Patent ID: 6993297

Claim:
An impedance transformation circuit for use with a transmitter, a receiver, and an antenna, the transmitter providing a transmission signal for transmission by the antenna, the antenna providing a received signal having an associated signal parameter to the receiver, the impedance transformation circuit comprising: an impedance adjusting circuit between the antenna and receiver and transmitter, the impedance adjusting circuit being configured to selectively reduce the presented impedance difference between the transmitter and the antenna in response to a control signal and while the receiver is connected to the antenna, and to selectively reduce the presented impedance difference between the receiver and the antenna in response to the control signal and while the transmitter is connected to the antenna;and a controller that generates the control signal to change the presented impedance difference in response to the signal parameter, wherein the signal parameter is indicative of when the receiver is actively receiving signals and when the transmitter is actively transmitting signals, and the controller is configured to modify the control signal to reduce the presented impedance difference between the transmitter and the antenna when the transmitter is actively transmitting signals and the receiver is not actively receiving signals, and to modify the control signal to reduce the presented impedance difference between the antenna and the receiver when the transmitter is not actively transmitting signals and the receiver is actively receiving signals.