Calibration of Inverting Amplifier Based Impedance Analyzers
AssigneeTexas Instruments Incorporated
InventorCharles Kasimer Sestok, IV
Life of this patent
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Abstract
A circuit for measuring an impedance of a device under test (DUT). The circuit includes: (i) circuitry for generating a stimulus wave at a stimulus frequency; (ii) an amplifier circuit coupled to the DUT to present a response signal from the DUT in response to the stimulus wave; (iii) switching circuitry for selectively coupling, between the stimulus wave and an input to the amplifier, either the DUT, a first calibration impedance, or a second calibration impedance. With the switching functionality, calibrations are performed so to provide a measure of impedance of the DUT in response to the plural calibrations.
Claims20
A circuit for measuring an impedance of a device under test (DUT), comprising:
- circuitry for generating a stimulus wave at a stimulus frequency;
- an amplifier circuit coupled to the DUT to present a response signal from the DUT in response to the stimulus wave;
- switching circuitry for selectively coupling, between the stimulus wave and an input to the amplifier, either the DUT, a first calibration impedance, or a second calibration impedance;
- and
- processor circuitry programmed to sample a signal responsive to the response signal, wherein the processor is programmed to:
- in a first iteration, with the switching circuitry selectively coupling the first calibration impedance between the stimulus wave and an input to the amplifier, sampling a first signal responsive to the response signal;
- in a second iteration, with the switching circuitry selectively coupling the second calibration impedance between the stimulus wave and an input to the amplifier, sampling a second signal responsive to the response signal;
- in a third iteration, with the switching circuitry selectively coupling the DUT between the stimulus wave and an input to the amplifier, sampling a third signal responsive to the response signal;
- and
- wherein the processor circuitry is further programmed to provide a measure of impedance of the DUT in response to the first signal responsive to the response signal, the second signal responsive to the response signal, and the third signal responsive to the response signal.
A method of measuring an impedance of a device under test (DUT), comprising:
- generating a stimulus wave at a stimulus frequency;
- coupling a signal responsive to the stimulus wave to a first terminal of the DUT;
- selectively coupling, between the stimulus wave and an input to an amplifier, either the DUT, a first calibration impedance, or a second calibration impedance, to present a response signal from the selective coupling in response to the stimulus wave;
- and
- performing the steps of:
- in a first iteration, coupling the first calibration impedance between the stimulus wave and an input to the amplifier and sampling a first signal responsive to the response signal;
- in a second iteration, coupling the second calibration impedance between the stimulus wave and an input to the amplifier and sampling a second signal responsive to the response signal;
- in a third iteration, coupling the DUT between the stimulus wave and an input to the amplifier and sampling a third signal responsive to the response signal;
- and
- providing a measure of impedance of the DUT in response to the first signal responsive to the response signal, the second signal responsive to the response signal, and the third signal responsive to the response signal.
Dependencies are inferred from the claim text.