Nfc circuit switch
AssigneeSTMicroelectronics International N.V.
InventorMartin PROSSEGGER
Life of this patent
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Abstract
An NFC antenna selector circuit switch includes an antenna matching circuit having first and second output nodes coupled to an antenna. A first transistor couples a first NFC signal input node to the matching circuit, and a second transistor couples a second NFC signal input node to the matching circuit. Controlling nodes of the first and second transistors are coupled together at a first node, where the first node is coupled to a first voltage rail via a first resistor. A third transistor couples the first node to ground. A first voltage is applied to the first voltage rail. The first voltage has absolute value greater than a maximum voltage present between first and second NFC signal input nodes plus a transistor threshold voltage.
Claims19
An NFC antenna selector circuit switch, comprising:
- an antenna matching circuit having a first output node and a second output node configured to be coupled to terminals of an antenna;
- a first transistor having a first conduction node coupled to the antenna matching circuit and a second conduction node coupled to a first NFC signal input node;
- a second transistor having a first conduction node coupled to the antenna matching circuit and a second conduction node coupled to a second NFC signal input node;
- wherein controlling nodes of the first and second transistors are coupled together to a first node, the first node being coupled to a first voltage rail via a first resistor;
- and
- a third transistor having a first conduction node couple to the first node and a second conduction node coupled to ground;
- wherein a first voltage at the first voltage rail has an absolute value greater than a maximum voltage present between first and second NFC signal input nodes plus a threshold voltage of one of the first or second transistors.
A functioning method of an NFC antenna selector circuit switch having an antenna matching circuit having first and second output nodes configured to be coupled to an antenna;
- a first transistor coupling a first NFC signal input node to the matching circuit;
- a second transistor coupling a second NFC signal input node to the matching circuit, wherein controlling nodes of the first and second transistors are coupled together to a first node, the first node being coupled to a first voltage rail via a first resistor;
- and a third transistor coupling the first node to ground, the method comprising:
- applying a first voltage to the first voltage rail that has an absolute value greater than a maximum voltage present between the first and second NFC signal input nodes plus a threshold voltage of one of the first or second transistors.
Dependencies are inferred from the claim text.