A proximity detection circuit. An oscillator circuit is adapted to provide
charge to an antenna. An operational amplifier, operated as a unity gain
follower, receives an antenna signal which is representative of an
external capacitive load on the antenna. A detector circuit receives the
antenna signal via the operational amplifier and outputs a detection
signal in response to changes in the antenna signal. A comparator
receives the detection signal and is adapted to generate an output signal
in response thereto.