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Capacitive interface circuit for low power sensor system

A sensor signal, capacitive sensor technology, applied in the field of sensor interface circuits, can solve problems such as power reduction

Active Publication Date: 2009-10-28
MEDTRONIC INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Giving up kT / C noise allows lower interface clocks and results in reduced power

Method used

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  • Capacitive interface circuit for low power sensor system
  • Capacitive interface circuit for low power sensor system
  • Capacitive interface circuit for low power sensor system

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Embodiment Construction

[0022] [0020] This disclosure describes capacitive interface circuits for low power sensor systems. The capacitive interface circuit is configured to enable very low noise sensing with high resolution and low power using capacitive based sensors such as microelectromechanical systems (MEMS) based sensors. Capacitive interface circuits use differential amplifiers and correlated triple sampling (CTS) to reduce kT / C noise and flicker (1 / f) noise and to suppress amplifier offset and drift. The capacitive interface circuit may further include an output stage that reduces glitches in the output signal by allowing transients in the output of the amplifier to settle. In this way, the circuit can be used in low power systems to produce a stable, low noise output.

[0023] [0021] Capacitive interface circuits may be configured to process signals from sensing elements in MEMS-based sensors, such as accelerometers, gyroscopes, pressure sensors, humidity sensors, and the like. Exemplary ...

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Abstract

This disclosure describes a capacitive interface circuit for a low power system. The capacitive interface circuit is configured to achieve very low noise sensing of capacitance-based transducers, such as a micro-electro-mechanical system (MEMS)-based sensor, with high resolution and low power. The capacitive interface circuit uses a differential amplifier and correlated triple sampling (CTS) to substantially eliminate, or at least reduce, kT / C noise, as well as amplifier offset and flicker (1 / f) noise, from the output of the amplifier. The capacitive interface circuit may further include an output stage that reduces glitching, i.e., clock transients, in the output signal by allowing transients in the amplifier output to settle. In this manner, the circuit can be used in a low power system to produce a stable, low-noise output.

Description

technical field [0001] [0001] The present invention relates to sensor interface circuits, and more particularly to capacitive interface circuits for low power sensor systems. Background technique [0002] [0002] In micromechanical systems, such as microelectromechanical systems (MEMS) sensors, variable capacitors are used as an interface between sensors, such as accelerometers, gyroscopes, pressure sensors, humidity sensors, or other types of micro mechanical sensor. Such sensors have a wide variety of applications, including industrial monitoring, environmental monitoring, and / or physiological monitoring. Physiological monitoring has various biomedical applications including posture, activity, pace, venous pressure, intracranial pressure, heart sounds, and more. [0003] [0003] In an accelerometer, for example, a capacitive plate may be formed by fingers coupled to a beam structure of a proof mass and designated fingers coupled to an inertial frame. The set of fingers in...

Claims

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Application Information

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IPC IPC(8): G01D5/24
CPCG01D5/24
Inventor T·J·丹尼森
Owner MEDTRONIC INC
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