Bridge-based impedance sensor system
AssigneeAnalog Devices, Inc.
InventorsIsaac Chase Novet, Steven J. Decker
Life of this patent
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Abstract
An impedance sensing circuit includes three impedance elements and a sensing element arranged in a bridge configuration. A first input terminal is coupled to two of the impedance elements to apply a stimulus signal. In a mutual-sensing mode, a second input terminal is coupled to the third impedance element and the sensing impedance element to apply an opposite phase stimulus signal. The impedance sensing circuit may be configured in a self-sensing mode, in which the opposite phase stimulus signal is decoupled from the third impedance element and the sensing impedance element. At least one of the impedance elements is variable and may be adjusted to balance an offset impedance load on the sensing element.
Claims20
A sensor system comprising:
- an impedance bridge comprising a first impedance element, a second impedance element, a third impedance element, and a coupling network arranged in a bridge configuration;
- a first input terminal coupled to the first impedance element and the second impedance element and configured to apply a first stimulus signal to the impedance bridge;
- a second input terminal coupled, in a first mode, to the coupling network and the third impedance element to apply a second stimulus signal to the impedance bridge;
- and
- at least one switch coupled to the second input terminal, the at least one switch controllable to decouple the second stimulus signal from the coupling network and the third impedance element in a second mode.
A method comprising:
- receiving a first instruction to configure a sensor system in a first mode, the sensor system comprising a first impedance element, a second impedance element, a third impedance element, and a coupling network arranged in a bridge configuration;
- in response to the first instruction, coupling the coupling network to a first electrode and a second electrode;
- receiving a second instruction to configure the sensor system in a second mode;
- and
- in response to the second instruction, decoupling the coupling network from the second electrode.
Dependencies are inferred from the claim text.