Accurate persistent nodes
First Claim
Patent Images
1. A timing circuit, comprising:
- a power capture circuit for capturing energy from a power source; and
a counter circuit coupled to the power capture circuit, the counter circuit providing a count that represents a progression of time,wherein the power capture circuit includes a differential amplifier and a capacitance,wherein the differential amplifier compares a voltage level of the power source to a voltage level of a node formed on the capacitance;
wherein if the voltage level of the power source is greater than a specified voltage level, the differential amplifier clamps the node to the power source.
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Abstract
A timing circuit that can function as an accurate persistent node in an RFID tag includes a power capture circuit for capturing power from a power source, and a counter circuit that provides a count representing a progression of time. The count can then be compared to a reference value representing a time constant of the circuit.
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Citations
42 Claims
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1. A timing circuit, comprising:
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a power capture circuit for capturing energy from a power source; and a counter circuit coupled to the power capture circuit, the counter circuit providing a count that represents a progression of time, wherein the power capture circuit includes a differential amplifier and a capacitance, wherein the differential amplifier compares a voltage level of the power source to a voltage level of a node formed on the capacitance;
wherein if the voltage level of the power source is greater than a specified voltage level, the differential amplifier clamps the node to the power source. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32)
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33. A timing circuit, comprising:
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a power capture circuit for capturing power from a power source, wherein the power capture circuit further comprises a subcircuit for comparing a voltage level of the power source to a voltage level of a node formed on the capacitance;
wherein if the voltage level of the power source is greater than a predetermined voltage level, the differential amplifier clamps the node to the power source, wherein if the voltage level of the power source drops below a level of the capacitance stored on the node, the node is isolated from the power source; anda counter circuit coupled to the power capture circuit, the counter circuit providing a count that represents a progression of time, wherein the count is compared to a reference value representing a time constant of the circuit.
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34. A method for generating a timing signal, comprising:
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generating a count that represents a progression of time using a counter circuit coupled to a power capture circuit, the power capture circuit being for capturing energy from a power source, wherein the power capture circuit includes a differential amplifier and a capacitance, wherein the differential amplifier compares a voltage level of the power source to a voltage level of a node formed on the capacitance;
wherein if the voltage level of the power source is greater than a specified voltage level, the differential amplifier clamps the node to the power source;comparing the count to a reference value representing a time constant of the circuit; and outputting a timing signal if the count matches the reference value. - View Dependent Claims (35, 36, 37)
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38. A circuit, comprising:
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an input node; a storage node for storing an analog signal; a coupling mechanism for selectively coupling the input and storage nodes to each other; a control mechanism for controlling the coupling means responsive to the signal difference between the input node and the storage node; a power capture circuit for capturing energy from a power source; and a counter circuit coupled to the power capture circuit, the counter circuit providing a count that represents a progression of time, wherein the power capture circuit includes a differential amplifier and a capacitance, wherein the differential amplifier compares a voltage level of the power source to a voltage level of a node formed on the capacitance;
wherein if the voltage level of the power source is greater than a specified voltage level, the differential amplifier clamps the node to the power source. - View Dependent Claims (39, 40, 41, 42)
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Specification