Subset selection of RFID tags using light
First Claim
1. A circuit to provide a direct current (DC) output voltage, comprising:
- a first bias circuit to receive a radio frequency (RF) input;
a first voltage multiplier circuit coupled to the first bias circuit, the first voltage multiplier circuit comprising a first transistor used as a rectifying element to generate the DC output voltage, the first bias circuit to generate a first bias voltage to reduce a turn on threshold voltage of the first transistor.
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Accused Products
Abstract
Methods and apparatuses for selecting a subset of RFID tags are provided in some embodiments. These methods and apparatuses utilize the susceptibility to light by persistent nodes found in passive tags. Light can be used to intentionally reduce persistence times in a particular subset tags or even an individual tag. Then, persistent nodes can be used as a selection criterion to distinguish previously illuminated tags from non-illuminated tags. In other embodiments, a power circuit receives a RF input source and generates a direct current (DC) output voltage. The circuit includes a bias circuit to supply a gate to source bias, which is independent of the DC output voltage. The circuit further includes a voltage multiplier circuit that is coupled to the bias circuit. The voltage multiplier circuit has MOS transistors with one transistor to receive the gate to source bias.
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Citations
19 Claims
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1. A circuit to provide a direct current (DC) output voltage, comprising:
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a first bias circuit to receive a radio frequency (RF) input; a first voltage multiplier circuit coupled to the first bias circuit, the first voltage multiplier circuit comprising a first transistor used as a rectifying element to generate the DC output voltage, the first bias circuit to generate a first bias voltage to reduce a turn on threshold voltage of the first transistor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A radio frequency identification (RFID) tag comprising:
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an RF circuitry to receive and transmit RF signals to a RFID reader; a processing logic coupled to the RF circuitry; and a first circuit comprising at least one transistor coupled to the RF circuitry, the first circuit being configured to be relatively insensitive to light radiation by isolating a base region of the at least one transistor in an isolation well. - View Dependent Claims (11, 12, 13, 14, 15)
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16. A radio frequency identification (RFID) tag comprising:
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a RF circuitry to receive and transmit RF signals to an RFID reader; a processing logic coupled to the RF circuitry; and an oscillator coupled to the RF circuitry, the oscillator being configured to be relatively insensitive to light radiation, the oscillator configured to vary its oscillation frequency with temperature, wherein the oscillation frequency is used to determine the temperature of the tag. - View Dependent Claims (17, 18, 19)
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Specification