Knowles Electronics, Inc.

Ams International Ag

Rene Scheuner

Mark Niederberger

Colin Steele

Thomas Christen

Thomas Froehlich

Lukas Perktold

Duy-Dong Pham

An arrangement () to calibrate a capacitive sensor interface () includes a capacitive sensor () having a capacitance (cmem, cmemsp, cmemsm) and a charge storing circuit () having a changeable capacitance (cdum, cdump, cdumm). A test circuit () applies a test signal (vtst) to the capacitive sensor () and the charge storing circuit (). An amplifier circuit () has a first input connection (E) coupled to the capacitive sensor () and a second input connection (E) coupled to the charge storing circuit (). The amplifier circuit () provides an output signal (Vout) in dependence on a first input signal (&#x394;Verr) applied to the first input connection (E) and a second input signal (&#x394;Verr) applied to the second input connection (E). A control circuit () is configured to trim the capacitance (cdum, cdump, cdumm) of the charge storing circuit () such that the level of the output signal (Vout) tends to the level of zero.

Arrangement to calibrate a capacitive sensor interface

A MEMS sensor () comprises a MEMS transducer () being coupled to a MEMS interface circuit (). The MEMS interface circuit () comprises a bias voltage generator (), a differential amplifier (), a capacitor () and a feedback control circuit (). The bias voltage generator () generates a bias voltage (Vbias) for operating the MEMS transducer. The variable capacitor () is connected to one of the input nodes (I) of the differential amplifier (). At least one of the output nodes (A, A) of the differential amplifier is coupled to a base terminal (T) of an output filter () of the bias voltage generator (). Any disturbing signal from the bias voltage generator () is a common-mode signal that is divided equally on the input nodes (I, I) of the differential amplifier () and is therefore rejected.

MEMS sensor

Growing community of inventors

Winterthur, Switzerland

Rene Scheuner