Receiver of amplitude modulated signals
AssigneeMinnesota Mining and Manufacturing Company
InventorRobert J. Fretz
Life of this patent
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Abstract
An improvement to an implantable amplitude modulated frequency receiver wherein a resistor in the demodulator portion of a prior art receiver, which provides a discharge path for a capacitor, is replaced with an active circuit portion that includes a semiconductor device that provides the discharge path wherein the conductivity level of the semiconductor device is inversely related to the level of conduction of a rectifier to which the received amplitude modulated signal is applied. The active circuit portion improves the efficiency of the receiver in that less power is lost than in the case of the resistor the active circuit portion replaces.
Claims20
An improvement to an implantable amplitude modulated radio frequency receiver having an output adapted for connection to the body of a patient to apply the signal that is used as the modulating signal for an amplitude modulated radio frequency signal received by the receiver which includes a tuned circuit for receiving the amplitude modulated signal and a demodulator circuit portion connected to the tuned circuit for obtaining the modulating signal from the received amplitude modulated radio frequency signal for presentment to the output of the receiver, the demodulator circuit portion including a diode that has its output connected to a blocking capacitor and to a resistor that provides a discharge path for limited discharge of the blocking capacitor, the improvement including an active circuit portion that replaces the resistor, said active circuit portion having an active semiconductor device connected to the diode and blocking capacitor for providing a discharge path for limited discharge of the blocking capacitor, said active semiconductor device providing a level of conductivity which is inversely related to the level of conduction of the rectifier, said active circuit portion having a control circuit connected between the tuned circuit and said active semiconductor device for controlling the conductivity of said active semiconductor device whereby less power is used by said circuit portion than by the resistor replaced by said active circuit portion to provide a receiver of improved efficiency.
Dependencies are inferred from the claim text.