Cambridge Silicon Radio Limited

Qualcomm Technologies International, Ltd.

Shyam Patel

Anthony Lawrence McFarthing

Zern Tay

A near field communications apparatus comprising a signal source, a transmit antenna and means for detecting a change in the input impedance of the transmit antenna to detect the presence of a device which is compatible with the apparatus.

Near field communications apparatus

The present application relates to a near field communications (NFC) device having an antenna which is coupled to a load. When in the presence of an active NFC reader or similar device, the antenna generates an electromotive force (EMF), which serves as an input signal to the load. A variable potential divider is included to vary the voltage of the input signal to the load, so that if a potentially damaging over-voltage condition exists the voltage of the input signal to the load can be reduced to a safe level. The variable potential divider may be composed of an effective source impedance and an effective impedance of the load, and the impedance of the impedance matching network may be variable by means of a variable capacitance and/or a variable resistance.

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Cambridge, United Kingdom

Shyam Patel