Dynamic transmitter signal envelope shaping control for NFC or RFID devices
First Claim
1. A method for dynamically controlling transmitter (TX) signal envelope shape, the method comprising:
- sensing a TX current and/or voltage of a transmitter;
sensing a matching current and/or voltage of an antenna and matching network;
determining a Q (quality) factor based on the TX current and/or voltage and the matching current and/or voltage;
dynamically controlling the transmitter (TX) signal envelope shape based on the Q factor.
1 Assignment
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Accused Products
Abstract
Transmitter (TX) modulation envelope parameters are defined in RF standards (e.g., ISO 14443, NFC Forum, EMVCo). These envelope parameters include rise/fall times, modulation index, etc. For standards compliancy, these envelope parameters must be within the respective limits. For example, shaping parameters are influenced by detuning the antenna with a counterpart device like a card or mobile phone, or by thermal influences on the matching network. This disclosure describes an NFC or RFID device that is able to detect and measure the detuning on the antenna and/or the matching network change. With this information, the NFC or RFID device can dynamically control the shaping parameters of the envelope, instead of relying on one single static configuration setting for the transmitter. In particular, changes in the Q (quality) factor are used for dynamically controlling the transmitter signal envelope shape for compensating the effect of antenna detuning and/or matching network variation.
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Citations
20 Claims
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1. A method for dynamically controlling transmitter (TX) signal envelope shape, the method comprising:
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sensing a TX current and/or voltage of a transmitter; sensing a matching current and/or voltage of an antenna and matching network; determining a Q (quality) factor based on the TX current and/or voltage and the matching current and/or voltage; dynamically controlling the transmitter (TX) signal envelope shape based on the Q factor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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13. A device for dynamically controlling transmitter (TX) signal envelope shape, the device comprising:
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an antenna and matching circuit configured to be driven by a TX current corresponding to a TX voltage; a first sensor configured to sense the TX current and/or voltage; a second sensor configured to sense a matching current and/or voltage of the antenna and matching network; a control unit configured to; determining a Q (quality) factor based on the TX current and/or voltage and the matching current and/or voltage, dynamically controlling the transmitter (TX) signal envelope shape based on the Q factor. - View Dependent Claims (14, 15, 16, 17)
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18. A method for dynamically controlling transmitter (TX) signal envelope shape, the method comprising:
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sensing a matching current and/or voltage of an antenna and matching network; determining a Q (quality) factor based on the matching current and/or voltage as compared to a reference current and/or voltage level; dynamically controlling the transmitter (TX) signal envelope shape based on the Q factor, wherein dynamically controlling the transmitter (TX) signal envelope shape comprises; performing digital predistortion of the TX signal envelope, performing analog signal shaping of the TX signal envelope. - View Dependent Claims (19, 20)
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Specification