Method and device for active load modulation by inductive coupling
First Claim
1. A method of transmitting data by inductive coupling and active load modulation, the method comprising:
- receiving an antenna signal using an inductive antenna circuit in the presence of an alternating external magnetic field;
extracting from the antenna signal a first periodic signal;
producing a second periodic signal using a synchronous oscillator having a synchronization input receiving the first periodic signal, the synchronous oscillator having a synchronous oscillation mode set in phase with the first periodic signal and a free oscillation mode;
applying to the antenna circuit bursts of the second periodic signal of a duration less than that of one bit of the transmitted data to generate an active load modulation magnetic field;
placing the synchronous oscillator in the synchronous oscillation mode before each application of a burst of the second periodic signal to the antenna circuit; and
placing the synchronous oscillator in the free oscillation mode during the application of a burst of the second periodic signal to the antenna circuit, such that the synchronous oscillator is resynchronized to the first periodic signal at least once at each transmission of a data bit.
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Abstract
A data emission/reception device by inductive coupling includes an inductive antenna circuit in which an antenna signal appears, a mechanism configured to for extracting a first periodic signal from the antenna signal, a synchronous oscillator receiving the first periodic signal and supplying a second periodic signal, and an active load modulation circuit configured to apply bursts of the second periodic signal to the antenna circuit. The device is configured to place the oscillator in the synchronous oscillation mode before each application of a burst of the second periodic signal to the antenna circuit, then place the oscillator in the free oscillation mode.
21 Citations
16 Claims
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1. A method of transmitting data by inductive coupling and active load modulation, the method comprising:
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receiving an antenna signal using an inductive antenna circuit in the presence of an alternating external magnetic field; extracting from the antenna signal a first periodic signal; producing a second periodic signal using a synchronous oscillator having a synchronization input receiving the first periodic signal, the synchronous oscillator having a synchronous oscillation mode set in phase with the first periodic signal and a free oscillation mode; applying to the antenna circuit bursts of the second periodic signal of a duration less than that of one bit of the transmitted data to generate an active load modulation magnetic field; placing the synchronous oscillator in the synchronous oscillation mode before each application of a burst of the second periodic signal to the antenna circuit; and placing the synchronous oscillator in the free oscillation mode during the application of a burst of the second periodic signal to the antenna circuit, such that the synchronous oscillator is resynchronized to the first periodic signal at least once at each transmission of a data bit. - View Dependent Claims (2, 3, 4, 5)
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6. A data transmission/reception device by inductive coupling comprising:
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an inductive antenna circuit in which an antenna signal appears in the presence of an alternating external magnetic field; a clock circuit configured to extract a first periodic signal from the antenna signal; a synchronous oscillator having a synchronization input receiving the first periodic signal, supplying a second periodic signal, the synchronous oscillator having a synchronous oscillation mode set in phase with the first periodic signal and a free oscillation mode; and an active load modulation circuit configured to apply bursts of the second periodic signal of a duration of less than that of one bit of the transmitted data to the antenna circuit and to generate an active load modulation magnetic field, wherein the device is configured to; place the synchronous oscillator in the synchronous oscillation mode before each application of a burst of the second periodic signal to the antenna circuit, and place the synchronous oscillator in the free oscillation mode during the application of a burst of the second periodic signal to the antenna circuit, such that the synchronous oscillator is resynchronized to the first periodic signal at least once at each transmission of a data bit. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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Specification