Method and apparatus for detecting RF field strength
First Claim
Patent Images
1. A radio frequency (RF) circuit comprises:
- 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.
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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.
9 Citations
11 Claims
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1. 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 (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification