Capacitive Sensor Test

Abstract

The present invention relates to capacitive sensor testing. Sensor devices and methods are provided in which a test signal is applied to a capacitive sensor. Furthermore, a bias voltage is applied to the capacitive sensor via a high impedance component. The path used to apply the test signal excludes high impedance components. Using the test signal, in some implementations, a capacitance imbalance of the capacitive sensor can be detected.

Description

technical field [0001] The present application relates to apparatus and methods related to the testing of capacitive sensors. Background technique [0002] A capacitive sensor (also known as a capacitive transducer) responds to a physical quantity to be measured by a change in the sensor's capacitance, which in turn can be detected by an appropriate readout circuit. Examples of such capacitive sensors include pressure sensors or microphones. Recently, such capacitive sensors have increasingly been implemented as microelectromechanical systems (MEMS), where the sensor itself, together with additional circuitry, may be implemented eg on a single silicon chip die. An implementation with two or more separate dies (eg, one die with mechanical sensors and one die with electronic circuitry). In such cases, the separate dies may be wire bonded or connected, for example, using other techniques such as through silicon vias (TSVs). [0003] Such capacitive sensors typically include ...

AI Technical Summary

Problems solved by technology

While many of these schemes are quite suitable for sensors being used in constant voltage biasing schemes, they may not be well suited for constant charge biasing schemes

In particular, in the constant charge biasing scheme, the high impedance used, which may be in the GΩ range or higher, actually acts as a filter with a relatively slow time constant, which makes it possible to apply a suitable test signal without disturbing the sensor practical operation becomes difficult

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