An integrated circuit, comprising: a communication and control unit including: a control unit configured to control an inverter, the inverter configured to convert an input voltage to an alternating current output signal for application to a transmission coil for reception by a receiver; and a communication unit configured to demodulate transmissions from the receiver; the control unit configured to cause the inverter to provide a first transmit power to the transmission coil, and the communication unit configured to receive a first power received signal from the receiver in response to the first transmit power, the control unit further configured to cause the inverter to provide a second transmit power to the transmission coil, and the communication unit configured to receive a second power received signal from the receiver in response to the second transmit power; and the communication and control unit configured to use the first transmit power, the first power received signal, the second transmit power and the second power received signal to determine a first gain and a first offset, wherein: when a third transmit power greater than the second transmit power is transmitted by the transmission coil, and a third power received signal is received by the communication unit from the receiver in response to the third transmit power, the communication and control unit determines a second gain and a second offset using the first transmit power, the first power received signal, the third transmit power and the third power received signal, wherein a foreign object detection is performed before determining the second gain and the second offset. a communication and control unit including: a control unit configured to control an inverter, the inverter configured to convert an input voltage to an alternating current output signal for application to a transmission coil for reception by a receiver; and a communication unit configured to demodulate transmissions from the receiver; the control unit configured to cause the inverter to provide a first transmit power to the transmission coil, and the communication unit configured to receive a first power received signal from the receiver in response to the first transmit power, the control unit further configured to cause the inverter to provide a second transmit power to the transmission coil, and the communication unit configured to receive a second power received signal from the receiver in response to the second transmit power; and the communication and control unit configured to use the first transmit power, the first power received signal, the second transmit power and the second power received signal to determine a first gain and a first offset, wherein: when a third transmit power greater than the second transmit power is transmitted by the transmission coil, and a third power received signal is received by the communication unit from the receiver in response to the third transmit power, the communication and control unit determines a second gain and a second offset using the first transmit power, the first power received signal, the third transmit power and the third power received signal, wherein a foreign object detection is performed before determining the second gain and the second offset.