Patent ID: 7667547

Claim:
An oscillator comprising: a sensor circuit comprising an inductor and a capacitor, the sensor circuit being adapted to resonate at a resonant frequency; an electronic device physically disconnected from the sensor circuit, the electronic device comprising an input and an output, the input being connected to electrical ground through an electronic device coil, the electronic device being adapted to amplify an input signal to produce an output signal at the electronic device output, the electronic device comprising: an amplifier stage adapted to amplify the input signal, wherein the amplifier stage comprises circuitry adapted to provide a high amplifier stage input impedance to prevent the electronic device coil from changing the resonant frequency of the sensor circuit; and a feedback network connected to an input of the amplifier and an output of the amplifier stage and adapted to provide a feedback for the amplifier stage, the feedback network comprising a pulse generator configured to provide a start-up pulse and a high impedance for the feedback network at the input of the amplifier stage; and wherein the sensor circuit and the electronic device are electromagnetically coupled to obtain the input signal at the electronic device input, the output signal having characteristics associated with the resonant frequency of the sensor circuit, the characteristics comprising a frequency that is the same as the resonant frequency.