US 9,753,138 B1 · Transducer measurement

Abstract

A transducer such as a translinear proportional-to-absolute-temperature sensor uses two amplifiers, where each amplifier is used in a variety of modes. The first amplifier generates a measurement voltage though feedback in an analog circuit. The second amplifier samples and integrates the measurement in a switched-capacitor mode, and the output is stored on a capacitor. Then the first amplifier is set to measure its offset. The offset is sampled and integrated by the second amplifier, and the output is stored on a second capacitor. Then the first and second amplifiers are set to buffer the voltages stored on the capacitors. The measurement can then be offset-adjusted by digital or analog means. The adjusted measurement is then available to be used for calibration of, e.g., an image sensor. Other transducers, such as pressure sensors, strain sensors, gyroscopes, magnetometers, accelerometers, and xyz positioning sensors may employ the same dual amplifier approach.

Claims20

Dependent claims

A method of deriving transducer measurement and an offset measurement, comprising:

sampling a first output of a first amplifier, where the first amplifier is set in a measurement feedback mode, to create a measurement sample;
integrating the measurement sample using a second amplifier, where the second amplifier is set in a switched capacitor mode, to create a measurement output voltage;
holding the measurement output voltage on a first holding capacitor;
sampling a second output of the first amplifier, where the first amplifier is set in a first buffering mode, to create an offset sample;
integrating the offset sample using the second amplifier in the switched capacitor mode to create an offset output voltage;
holding the offset output voltage on a second holding capacitor;
buffering the measurement output voltage on the first holding capacitor using the second amplifier, where the second amplifier is set in a second buffering mode, to create a final buffered measurement voltage;
and
buffering the offset output on the second holding capacitor using the first amplifier, where the first amplifier is set in a third buffering mode, to create a final buffered offset voltage.

6 more elements

A measurement system, comprising:

a first amplifier with configurable modes, the modes of the first amplifier comprising:
a measurement feedback mode,
an offset sampling mode, and
an offset buffering mode;
a second amplifier with configurable modes, the modes of the second amplifier comprising:
an input sampling mode,
an integration mode,
a measurement output hold mode,
an offset output hold mode,
a measurement buffering mode;
and
a digital state machine configured to manipulate the modes of the first and second amplifiers in controlled sequences, the sequences comprising:
a first sequence comprising setting the first amplifier in the measurement feedback mode, then setting the second amplifier to the input sampling mode, the integration mode, and the measurement output hold mode;
a second sequence comprising setting the first amplifier in the offset sampling mode, then setting the second amplifier to the input sampling mode, the integration mode, and offset output hold mode;
and
a third sequence comprising setting the first amplifier to the offset buffering mode and setting the second amplifier to the measurement buffering mode.

13 more elements

A depth camera system, comprising:

an image sensor;
a digital state machine comprising digital logic circuitry, a microprocessor, a microcontroller, or a field-programmable logic device;
an analog to digital converter;
a first amplifier with configurable modes and a second amplifier with configurable modes;
and
a temperature sensor comprising a translinear proportional-to-absolute-temperature transducer circuit;
where the modes of the first amplifier comprise
a measurement feedback mode,
an offset sampling mode, and
an offset buffering mode;
where the modes of the second amplifier comprise
an input sampling mode,
an integration mode,
a measurement output hold mode,
an offset output hold mode,
a measurement buffering mode;
and
where the digital state machine is configured to manipulate the modes of the first and second amplifiers in controlled sequences, the sequences comprising:
a first sequence comprising setting the first amplifier in the measurement feedback mode, then setting the second amplifier to the input sampling mode, the integration mode, and the measurement output hold mode;
a second sequence comprising setting the first amplifier in the offset sampling mode, then setting the second amplifier to the input sampling mode, the integration mode, and offset output hold mode;
and
a third sequence comprising setting the first amplifier to the offset buffering mode, setting the second amplifier to the measurement buffering mode, digitizing the buffered offset and the buffered measurement, and using the digitized buffered offset and measurement to calibrate a reading of the image sensor.

19 more elements

Dependencies are inferred from the claim text.

Transducer measurement

Life of this patent

Transducer measurement

Life of this patent

Abstract

Claims20