公开(公告)号：EP1790988A1

公开(公告)日：2007-05-30

申请号：EP05425842.1

申请日：2005-11-29

Applicant: STMicroelectronics S.r.l.

Inventor： Ungaretti, Tommaso ,  Lasalandra, Ernesto

IPC: G01P15/125

CPC classification number: G01P15/125 ,  G01P15/131

Abstract: A detection circuit (42) is provided with a differential capacitive sensor (1) and with an interface circuit (30) having a first sense input (7a) and a second sense input (7b), electrically connected to the differential capacitive sensor (1). Provided in the interface circuit are: a sense amplifier (12) connected at input to the first sense input and to the second sense input (7a, 7b) and supplying an output signal (V o ) related to a capacitive unbalancing (ΔC s ) of the differential capacitive sensor (1); and a common-mode control circuit (32), connected to the first sense input (7a) and to the second sense input (7b) and configured to control a common-mode electrical quantity present on the first sense input (7a) and on the second sense input (7b). The common-mode control circuit (32) is of a totally passive type and is provided with a capacitive circuit (34, 35), which is substantially identical to an equivalent electrical circuit of the differential capacitive sensor (1) and is driven with a driving signal V r ‾ in phase opposition with respect to a read signal (V r ) supplied to the differential capacitive sensor.