Circuit for detecting a transponder

摘要

A circuit for remotely detecting a transponder includes a tank circuit (40) having a predetermined quality factor. The tank includes a transformer having a tap (48). A quality factor lowering means (42) is connected to the tank circuit (40) for broadening the bandwidth of the tank circuit (40) to include the transmit and receive frequencies. A control module (50) generates transmit signals and receives receive signals. A wire pair means (52) connected between said control module (50) and the coil circuit (40) provides an inductance cancelling and substantially noise immune connection between the coil circuit and the control module. One (54) of the wires is connected to the tap (48). The other of the wires (52) is connected to ground at the control module (50) for providing a ground to said transformer. <IMAGE>