Patent ID: 7915846

Claim:
An apparatus comprising: a secondary coil configured to carry a current induced by a changing magnetic field; a delay switch coupled to the secondary coil; and an output node coupled to the delay switch, wherein the delay switch comprises: a transistor including a first end and a second end of a channel and a control node configured to control a resistance across the channel, the first end being coupled to a first end of the secondary coil and to a first end of a first capacitor, the control node being coupled to a second end of the first capacitor, and a second end of the channel being coupled to the output node of the apparatus; the first capacitor, the first capacitor including the first end coupled to the first end of the secondary coil and to the first end of the channel, the first capacitor further including the second end coupled to the control node; and a first resistor, the first resistor including a first end coupled to the second end of the first capacitor and to the control node of the transistor, the first resistor further including a second end coupled to ground.