A capacitive sensing device includes an antenna electrode for emitting an alternating electric field in response to an alternating voltage caused in the antenna electrode and a control and evaluation circuit that includes a transimpedance amplifier configured to maintain the alternating voltage equal to an alternating reference voltage on a reference voltage node by injecting a current into the antenna electrode and to measure the current. The control and evaluation circuit includes a microcontroller and a multiplexer configured and arranged to switch the antenna electrode alternately to a current input of the transimpedance amplifier and to the alternating reference voltage node. The microcontroller is configured to control the multiplexer. The multiplexer and the transimpedance amplifier and a low-pass filter operatively connected to the transimpedance amplifier form together a synchronous rectifier arrangement. The current input node of the transimpedance amplifier is AC-coupled to the reference voltage node by a protection capacitor.
Capacitive sensing device
2017-08-08
Patent
Electronic Resource
English
IPC: | G01V Geophysik , GEOPHYSICS / B60N SEATS SPECIALLY ADAPTED FOR VEHICLES , Sitze besonders für Fahrzeuge ausgebildet / B62D MOTOR VEHICLES , Motorfahrzeuge / E05F DEVICES FOR MOVING WINGS INTO OPEN OR CLOSED POSITION , Vorrichtungen zum Bewegen der Flügel in die Offen- oder Schließstellung / G01D MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE , Anzeigen oder Aufzeichnen in Verbindung mit Messen allgemein / H03K PULSE TECHNIQUE , Impulstechnik |