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US 10,770,891 B2Granted
Protection of an NFC router against overvoltage
AssigneeSTMicroelectronics (Rousset) SAS
InventorAlexandre Tramoni
Life of this patent
Estimating the term…
Abstract
The invention relates to a device for protecting a near field communication router against possible over-voltages picked up by an antenna. The device includes two voltage-limiter elements between terminals of the antenna and a ground. A circuit detects the presence of an electromagnetic field in the vicinity of an operating frequency of the router, and controls the limiter elements, the limiter elements being active by default.
Claims25
A device comprising:
- a first antenna terminal;
- a second antenna terminal;
- a ground terminal;
- a near field communication circuit coupled to the first and second antenna terminals, the near field communication circuit configured to operate at an operating frequency;
- a first voltage-limiter coupled between the first antenna terminal and the ground terminal;
- a second voltage-limiter coupled between the second antenna terminal and the ground terminal;
- and
- a controller configured to detect, at the first and second antenna terminals, an electromagnetic field having a frequency that corresponds to the operating frequency, and to control the first and second voltage-limiters based upon the detected electromagnetic field, wherein the first and second voltage-limiters are active by default and wherein the controller is configured to deactivate the first and second voltage-limiters after detecting that the frequency corresponds to the operating frequency of the near field communication circuit.
5 more elements
A device comprising:
- a first antenna terminal;
- a second antenna terminal;
- a ground terminal;
- a near field communication circuit coupled to the first and second antenna terminals;
- a first voltage-limiter coupled between the first antenna terminal and the ground terminal;
- a second voltage-limiter coupled between the second antenna terminal and the ground terminal;
- a field detector coupled to the first and second antenna terminals;
- a reference clock generator;
- and
- a comparator with a first input coupled to an output of the field detector, a second input coupled to an output of the reference clock generator, and an output coupled to a control input of the first voltage-limiter and to a control input of the second voltage-limiter.
7 more elements
A near field communication device comprising:
- an antenna;
- a near field communication circuit coupled to the antenna, the near field communication circuit configured to operate at a first frequency;
- a first switch coupled between a first terminal of the antenna and a ground terminal,
- a second switch coupled between a second terminal of the antenna and the ground terminal;
- and
- a controller configured to extract a clock signal from a signal received at the antenna, to compare the extracted clock signal with a reference clock signal to produce a comparison result, and to control the first and second switches based on the comparison result.
3 more elements
A method of overvoltage protection for a contactless communication device, the method comprising:
- using a voltage limiter to limit a voltage across terminals of an antenna coupled to the contactless communication device;
- detecting an electromagnetic field having a first frequency, the electromagnetic field being detected at the terminals of the antenna;
- after detecting the electromagnetic field having the first frequency, turning off the voltage limiter;
- and
- while the voltage limiter is off, receiving a signal having the first frequency at the contactless communication device.
2 more elements
Dependencies are inferred from the claim text.