摘要:
A semiconductor pressure sensor utilizing electrostatic capacitance has a plurality of pressure sensing electrostatic capacitances and a reference electrostatic capacitance formed on one side of a silicon chip. As a movable electrode, the pressure sensing electrostatic capacitances each have a diaphragm, which may have a displacement portion composed of a central area thereof, and a peripheral portion which is more deformable than the central portion.
摘要:
In a capacitance type pressure sensor, a diaphragm is formed of a fragile material using an impurity-diffused monocrystal silicon and constitutes a stable pressure-responsive structure which does not undergo a plastic deformation. Between the diaphragm and a movable electrode is formed an oxide film to diminish stray capacitance between the movable electrode and a substrate and also between the movable electrode and a impurity-diffused layer. The oxide film and the movable electrode are each divided into plural regions so that the divided regions of the movable electrode are formed on the divided regions of the oxide film, thereby diminishing stress strain induced by a difference in therm expansion coefficient among the diaphragm, oxide film and movable electrode. The upper surface of a fixed electrode is covered with a structure for the fixed electrode which structure is formed by an insulating polycrystal silicon film not doped with impurity whereby the rigidity of the electrode is enhanced and it is possible to diminish a leak current.
摘要:
A sensor adjusting circuit for adjusting a digital sensor, whose circuit scale is small and which can maintain high accuracy in a wide adjustment range is provided. A sensor adjusting circuit for adjusting an analog input signal inputted from a sensor and outputting it as another analog output signal in accordance with a physical quantity to be sensed, comprises: a first analog-to-digital converter having an analog integrator (2) for integrating the analog input signal, a comparator (3) for comparing an output of the analog integrator with a predetermined value, and a D/A converter (7) for outputting an output of the comparator as the input signal; and a second digital-to-analog converter (5) for converting the output of the comparator and outputting it as the analog output signal.
摘要:
A sensor adjusting circuit for adjusting a digital sensor, whose circuit scale is small and which can maintain high accuracy in a wide adjustment range is provided. A sensor adjusting circuit for adjusting an analog input signal inputted from a sensor and outputting it as another analog output signal in accordance with a physical quantity to be sensed, comprises: a first analog-to-digital converter having an analog integrator (2) for integrating the analog input signal, a comparator (3) for comparing an output of the analog integrator with a predetermined value, and a D/A converter (7) for outputting an output of the comparator as the input signal; and a second digital-to-analog converter (5) for converting the output of the comparator and outputting it as the analog output signal.
摘要:
A sensor adjusting circuit for adjusting a digital sensor, whose circuit scale is small and which can maintain high accuracy in a wide adjustment range is provided. A sensor adjusting circuit for adjusting an analog input signal inputted from a sensor and outputting it as another analog output signal in accordance with a physical quantity to be sensed, comprises: a first analog-to-digital converter having an analog integrator (2) for integrating the analog input signal, a comparator (3) for comparing an output of the analog integrator with a predetermined value, and a D/A converter (7) for outputting an output of the comparator as the input signal; and a second digital-to-analog converter (5) for converting the output of the comparator and outputting it as the analog output signal.
摘要:
By sealing a diaphragm with less processes and lower cost and reducing deformation due to remaining stress, a stable and highly reliable pressure sensor construction is proposed. The pressure sensor is low in measurement error and small in floating capacitance and leakage current and good in characteristic. As a means to attain the above object, a polycrystalline silicon diaphragm is sealed with a silicon oxide film deposited through a LPCVD method and then completely covered. The diaphragm is placed on a surface of a semiconductor substrate with a nearly constant gap of 0.15 to 1.3 μm, and has difference-in-grade constructions of a deformation reducing means due to remaining stress.
摘要:
Dynamic quantitative displacement is converted stably and straight into voltage (D.C. output) by using a high speed detection driving frequency without restricting a response of an operational amplifier. When a dynamic quantity detection electrostatic capacitance changes according to a dynamic quantity, electric charges stored in this element and in a reference electrostatic capacitance become unbalanced to produce a difference value, and an output of an operational amplifier changes according to the difference in electric charge quantity. However, the output becomes finally stable when the electric charges in the dynamic quantity detection electrostatic capacitance and in the reference electrostatic capacitance become equal. The output is proportional to a reciprocal of the dynamic quantity detection electrostatic capacitance and it is a D.C. voltage. Further, output without depending on integration feedback capacitance (feedback condenser) CF can be obtained.
摘要:
An accelerometer having a movable electrode which is moved according to acceleration with respect to a fixed electrode disposed in opposition to the movable electrode. An output device generates an output voltage which is proportional to the acceleration by measuring a gap between the movable electrode and the fixed electrode. A pulse width modulator generates pulses, wherein a pulse width of the pulses is modulated according to the output voltage, and a feedback device feeds back an electrostatic force which is proportional to the pulse width of the pulses from the pulse modulator between the movable electrode and the fixed electrode. As the acceleration in the acceleration sensor is linearly detected, the acceleration sensor is easily adjusted.
摘要:
In a semiconductor memory device, the drain of a transistor for pre-charging is connected to a data line via the Y switch. Lower level bit signals are input into an X decoder for selecting the word line in a memory cell array; and higher level bit signals are input into a Y decoder for selecting the Y switch control signal lines. The addresses in the memory cell array are arranged sequentially in the direction of the data lines.
摘要:
A circuit for protecting a load from an overvoltage can be integrated together with the load on the same chip by an MOS transistor manufacture process. This overvoltage protecting circuit is composed of a surge protection circuit, an overvoltage detecting circuit and a switching circuit. The surge protection circuit including two MOS transistors operates so that a surge voltage applied to a power supply receiving terminal is clamped by virtue of the source-drain breakdown voltage of the two MOS transistors, thereby absorbing the surge energy. The overvoltage detecting circuit including two MOS transistors operates so that a DC voltage supplied from the surge protection circuit is monitored with the source-drain voltage of the two MOS transistors taken as a reference voltage, thereby detecting an overvoltage. An overvoltage detection output brings an MOS transistor of the switching circuit into a turned-off condition to protect the load.