Antenna impedance modulation method
First Claim
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1. A circuit for modulating the impedance of an antenna while maintaining a supply of voltage from signals received on the antenna, the circuit comprising:
- a charge pump coupled to the antenna, the charge pump comprising a plurality of charge pump stages adapted to supply power extracted from the received signals on the antenna, each charge pump stage having an input coupled to the antenna and an output coupled to a succeeding charge pump stage, with the output of the last charge pump stage coupled to a voltage supply output; and
a switch element coupled between the antenna and the output of one of the charge pump stages that is not the last charge pump stage to couple and uncouple the output of the one of the charge pump stages that is not the last stage to the antenna in response to a control signal while the succeeding charge pump stage or stages continue supplying voltage on the voltage supply output.
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Abstract
A method for modulating the impedance of an antenna circuit supplying pump signals to a charge pump comprising at least one first pump stage and one last pump stage, the last pump stage supplying a continuous voltage. The output of the first pump stage is short-circuited by means of a switch and the last pump stage goes on pumping electric charges and supplying the continuous voltage. Application in particular to RFID passive transponders.
5 Citations
17 Claims
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1. A circuit for modulating the impedance of an antenna while maintaining a supply of voltage from signals received on the antenna, the circuit comprising:
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a charge pump coupled to the antenna, the charge pump comprising a plurality of charge pump stages adapted to supply power extracted from the received signals on the antenna, each charge pump stage having an input coupled to the antenna and an output coupled to a succeeding charge pump stage, with the output of the last charge pump stage coupled to a voltage supply output; and a switch element coupled between the antenna and the output of one of the charge pump stages that is not the last charge pump stage to couple and uncouple the output of the one of the charge pump stages that is not the last stage to the antenna in response to a control signal while the succeeding charge pump stage or stages continue supplying voltage on the voltage supply output. - View Dependent Claims (2, 3)
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4. A method, comprising:
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generating a control signal; and applying the control signal to a switch to periodically couple and uncouple at least one charge pump stage that is not a last charge pump stage of the charge pump to an antenna while allowing succeeding charge pump stages to continue supplying voltage to the voltage supply output to modulate the impedance of an antenna while maintaining a supply of power from signals received on the antenna. - View Dependent Claims (5, 6)
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7. A device, comprising:
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a charge pump circuit coupled to an antenna, the charge pump circuit having series-connected charge pump stages adapted to extract power from signals received from the antenna and to output a supply voltage to a voltage supply output terminal; and a switch coupled to the charge pump circuit and the antenna and adapted to connect a portion of the charge pump circuit to the antenna to modulate an impedance of the antenna while a remaining portion of the charge pump circuit continues to supply voltage to the voltage supply output terminal, the switch coupled to an output of one of the series connected charge pump stages that is not a last stage, the switch having a control terminal adapted to receive a control signal that is generated by a control circuit utilizing binary data stored in the device. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14)
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15. A system, comprising:
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a memory; a charge pump coupled to an antenna that is structured to receive signals, the charge pump including a plurality of charge pump stages structured to supply power extracted from the received signals on the antenna, each charge pump stage having an input coupled to the antenna and an output coupled to a succeeding charge pump stage, with the output of the last charge pump stage coupled to a voltage supply output; a switch element coupled between the antenna and the output of one of the charge pump stages that is not the last charge pump stage to couple and uncouple the output of the one of the charge pump stages that is not the last stage to the antenna in response to a control signal while the succeeding charge pump stage or stages continue supplying voltage on the voltage supply output; a control circuit coupled to the memory and to the switch element and structured to generate the control signal as a binary signal to open and close the switch element in response to data stored in the memory. - View Dependent Claims (16, 17)
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Specification