Importance

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Abstract

A power supply self-contained within a portable RF/ID transponder includes a full wave rectifier having an input for receiving an antenna signal and outputs for providing power supply and ground voltages, wherein the power supply voltage has a time varying voltage waveform corresponding to the electric field generated by a reader/controller. The power supply further includes a clamping circuit for regulating the power supply voltage and a ferroelectric filter/storage capacitor coupled between the power supply and ground outputs of the full wave rectifier. The power supply further includes a power enable circuit for constantly monitoring the supply voltage waveform and for providing a power enable indication after an initial portion of the supply voltage waveform rises above a predetermined power-up threshold level and for removing the power enable indication when a terminal portion of the supply voltage waveform falls below a predetermined power-down level. The power-up and power-down thresholds describe a proper voltage range of operation for the ferroelectric memory in the transponder. The power enable indication is provided to the ferroelectric memory so that the memory is only operated when the power supply voltage is within the proper range so that data is valid during read and write operations.

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First Claim