable device (18) that provides a first charge current (IC) at an output pin connected to the battery (3) to charge the battery (3) for a first period of time (T1) as power source with the constant first charge current (IC), wherein the portable device (18) comprises a detuning stage (19) to change the resonance frequency of the antenna (5) of the portable device (18) and that the charge stage (20) is built to limit the input voltage (UI) for the charger IC (8) by steering the detuning stage (19) to detune the resonance frequency of the antenna (5) of the portable device (18) away from the carrier frequency of the magnetic field.