Abstract: An analog input voltage signal to be A/D-converted is supplied to a ring gate delay circuit including inverting circuits connected in series in a ring as a supply voltage thereto. The interval for which a pulse circulates the ring varies with the analog input voltage signal. The number of times circulation of the pulse and the position of the pulse for a predetermined interval are detected by a counter to provide upper bits and by a pulse position detector to provide lower bits of A/D conversion result of the analog input voltage signal, respectively. The counter and the pulse position detector are included in a coding process block which is driven by a constant voltage which is different from the analog input voltage signal to the ring gate delay circuit.

Abstract: An analog multiplexer is provided to time divisionally process a reference signal Sa obtained from a reference voltage generating circuit, a temperature signal St obtained from a temperature detecting bridge circuit, and a sensor signal Sd obtained from a pressure detecting bridge circuit. These signals Sa, St and Sd are converted into digital data through a common differential amplification circuit and a common A/D conversion circuit. A correction circuit calculates an applied pressure value based on the digital data produced from the A/D conversion circuit, as a value corrected with reference to the temperature signal St and the reference signal Sa.

Abstract: An intentional offset value is set beforehand. The intentional offset value is larger than a sensing objective signal “sig.” A measuring device is provided for measuring the intentional offset value to obtain a measured intentional offset value “a” representing the quantity of the intentional offset value, and also for measuring a sum of the sensing objective signal “sig” and the intentional offset value to obtain a measured signal value “b” representing a summation of the quantity of the sensing objective signal and the quantity of the intentional offset value. A ratio (b/a) of the measured signal value to the measured intentional offset value is obtained. The obtained ratio is used as noise reducing data for reducing the noise involved in a sensor output.

Abstract: A physical quantity detecting is capable of easily adjusting sensitivity and an offset of a detected output without being increased in size. In a signal processor for driving a sensor element in which fixed electrodes are disposed on both sides of a movable electrode displaced in response to acceleration, a signal generator generates PWM signals PA and PB in which an invalid control period during which the fixed electrodes are both deenergized only during a period corresponding to data M3 stored in a memory, is, at a predetermined ratio, inserted into a valid control period during which the fixed electrodes are alternately energized and their energization ratio is controlled so that the movable electrode is placed in position.

Abstract: A semiconductor sensor including a movable member beam structure having a reduced deflection characteristic. The sensor includes a movable beam structure film suspended from a semiconductor substrate, with a gap interposed between the beam structure film and the substrate. The beam structure film is composed of a plurality of film layers that are laminated in a direction of film thickness. Further, a stress relieving layer is interposed between respective films to reduce overall internal stress on the structure.

Abstract: To provide a time measuring apparatus which is compact and capable of highly accurate measurements, on a semiconductor chip, flip-flops constituting a delayed-signal holding circuit of a first channel and flip-flops constituting a delayed-signal holding circuit of a second channel are disposed alternatingly and in a single row in a circuit region of the delayed-signal holding circuits to latch delayed signals from a pulse-circulating circuit, and flip-flops for latching the same delay signals are mutually adjacent. Due to this, distances between the pulse-circulating circuit and the respective delayed-signal holding circuits become equal, and delay signals having no deviation in delay due to difference in wiring length are supplied to the respective channels, and so uniform measurement can be performed between the respective channels.

Abstract: A physical amount detecting apparatus, preferably, an acceleration sensor, includes a sensor element, an A/D converter, a control unit and an activation unit. The sensor element is activated by a supply voltage and outputs an electric signal in accordance with a predetermined physical amount. The A/D converter digitizes an analog electric signal and outputs digital data. The control unit calculates a control amount in order to control the sensor element, as the electric signal is set to a predetermined output, based on the digital data, and generates a control signal in accordance with the control amount. The activation unit activates the sensor element in accordance with the control signal. As a result, the control unit outputs a detecting signal indicating a physical amount in accordance with the control amount or the control signal.

Abstract: A frequency multiplying device which multiplies the frequency of an externally-supplied reference signal PREF includes a digitally-controlled oscillation circuit, which includes a ring oscillator formed of thirty-two inverting circuits in a ring configuration which are adapted to generate sixteen clock signals having a period that is thirty-two times the inversion time of each inverting circuit and a phase interval that is twice the inverting circuit inversion time, and produces an output signal POUT having a period that corresponds to frequency control data CD at a resolution of the phase difference time of the clock signals, a counter/data-latch circuit which counts the clock signal RCK released by the ring oscillator within one period of the reference signal PREF and delivers the frequency control data CD of the count value to the digital oscillation circuit, and a control circuit which controls the operation of the circuits so that the oscillation output signal POUT having the frequency of the reference s

Abstract: A frequency multiplying device which multiplies the frequency of an externally-supplied reference signal PREF includes a digitally-controlled oscillation circuit, which includes a ring oscillator formed of thirty-two inverting circuits in a ring configuration which are adapted to generate sixteen clock signals having a period that is thirty-two times the inversion time of each inverting circuit and a phase interval that is twice the inverting circuit inversion time, and produces an output signal POUT having a period that corresponds to frequency control data CD at a resolution of the phase difference time of the clock signals, a counter/data-latch circuit which counts the clock signal RCK released by the ring oscillator within one period of the reference signal PREF and delivers the frequency control data CD of the count value to the digital oscillation circuit, and a control circuit which controls the operation of the circuits so that the oscillation output signal POUT having the frequency of the reference s

Abstract: A magnetic detection device including at least one oscillator circuit having a magnetoresistance element which converts a change of magnetism detected into a digital signal and a comparator for comparing the digitalized oscillating frequency of the oscillator circuit with another digitalized oscillating frequency generated from another oscillating circuit by taking a ratio thereof or by detecting a phase difference between the pulse signals. Utilizing the magnetic detection device, the amount of change of magnetism can be stably detected with a high accuracy within a wide range of ambient usage temperatures. The physical quantity detection device includes a magnetic detection device which can detect any physical quantity with a high accuracy.

Abstract: A semiconductor acceleration sensor according to the present invention performs acceleration detection by means of detecting increase or decrease in electrical current flowing between fixed electrodes formed on a semiconductor substrate taking a movable section in a movable state supported on the semiconductor substrate as a gate electrode. Two transistor structures are utilized in this detection. Current between fixed electrodes in one transistor structure increases when the movable section is subjected to acceleration and is displaced. At that time, current between fixed electrodes in the other transistor structure decreases. These two transistor structures are disposed proximately. By means of this proximate disposition, fluctuations in characteristics of both transistors are reduced, and by means of acceleration detection by differential type, temperature characteristics of the two transistors can be canceled favorably.

Abstract: In a physical quantity detecting device for converting a physical quantity into changes in the cycle of a pulse signal and for amplifying the cycle to convert it into digital data, detecting accuracy is improved by increasing the sampling frequency without reducing the degree of the amplification of the cycle of the signal. In a physical quantity detecting device wherein pulse signals having oscillation frequencies changing depending on the ambient strength of magnetism are output from oscillators and wherein the cycles of the pulse signals are amplified by counters and decoder portions and are input to a pulse phase difference encoding circuit to convert the phase difference into digital data, the digital data is interpolated using the pulse signal from one of the oscillators as a sampling signal. This makes it possible to interpolate the digital data to accurately detect the strength of magnetism without providing a special oscillation device for inputting a sampling signal to the interpolation circuit.

Abstract: A method for fabricating a semiconductor sensor wherein deflection of a movable member is disclosed. A silicon oxide film is formed on a silicon substrate, and a movable member composed of polycrystalline silicon is formed on the silicon oxide film by means of a low-pressured chemical vapor deposition process. At this time, silane is caused to flow into an oven, and the supply of silane is stopped when a layer of polycrystalline silicon has been deposited on the silicon substrate, and a first polycrystalline silicon layer is formed. By means of stopping the supply of silane, a silicon oxide layer of a thickness of several angstroms to several tens of angstroms is formed on the first polycrystalline silicon layer by atmosphere O.sub.2. A second polycrystalline silicon layer of a thickness of 1 .mu.m is formed on the silicon oxide layer by means of causing silane to flow into the oven. Patterning by dry etching or the like through a photo-lithographic process is performed to form a movable member.

Abstract: A pulse phase difference encoding circuit provides a digital signal indicating a phase difference between a first input pulse and a second input pulse. The first input pulse is provided to and circulated in a ring signal delay circuit having a plurality of signal delay elements that are connected in series. Intermediate points between the delay elements provide delayed pulses having different delay times. Upon receiving the second input pulse, a selector selects one delay pulse provided by the delay element at which the first input pulse has arrived, and generates a digital positional signal indicating a position of the selected delay element. The number of rounds of circulation of the first input pulse in the ring signal delay circuit is separately counted. According to the number of rounds of circulation of the first pulse and the positional signal, the digital signal indicating the phase difference between the first and second input pulses is formed.

Abstract: In an acceleration sensor having movable gates and a movable electrode and having a signal processing portion, the movable gates generate a differential voltage from acceleration in one direction and its output signal is fed back to the movable electrode. The balance of the movable portion is kept using an electrostatic force which cancels the acceleration acting on the movable portion, and signal detection is stabilized using closed loop control. Since signal detection is on a differential basis, acceleration can be detected in only one direction. Since a change in current is detected as a voltage difference, no carrier wave is required. Since MISFETs having movable gates are formed in pairs, there is no influence of temperature drifts. The use of a differential signal similarly cancels the influence of fluctuations of the power supply. Configuration of an acceleration sensor is thus simplified.

Abstract: A rotational position detecting sensor such as a cylinder discriminating sensor, which is capable of detecting the rotational position of a rotor from immediately after the rotor starts to rotate as at an engine start, arranged such that when used as a cylinder discriminating sensor using a rotor for cylinder discrimination having a tooth formed around a semicircular portion thereof and a groove formed around another semicircular portion thereof, at an engine start, a binary output DO is set forcedly regardless of the positional relation between the rotor and the pick-up means, and then, if a difference Sn=Di-Dr as a result of comparison between the magnetic output Di resulting from rotation of the rotor and a reference value Dr is equal to and larger than 0, the difference most significant bit signal Sn(MSB) is set to "0", or if the difference Sn is less than 0, the Sn(MSB) is set to "1", and if the difference signal Sn is larger than a hysteresis width HYS, the binary output DO is set again, and when the si

Abstract: A pulse phase difference encoding circuit includes a ring delay pulse generating circuit which is formed by a NAND circuit and inverters. Signal lines connecting the NAND circuit and the inverters have uniform load capacity to obtain even time resolutions. The NAND circuit is formed by component transistors one of which is larger in size to have the same delay time as the other inverters. A dedicated latch buffer for applying steeply changing drive pulse to a pulse selector is provided to prevent difference in the measurements. A specific value is outputted in the event of the overflow or underflow of the measurement time to obtain a constant digital output.

Abstract: A ring oscillator for circulating pulse edges of two types therein includes an even number of inverting circuits connected in a ring. Each of the inverting circuits is operative to invert an input signal and output an inversion of the input signal. One of the inverting circuits is a first start inverting circuit which starts an operation of inverting an input signal in response to a first control signal applied from an external input. One of the inverting circuits except the first start inverting circuit and an inverting circuit immediately following the first start inverting circuit is a second start inverting circuit which starts an operation of inverting an input signal in response to a second control signal.

Abstract: In a digital control pulse generator including a ring oscillator composed of multiple inversion circuits connected in a ring for circulating a pulse, a counter and selectors which turn data of a flip-flop to high when a counted value of the pulse from a terminal of the ring oscillator becomes a value corresponding to ten high order bits of control data, a pulse selector for taking out a clock of the flip-flop from the inversion circuit at the position specified by four bit control data and a delay line and logical product circuit which turn an output signal of the system to a high level for a predetermined time when the output of the flip-flop turns high, a register and adder accumulate the four low order bits of the control data every time the output signal turns high to update the data four bit data. As a result, the ring oscillator may be continuously operated and an oscillation cycle proportional to the control data may be set.

Abstract: An object of the present invention is to provide an A/D conversion device capable of compensating for quantizing errors occurring as a result of variations in operating conditions and a physical quantity detection device using this A/D conversion device.