Method and apparatus for providing receiver dual channel coupling in a reader for RFID tags
First Claim
1. An improvement in a reader of RFID tags having an input stage comprising:
- a coil;
a first and second channel coupled in parallel to each other between said coil and said input stage of said reader, said first and second channels characterized by a response and recovery time to signals coupled thereto from said coil, said response and recovery time of said second channel being slower than said response and recovery time of said first channel, said first and second channels each having a node monitored by said input stage; and
a clamping device coupled between said first and second channels to clamp signal levels on said monitored node of first and second channels close to each other so that recovery time of said node is reduced.
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Abstract
The invention reduces recovery time in a receiving coil or antenna of an RFID reader by generating a reference voltage that then clamps the node on which the desired signal is monitored. The coil is coupled to parallel channels. One channel has a recovery time or capacitance very much less than the other parallel channel. The two channels have a monitored node which are clamped together or at least close together by means of a Schottky diode. The monitored nodes of both channels are coupled to the inputs of a differential amplifier. The output of the amplifier is the conditioned received signal from the coil used in the reader as the sensed signals from the RFID tags.
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Citations
20 Claims
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1. An improvement in a reader of RFID tags having an input stage comprising:
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a coil;
a first and second channel coupled in parallel to each other between said coil and said input stage of said reader, said first and second channels characterized by a response and recovery time to signals coupled thereto from said coil, said response and recovery time of said second channel being slower than said response and recovery time of said first channel, said first and second channels each having a node monitored by said input stage; and
a clamping device coupled between said first and second channels to clamp signal levels on said monitored node of first and second channels close to each other so that recovery time of said node is reduced. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of processing signals in a receiver of a reader of RFID tags, said reader having an input stage comprising:
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receiving signals from one of said RFID tags by use of a coil;
coupling said received signal from said coil to a first and second channel coupled in parallel to each other between said coil and said input stage of said reader, said first and second channels characterized by a response and recovery time to signals coupled thereto from said coil, said response and recovery time of said second channel being slower than said response and recovery time of said first channel, said first and second channels each having a node monitored by said input stage; and
clamping said monitored node of first and second channels close to each other so that recovery time of said node is reduced. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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Specification