Patent ID: 6498501
Filing Date: 2002-12-24
Classification: G01H,G01L,G01P

Abstract:
A measuring circuit, comprising:a transducer comprising a transducer element and first and second series connected signal injection capacitors connected in parallel with the transducer, a shielded container for the transducer element and the first and second signal injection capacitors, the shielded container having a ground connection and three terminals, two of the terminals comprising first and second output terminals for outputting first and second output signals and the third terminal comprising at least one input terminal coupled to a common node between the capacitors; a measuring unit; connecting means having first and second input terminals and first and second output terminals, the first and second input terminals of the connecting means being connected to the first and second output terminals of the transducer and the connecting means delivering the first and second output signals on the first and second output terminals of the transducer to the first and second output terminals of the connecting means; the measuring unit comprising: a) a first amplifier having first and second input terminals connected, respectively, to the first and second output terminals of the connecting means for generating an output signal which is a function of the sum of the output signals present on the first and second output terminals of the connecting means; b) a second amplifier having first and second input terminals connected, respectively, to the first and second output terminals of the connecting means for generating an output signal which is a function of the difference of the output signals present on the first and second output terminals of the connecting means; and c) a generator for applying an auxiliary signal to said at least one input terminal of the transducer to test the operation of the measuring circuit.