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US 8,947,107 B2Granted
Capacitance measurement of high voltage device
AssigneeSemtech Corporation
InventorMichel Alain Chevroulet
Life of this patent
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Abstract
Described herein are systems and methods that facilitate the measurement of the capacitance of high voltage devices while shielding an active device involved in the measurement from the high voltage. The systems and methods employ capacitors to store the high voltage such that the active device does not experience the high voltage. Placement of a reset device ensures that the active device is shielded from the high voltage.
Claims20
A system, comprising:
- an amplifier comprising a positive input, a negative input, and an output;
- a first capacitor connected to the negative input of the amplifier and to an external device with an unknown capacitance, wherein the first capacitor stores a first voltage;
- a second capacitor connected to the output of the amplifier and to the external device, wherein the second capacitor stores the first voltage;
- a voltage source device that supplies a second voltage to the positive input of the amplifier;
- a reset device that connects the output of the amplifier and the negative input of the amplifier;
- and
- a detector device that measures a change in the output voltage of the amplifier as a function of a change in the second voltage supplied by the voltage source and function of the unknown capacitance of the external device,
- wherein the first voltage is higher than the second voltage.
5 more elements
A method, comprising:
- storing a first voltage on an external device with an unknown capacitance, on a first capacitor between a negative input of an amplifier and the external device, and on a second capacitor connected between the output of the amplifier and the external device;
- applying a second voltage to a positive input of the amplifier;
- driving a voltage of the output of the amplifier and a voltage of the negative input of the amplifier to the second voltage via a reset device;
- modifying the second voltage applied at the positive input of the amplifier;
- measuring a voltage change of the output of the amplifier that is proportional to the unknown capacitance and to the voltage change applied at the positive input of the amplifier,
- wherein the first voltage is higher than the second voltage.
3 more elements
A capacitance measuring circuit, comprising:
- an amplifier comprising a positive input, a negative input, and an output;
- a first capacitor connected to the negative input of the amplifier and to an external device with an unknown capacitance, wherein the first capacitor stores a first voltage;
- a second capacitor connected to the output of the amplifier and to the external device, wherein the second capacitor stores the first voltage;
- and
- a reset device that connects the output of the amplifier and the negative input of the amplifier and facilitates driving the output of the amplifier and the negative input of the amplifier to a second voltage supplied by a voltage source device to the positive input of the amplifier,
- wherein a change in the output voltage of the amplifier as a result of a change of voltage supplied by the voltage source is a function of the unknown capacitance of the external device, and
- wherein the first voltage is higher than the second voltage.
4 more elements
Dependencies are inferred from the claim text.