Method and Apparatus for Detecting RF Field Strength
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Accused Products
Abstract
A method and apparatus for detecting RF field strength. A field strength reference generator develops a field strength reference current as a function of a field strength of a received RF signal; and a field strength quantizer develops a digital field-strength value indicative of the field strength reference current. In one embodiment, detected field strength is used to dynamically vary the impedance of a tank circuit whereby, over time, induced current is maximized. In another embodiment, using the quantized field strength to sense changes to the environment to which the RFID tag is exposed.
10 Citations
17 Claims
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1-6. -6. (canceled)
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7. A radio frequency (RF) circuit comprises:
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an antenna operably coupled to receive an RF signal; a tank circuit coupled to the antenna and having a selectively variable impedance; a tuning circuit adapted to dynamically vary the impedance of the tank circuit, and to develop a first quantized value representative of a change to impedance of the tank circuit; and a detector circuit adapted to develop a second quantized value representative of a field strength of the received RF signal. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification