Abstract: A microphone unit capable of suppressing the sensitivity reduction due to a parasitic capacitance that occurs depending on the structure of an electret capacitor, can be realized by the following manner. Specifically, an output signal (Vout) that is the inverted output of an input signal (Vin) is inputted to an operational amplifier (OP2) that is an inverting amplifier, such that the output signal (Vout) has the same phase as the input signal (Vin) and is amplified. With an output signal (Vfb) of the operational amplifier (OP2) connected to a first electrode of a parasitic capacitor (CX), the parasitic capacitor (CX) functions as a coupling capacitor, while a feedback is applied to an electret capacitor (EC). This allows for an increase in the voltage between both terminals of the electret capacitor (EC), and thus suppresses that the sensitivity of the microphone unit is lowered due to the parasitic capacitor.

Abstract: A semiconductor electret capacitor microphone includes a vibration membrane, a semiconductor chip on which are formed a necessary electronic circuit, a fixed electrode, a spacer for preserving a predetermined space between the fixed electrode and the vibration membrane, and a case for enclosing the semiconductor chip and the vibration membrane in such a configuration that the fixed electrode is connected to the ground and the vibration membrane is connected to an input electrode of the semiconductor chip.

Abstract: The voltage corresponding to the pressure outputted from a Wheatstone bridge having resistors R1 to R4 is amplified by a differential amplifier 3 and operational amplifiers OP1, OP2, and then outputted through an output terminal 4 to an external device as the output voltage VOUT. The offset voltage ZSOUT is outputted from the operational amplifier OP10. The output voltage VOUT and the offset voltage ZSOUT are fed back to the reference source voltage Vsen by operational amplifiers OP3 to OP5. In consequence, a non-linear output property of output-attenuating or output-increasing type can be easily obtained, while errors due to the offset voltage ZSOUT can be diminished.

Abstract: The voltage corresponding to the pressure outputted from a Wheatstone bridge having resistors R1 to R4 is amplified by a differential amplifier 3 and operational amplifiers OP1, OP2, and then outputted through an output terminal 4 to an external device as the output voltage VOUT. The offset voltage ZSOUT is outputted from the operational amplifier OP10. The output voltage VOUT and the offset voltage ZSOUT are fed back to the reference source voltage Vsen by operational amplifiers OP3 to OP5. In consequence, a non-linear output property of output-attenuating or output-increasing type can be easily obtained, while errors due to the offset voltage ZSOUT can be diminished.

Abstract: A large-time-constant microphone filter which contains resistance and capacitance as its constituent and can be formed in the same semiconductor chip as a microphone unit is achieved, which results in downsizing and cost reduction of the microphone unit. A transistor of a current mirror circuit is used as a resistance of a microphone filter, utilizing a differential resistance produced by a channel length modulation effect of the transistor or an Early effect. When variations in the drain-source voltage of the transistor occur, the drain-source current of the transistor slightly varies in linear characteristics and the transistor serves a high value of resistance. Being a current mirror circuit, the microphone filter is resistant to characteristic variations due to temperature changes and can be formed in a semiconductor chip without a significant increase in chip area.

Abstract: A semiconductor electret capacitor microphone including a vibration membrane 200, a semiconductor chip 100 on which are formed a necessary electronic circuit 130, a fixed electrode 110, and a spacer 120 for preserving a predetermined space between the fixed electrode 110 and the vibration membrane 200, and a case for enclosing the semiconductor chip 100 and the vibration membrane 200, in such a configuration that the fixed electrode 110 is connected to the ground and the vibration membrane 200 is connected to an input electrode 143 of the semiconductor chip 100.

Abstract: A semiconductor integrated circuit has an amplifier circuit for amplifying a voltage change accompanying a change in a capacitance of a capacitor in an electric microphone. The integrated circuit includes a voltage conversion circuit for voltage converting this voltage change; an amplifier for amplifying a voltage converted by the voltage conversion circuit; and a reference bias circuit for producing and outputting a reference bias voltage to the amplifier. The voltage conversion circuit operates so that the midpoint of the voltage change is a value approximately ½ the dc voltage supplied to the amplifier.

Abstract: The object of the present invention is to obtain high-precision semiconductor pressure detecting devices without unevenness in gauge resistance values. When a recrystal silicone film 23 is formed by use of laser, a crystal subgrain boundary 27 generates, and crystal fault is included in (100) direction. A metallic wiring 51 of aluminum or gold is arranged on said crystal subgrain boundary 27 crossing a gauge resistance 3A. The current running through a gauge resistance formed by said recrystal silicone film 23 runs into said metallic wiring 51 at the portion of said crystal subgrain boundary 27. Therefore, the current running through said gauge resistance is unlikely to be affected by crystal fault. High-precision and high-sensitivity semiconductor pressure detecting devices are realized with reduced affection by crystal fault.

Abstract: A semiconductor pressure detecting device comprises a package having a pressure introducing hole; a base plate which has a first through hole and is mounted in the package; a base mounted on the base plate; and a semiconductor pressure sensor chip which is mounted on the base; wherein the base plate has a thickened portion formed around the first through hole and is fixed by welding the circumference of the thickened portion onto the package.

Abstract: A semiconductor pressure sensor includes a substrate with a semiconductor pressure detecting element mounted thereon. The pressure detecting element includes a pressure detector, having two terminals, which generates a small potential difference between the two terminals in proportion to a pressure applied to the pressure sensor, and a peripheral circuit for differential amplification of the small potential difference based on a reference voltage applied thereto. Reference voltage setting resistors are used to set the reference voltage to a predetermined value. Also, temperature compensating resistors compensate for an error produced in the pressure detector as a result of change in temperature and an error caused in the peripheral by a change of the reference voltage resulting from the change in temperature, respectively.

Abstract: A four quadrant multiplying circuit includes a first compression circuit having a PMOS differential input structure for reducing and outputting a first input voltage and a reference voltage by a predetermined ratio; a second compression circuit having an NMOS differential input structure for reducing and outputting a second input voltage and a reference voltage by a predetermined ratio; a current converting circuit for converting a constant current input from a constant-current circuit to a first and a second constant current on the basis of the second input voltage and reference voltage reduced by a predetermined ratio and output by the second compression circuit; first and second voltage converting circuits. The first and second constant currents output by the current converting circuit are received by the device sources, and the outputs of the first and second voltage compression circuits are received by the device gates.

Abstract: A semiconductor pressure detecting device comprises a package having a pressure introducing hole, a base plate which has a first through hole at the center thereof and is bonded on the periphery thereof to the inside of the package so that the first through hole becomes concentric with the pressure introduction hole, a mount which has a second through hole at the center thereof and is mounted on the base plate so that the second through hole becomes concentric with the first through hole and located inside the bonding portion of the package and the base plate, and a semiconductor pressure sensor chip, wherein the base plate has a groove which surrounds the mount at a position inside of the bonding portion.

Abstract: Provided is a semiconductor acceleration detecting device capable of improving the impact resistance in handling the device singly with a relatively simple construction without providing any other member. The device is a semiconductor acceleration detecting device S1 having a construction in which a package body Pc formed by mounting an acceleration detecting semiconductor chip on a die pad and molding it with the lead terminal sections Tr of lead pins protruding outward is combined by bonding with a main body section Bd, so that the device is totally formed into an approximately rectangular parallelepiped shape comprised of a pair of first surfaces F1 from which the lead terminal sections are protruding, a pair of second surfaces F2 approximately perpendicular to a suspension lead, and a pair of third surfaces F3 approximately parallel to the die pad.

Abstract: A pressure detection apparatus including a pressure detection diaphragm, pressure detection circuit for outputting a pressure detection signal proportional to a pressure applied to the pressure detection diaphragm and clamping circuit for clamping the pressure detection signal to a predefined maximum or minimum value when the detected pressure signal is larger than the maximum value or less than the minimum value. Signal clamping by the clamping circuit is cut-off or cancelled when the pressure applied to the pressure detection diaphragm causes an operational error. This operational error may be detected by forming part of the clamping circuit on a semiconductor diaphragm of the sensor. Also, a failure detection circuit may be used to detect sensor failure and then cancel signal clamping.

Abstract: A semiconductor pressure sensor of the invention comprises a silicon plate having a crystalline plane of (100) or (110), and the silicon plate comprises a diaphragm having the crystalline plane of (100) or (110), and a base surrounding said diaphragm. Further, a plurality of piezoresistor elements formed on the diaphragm. An area S (m.sup.2) and a thickness t (m) of said diaphragm satisfies a following relation:S/t.sup.2 <(.epsilon./(P.sup.3/2 K)).sup.1/3,where P (kPa) denotes applied pressure and .epsilon. (%) denotes a desired error of linearity of pressure, andK=1*10.sup.-4 (kPa).sup.