Abstract: In an interface circuit connected to a capacitance type sensor having two sets of capacitors C1 and C2 whose capacitances are varied, this interface circuit is equipped with an OP amplifier A1 where a feedback/sampling capacitor C3 is connected between its output terminal and its inverting input terminal; and a holding capacitor C4 connected between a non-inverting terminal of the OP-amplifier A1 and a reference voltage source; one ends of the respective capacitors C1, C2, C3 are connected to the inverting input terminal of the OP amplifier A1; at timing .phi.1 of a switching cycle, the other ends of the respective capacitors C1, C2 are connected to a power source and the capacitor C3 is shortcircuited; at timing .phi.

Abstract: In a switched-capacitor type interface circuit connected to a capacitive sensor having two capacitors (C1, C2) whose value is variable, the interface circuit includes an operational amplifier (A1) with an output terminal and an inverting input terminal between which a feedback/sampling capacitor (C3) is connected, and a holding capacitor (C4) connected between the operational amplifier (A1) and a reference voltage source. The capacitors (C1, C2, C3) have one ends connected to the inverting input terminal of the operational amplifier (A1). The other ends of the capacitors (C1, C2) are connected to a power source and the capacitor (C3) is concurrently short-circuited depending upon predetermined timing, and the other ends of the and capacitors (C1, C2) and the output terminal of the operational amplifier (A1) are respectively connected to a non-inverting input terminal of the operational amplifier (A1) after the elapse of a predetermined time from the predetermined timing.

Abstract: A method for compensating an offset voltage temperature drift in a semiconductor strain gage sensor in which a temperature-sensitive power supply is modeled as the one for providing the output voltage V.sub.0 =KV.sub.S (1+.alpha.T), and, under the condition that the resistance of the compensating resistor and the coefficient .alpha. are within practical ranges, respectively, the parameter K is determined so as to minimize the compensating error, thereby both of the primary order term and the secondary order term with respect to the temperature in the offset voltage of the strain gage can be compensated so that the offset temperature drift can be reduced.

Abstract: A semiconductor acceleration sensor, including a semiconductor substrate, in which a mounting portion is formed in the substrate, and first and second cantilevered beams are formed in the substrate in opposite sides of the mounting portion so that these three members are aligned along a straight line, and in which a weight is formed at an end of the first cantilevered beam, and first and second strain sensing devices are formed in approximately the same layout in surface portions of the first and second cantilevered beams, respectively.