Systems, methods and apparatus for wireless charging are disclosed. One method includes providing a first charging current to a first transmitting coil in a wireless charging device, where the first transmitting coil is coupled to a receiving coil in a first power receiving device, providing a second charging current to a second transmitting coil in the wireless charging device, where the second transmitting coil is coupled to a receiving coil in a second power receiving device, the first charging current and the second charging current being provided at different frequencies from one another, receiving a first modulated signal from the first power receiving device, where the first modulated signal includes a carrier signal provided at a frequency corresponding to the frequency of the first charging current, and filtering the first modulated signal using a band-pass filter configured to block a second modulated signal transmitted by the second power receiving device.