| 摘要 |
PCT No. PCT/FR90/00961 Sec. 371 Date Aug. 28, 1992 Sec. 102(e) Date Aug. 28, 1992 PCT Filed Dec. 28, 1990 PCT Pub. No. WO91/09812 PCT Pub. Date Jul. 11, 1991.A circuit for measuring variations in the capacitance of a variable capacitor forming part of a sensor includes an oscillator which generates an alternating signal which is supplied to two branches of a detection bridge. The first branch includes the variable capacitor connected in series with a variable capacitance diode. The second branch includes a capacitor connected in series with a variable capacitance diode. A differential stage has each of its in puts connected to the common point of a respective one of the branches. Synchronous demodulation means connected to the oscillator, are connected to the output of the differential stage for delivering a DC unbalance voltage Ve which is injected by a feedback line to the common point of the first branch, thereby continuously balancing the detection bridge.
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