Circuit and method to facilitate threshold voltage extraction and facilitate operation of a capacitor multiplier
First Claim
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1. A system for extracting a threshold voltage, comprising:
- a first MOSFET stage including an input operative to receive a first input current, and a gate node electrically coupled to the input thereof;
a second MOSFET stage including an input operative to receive a second input current and a gate node; and
a voltage divider coupled between the input of the second MOSFET stage and the gate node of the first MOSFET stage, the voltage divider also having an intermediate output node coupled to the gate node of the second MOSFET stage, such that an output voltage at the input of the second MOSFET stage is approximately equal to the threshold voltage for at least one of the first and second MOSFET stages.
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Abstract
A system and method to extract a threshold voltage for a MOSFET include first and second stages, which include inputs that receive functionally related input currents, are connected to each other. The first stage includes a second input that is coupled to a corresponding input of the second stage through part of a voltage divider. Another part of the voltage divider is coupled between an internal gate node and the input of the second stage that receives the respective input current. The input of the second stage that receives the respective input current also provides an output voltage substantially equal to the threshold voltage for one or both of the MOSFETs.
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Citations
33 Claims
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1. A system for extracting a threshold voltage, comprising:
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a first MOSFET stage including an input operative to receive a first input current, and a gate node electrically coupled to the input thereof;
a second MOSFET stage including an input operative to receive a second input current and a gate node; and
a voltage divider coupled between the input of the second MOSFET stage and the gate node of the first MOSFET stage, the voltage divider also having an intermediate output node coupled to the gate node of the second MOSFET stage, such that an output voltage at the input of the second MOSFET stage is approximately equal to the threshold voltage for at least one of the first and second MOSFET stages. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A system, comprising:
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a first system comprising;
a first MOSFET stage including an input operative to receive a first input current, and a gate node electrically coupled to the input thereof;
a second MOSFET stage including an input operative to receive a second input current and a gate node;
a voltage divider coupled between the input of the second MOSFET stage and the gate node of the first MOSFET stage, the voltage divider also having an intermediate output node coupled to the gate node of the second MOSFET stage, such that an output voltage at the input of the second MOSFET stage is approximately equal to the threshold voltage for at least one of the first and second MOSFET stages; and
a second system for extracting a threshold voltage coupled to the first system for extracting a threshold voltage to provide a stacked threshold voltage extraction system having an output that is an integer multiple of the threshold voltage of the second system.
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13. A system, comprising:
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a first MOSFET stage including an input operative to receive a first input current, and a gate node electrically coupled to the input thereof;
a second MOSFET stage including an input operative to receive a second input current and a gate node;
a voltage divider coupled between the input of the second MOSFET stage and the gate node of the first MOSFET stage, the voltage divider also having an intermediate output node coupled to the gate node of the second MOSFET stage, such that an output voltage at the input of the second MOSFET stage is approximately equal to the threshold voltage for at least one of the first and second MOSFET stages; and
a capacitor multiplier including a first input that receives the output voltage at the input of the second MOSFET stage and a second input that receives a bias current, such that a startup offset for the capacitor multiplier is mitigated when the bias current is applied to the second input. - View Dependent Claims (14, 15)
first and second stages coupled together at a common node, the first input of the capacitor multiplier being associated with the common node so that a voltage approximately equal to the threshold voltage is at the common node; and
a feedback capacitor coupled between an output of the capacitor multiplier and the second input of the capacitor multiplier.
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15. The system of claim 14, the first input current and the second input current having values proportional to each other.
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16. A system for extracting a threshold voltage, comprising:
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a first MOSFET having a drain connected to receive a first input current, a gate electrically coupled to the drain, and a source coupled to a reference potential;
a second MOSFET having a gate, source and drain, the drain being connected to receive a second input current, the source being coupled to the reference potential;
a first part of a voltage divider being coupled between the gate of the first MOSFET and the gate of the second MOSFET;
a second part of the voltage divider being coupled between the gate and the drain of the second MOSFET, such that an output voltage at drain of the second MOSFET is approximately equal to the threshold voltage for at least one of the first and second MOSFETs. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24)
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25. A system, comprising:
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a first system comprising;
a first MOSFET having a drain connected to receive a first input current, a gate electrically coupled to the drain, and a source coupled to a reference potential;
a second MOSFET having a gate, source and drain, the drain being connected to receive a second input current, the source being coupled to the reference potential;
a first part of a voltage divider being coupled between the gate of the first MOSFET and the gate of the second MOSFET;
a second part of the voltage divider being coupled between the gate and the drain of the second MOSFET, such that an output voltage at drain of the second MOSFET is approximately equal to the threshold voltage for at least one of the first and second MOSFETs; and
a second system for extracting a threshold voltage coupled to the first system for extracting a threshold voltage to provide a stacked threshold voltage extraction system having an output that approximates an integer multiple of the threshold voltage of the second system.
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26. A system, comprising:
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a first MOSFET having a drain connected to receive a first input current, a gate electrically coupled to the drain, and a source coupled to a reference potential;
a second MOSFET having a gate, source and drain, the drain being connected to receive a second input current, the source being coupled to the reference potential;
a first part of a voltage divider being coupled between the gate of the first MOSFET and the gate of the second MOSFET;
a second part of the voltage divider being coupled between the gate and the drain of the second MOSFET, such that an output voltage at drain of the second MOSFET is approximately equal to the threshold voltage for at least one of the first and second MOSFETs;
a capacitor multiplier circuit comprising first and second amplifier stages coupled together at a common node, the first stage having a first input that receives a bias current; and
the output voltage from the drain of the second MOSFET being applied to the capacitor multiplier circuit so that voltage approximately equal to the threshold voltage is at the common node, such that a startup offset for the capacitor multiplier circuit is mitigated as the bias current is applied to the first input of the capacitor multiplier circuit.
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27. A capacitor multiplier system, comprising:
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a threshold voltage extraction system that provides an output having a value functionally related to a threshold voltage; and
a capacitor multiplier circuit comprising a first and second stages coupled together at a common gate node, the first stage having a first input that receives an input current, a feedback capacitor being coupled between an output of the second stage of the capacitor multiplier circuit and the first input, the output from the threshold voltage extraction system being provided to a second input of the capacitor multiplier circuit that is operatively connected with the common gate node, such that the threshold voltage is provided to at the common gate node and a startup offset for the capacitor multiplier circuit is mitigated as the input current is applied to the first input. - View Dependent Claims (28, 29, 30)
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31. A method for extracting a threshold voltage for a MOSFET device having a gate, source and drain, the method comprising:
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connecting gates of first and second stages through a first part of a voltage divider, each stage including a respective MOSFET device;
saturating the MOSFET device of the first stage;
providing bias current to an input of the first stage;
providing bias current to an input of the second stage, the input of the second stage being connected to the gate of the second stage through a second part of the voltage divider;
saturating the MOSFET device of the second stage, such that a voltage at the input of the second stage corresponds to the threshold voltage. - View Dependent Claims (32)
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33. A method for employing a MOSFET device having a gate, source and drain, the method comprising:
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connecting gates of first and second stages through a first part of a voltage divider, each stage including a respective MOSFET device;
saturating the MOSFET device of the first stage;
providing bias current to an input of the first stage;
providing bias current to an input of the second stage, the input of the second stage being connected to the gate of the second stage through a second part of the voltage divider;
saturating the MOSFET device of the second stage, such that a voltage at the input of the second stage corresponds to the threshold voltage;
wherein the bias current to the input of the first stage is proportional to the bias current to the input of the second stage; and
providing the voltage at the output of the second stage to an input of a capacitor multiplier, such that the threshold voltage is applied to an internal node of the capacitor multiplier and a startup offset of the capacitor multiplier is mitigated.
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Specification