Wireless charging device, a receiver device, and a method of operating the same

A wireless charging device comprising:

• a driver unit to generate an alternating current (AC) voltage signal for a time period;
• a transmitting unit including a capacitor and a coil to transmit the AC voltage signal;
• and
• a control unit configured to:
• detect a change in a voltage at a junction between the capacitor and the coil during the time period;
• determine that a receiver device or a foreign object is in proximity to the coil based on the change in the voltage being greater than a threshold value;
• and
• distinguish between the receiver device and the foreign object based on a duration of the change.

A method of a wireless charging device, the method comprising:

• generating, by a driver unit, an alternating current (AC) voltage signal for a first time period;
• transmitting, by a first coil and a first capacitor in a transmitting unit, the AC voltage signal;
• monitoring a change in a voltage at the first coil during the first time period;
• confirming a presence of a receiver device based on the change being greater than a threshold value for a predefined time period;
• and
• determining that a foreign object is present based on the change being greater than the threshold value for more than the predefined time period.