Abstract: This application relates to methods and apparatus for operating MEMS sensors, in particular MEMS capacitive sensors (CMEMS) such as a microphones. An amplifier apparatus is arranged to amplify an input signal (VINP) received at a sense node from the MEMS capacitive sensor. An antiphase signal generator generates a second signal (VINN) which is in antiphase with the input signal (VINP) and an amplifier arrangement is configured to receive the input signal (VINP) at a first input and the second signal (VINN) at a second input and to output corresponding amplified first and second output signals. This converts a single ended input signal effectively into a differential input signal.

Abstract: A sensing system with an AC feedback to the non-signal and non-biased terminal of the transducer. An impedance element, such as two anti-parallel diodes, are provided at the amplifier input, and the amplifier gain is negative and has a size sufficient to ensure that the input on the one terminal does not exceed the forward voltage of the diode.

Abstract: This application relates to methods and apparatus for operating MEMS sensors, in particular MEMS capacitive sensors (CMEMS) such as a microphones. An amplifier apparatus (300) is arranged to amplify an input signal (VINP) received at a sense node (104) from the MEMS capacitive sensor. An antiphase signal generator (201; 304) generates a second signal (VINN) which is in antiphase with the input signal (VINP) and an amplifier arrangement (105; 305) is configured to receive the input signal (VINP) at a first input and the second signal (VINN) at a second input and to output corresponding amplified first and second output signals. This converts a single ended input signal effectively into a differential input signal.

Abstract: Cables (1, 2) comprise first and second conductors (1, 2) for transporting signals to be picked-up in contactless manners. At first/second locations (3, 4), the first and second conductors (1, 2) are at first/second distances from each other. The first locations (3) are neutral locations where the conductors (1, 2) are parallel. The second locations (4) are pick-up locations. The second distances are larger than the first distances. Pick-up devices for picking-up signals in a contactless manner from the cables (1, 2) comprise parts for defining minimum values of the second distances. These parts may comprise core-parts, such as center ends (10) of E-shaped magnetic cores further comprising outer ends (11, 12) and backs (13). Methods for installing pick-up devices comprise steps of at second locations (4) increasing a distance between the first and second conductors (1, 2) from a value of the first distance to a value of the second distance.

Abstract: The invention relates to a coupling device (4) for four phases of a multi-phase converter (2). Said coupling device (4) includes four coupling modules (6, 8, 12, 14), each of which encompasses four parallel through-holes. At least one section of a conductor loop (18, 20, 22, 24) for a phase. At least one section of a conductor loop (18, 20, 22, 24) for a phase penetrates a through-hole of a coupling module (6, 8, 12, 14), sections of conductor loops (18, 20, 22, 24) for at least two phases penetrating all four through-holes of a coupling module (6, 8, 12, 14).

Abstract: A high-voltage driver amplifier for piezo haptics comprises an input amplifier having a gain greater than one, a first amplifier of an amplifier pair coupled to an output of the input amplifier, a second amplifier of the amplifier pair coupled to the output of the input amplifier, a first impedance coupled between an output of the first amplifier of the amplifier pair and an input of the input amplifier, and a second impedance coupled between the output of the first amplifier of the amplifier pair coupled to an output of the second amplifier of the amplifier pair. A substantially capacitive load is coupled to the output of the second amplifier. The substantially capacitive load is a piezo-capacitance, wherein the piezo-capacitance is employed in haptics. The second impedance, a shunt impedance, allows for a feedback of output variations between the first amplifier and the second amplifier over the first impedance.

Abstract: A circuit for a charge amplifier for converting piezoelectric measurement signals continuously sets the output signal of the amplifier to a value close to zero, such that a reset switch becomes unnecessary. The amplifier includes a pulse generator that provides the output signal of the amplifier in the form of pulses, which are easy to transmit with low interference. The pulse frequency is proportional to the rate of change of charge. The pulses, which are added in a counter, represent a value proportional to the change in the charge since the last counter reset, which is proportional to the present measured value at the measurement element.

Abstract: A signal level conversion circuit 1 includes a first differential amplifier circuit 10 and a second differential amplifier circuit 20. The first differential amplifier circuit 10 multiplies a potential difference between a first input signal and a second input signal by G1 thereby providing an output signal. The second differential amplifier circuit 20 multiplies a potential difference between the output signal of the first differential amplifier circuit 10 and the second input signal by G2 thereby providing an output, where the two gains satisfy the relation of G1×G2<0 and 0<?(G1+1)×G2<2.

Abstract: An output circuit of a charge mode sensor includes a second resistor and an operational amplifier. The second resistor connects an output portion of the charge mode sensor and a ground. The operational amplifier is configured to output a detection signal that varies in accordance with an amount of charge kept in the charge mode sensor. The operational amplifier includes an inverting input portion, a non-inverting input portion, and an output portion. The inverting input portion is connected to the output portion of the charge mode sensor via a sensor cable. The non-inverting input portion is connected to a reference voltage. The output portion is connected to the inverting input portion via a first resistor.

Abstract: Methods and devices for increasing a sensor resolution are disclosed. In one example, a two measurement process is used. A first measurement is used to effectively measure across a full range (e.g. 0 to 5 VDC) of the sensor. This first measurement may identify the current operating point of the sensor (e.g. 3.5 VDC). A second measurement may then be made to effectively measure across a sub-range of the sensor that encompasses the current operating point of the sensor (e.g. across a sub-range of 3.0 to 4.0 VDC for a current operating point of 3.5 VDC). The gain of the amplifier may be raised during the second measurement to produce a higher resolution measurement. In some cases, the first measurement may be used to determine an appropriate offset that may be applied so as to scale the amplifier to the desired sub-range of sensor that includes the current operating point of the sensor. In some cases, the two measurements may be used together to compute an effectively higher resolution measurement signal.

Abstract: A capacitive sensor amplifier circuit comprising: a capacitive sensor; a bias voltage supply connected across the capacitive sensor via a bias resistor; an operational amplifier having an input connected to the capacitive sensor; and a feedback capacitor connected between the input and an output of the amplifier, the input and output being of the same sign.

Abstract: A circuit arrangement for providing an analog signal is disclosed. The circuit arrangement comprises a biasing resistor; an analog input arrangement; and a signal output, wherein the biasing resistor and the analog input arrangement are connected in series between a supply voltage and a reference voltage, and the signal output is connected such that the alternating voltage over the biasing resistor is provided as an output signal. An electronic apparatus comprising such a circuit arrangement is also disclosed.

Abstract: A controller, either a microprocessor or finite state machine, is used to generate a pulse train whose frequency and duty cycle can be varied to alter the frequency and amplitude of the output of a driven audio transducer. The ability to control both frequency and amplitude allows programmatic synthesis of many audio effects such as steady tones, warbles, beeps, sirens and chimes with no hardware or circuit changes. The transducer can be a piezoelectric bender or a speaker. The output of the controller controls a switch that builds current in an inductor when the switch is on. When the switch is turned off, the energy stored in the inductor is dumped into the audio transducer, either directly or through intermediate capacitor storage. This allows the generation of voltages across the transducer many times the supply voltage.

Abstract: A variable circuit that has a device that changes the mechanical state thereof and has a characteristic that is changed by a change of the mechanical state of the device, the variable circuit including: a controlling section 20 that turns the device from a current state, which is a current mechanical state, to a different state, which is a state different from the current state, and returns the device from the different state to the current state; and a trigger transmitting section 22 that transmits a first trigger to turn said device from the current state to the different state to the controlling section 20.

Abstract: An apparatus for reducing offset voltage drifts in a charge amplifier circuit is disclosed. The apparatus includes a charge amplifier circuit and a bias current compensation circuit. The bias current compensation circuit supplies bias current to lower any offset voltage drift at the output of the charge amplifier.

Abstract: An apparatus for reducing offset voltage drifts in a charge amplifier circuit is disclosed. The apparatus includes a charge amplifier circuit and a bias current compensation circuit. The bias current compensation circuit supplies bias current to lower any offset voltage drift at the output of the charge amplifier.

Abstract: A positive charge of a sensor element is charged in a signal converting circuit, is converted into a positive voltage, and is outputted. When the polarity of the charge of the sensor element is inverted to the negative and an output of the signal converting circuit is decreased, the leaked charges are superimposed and become the negative. An automatic correction circuit detects the negative output and discharges the charges so as to set the input to “0”. Thus, the offset of the signal level due to the charge leakage is automatically corrected.

Abstract: An object of the present invention is to provide a charge amplifier which can be operated at low cost so that electric charge generated in a piezoelectric pressure sensor having one end grounded is converted into a voltage signal. In the charge amplifier (1) according to an embodiment of the present invention, a plus side power source input terminal of an operational amplifier (5) is connected to a plus power source (+5 V) while a minus side power source input terminal of the operational amplifier (5) is grounded, so that the operational amplifier (5) is supplied with a single power source. Further, an offset voltage lower than the plus power source voltage but higher than the ground potential is applied to a non-inverted input terminal of the operational amplifier (5). Accordingly, change of pressure in both positive and negative directions can be converted into a voltage signal with the offset voltage as its center though the operational amplifier (5) is driven by a single power source.

Abstract: In order that an amplifier with a gain proportional to source voltage is obtained, the drain-source voltages of first and second P-channel MOS-FETs are zero-biased, and a voltage shifted higher by the amount of the threshold voltage of the P-channel MOS-FET on the basis of a voltage obtained by dividing the power source voltage by resistors is applied to the positive input terminal of an operational amplifier. The gate of one of the first and second MOS-FETs is connected to a circuit ground, and a negative fixed voltage with reference to the potential obtained by dividing the power source voltage by resistors is applied to the gate of the other MOS-FET. The ON resistances of the two MOS-FETs are used as the input resistor and the feedback resistor of the operational amplifier, respectively.

Abstract: In general terms, the present invention is an amplifier based on a diode device in which the separation of the electrodes controls the magnitude of the current flowing through the diode. The amplifier of the present invention comprises an emitter electrode separated from a collector electrode by a distance; one or more positioning elements in contact with either or both electrodes to control the magnitude of the distance; a heater element in thermal contact with the emitter electrode; a controller element having an electrical input to be amplified in electrical contact with the positioning elements so as to control the magnitude of the distance; and an amplified output between the collector and the emitter.

Abstract: An amplifier housing assembly is disclosed. The housing assembly includes a first section including a first plurality of holes; and a second section including a second plurality of holes. The first and second sections are interconnected. The first and second sections have a common back wall and a common bottom plate. The first plurality of holes and the second plurality of holes are at two different parallel planes.

Abstract: An object of the present invention is to provide a charge amplifier which can be operated at low cost so that electric charge generated in a piezoelectric pressure sensor having one end grounded is converted into a voltage signal.

Abstract: Differential charge amplifier for processing charge signals from a rotation rate sensor, with a test signal being applied to the differential charge amplifier so that during normal operation the output of the amplifier corresponds to the test signal as well as to the charge signals.

Abstract: An amplification circuit for electric charge type sensor has a simple circuit configuration in which a common mode noise is adequately cancelled. In the acceleration sensor amplification circuit, the inversion input terminal of an operational amplifier is connected to one end of the acceleration sensor (G sensor). In addition, a feedback circuit including a feedback resistor and a feedback capacitor connected in parallel to each other is connected between the inversion input terminal and the output terminal of the operational amplifier. Furthermore, a cancellation circuit including a cancel resistor and a cancel capacitor connected in parallel to each other is connected between the non-inversion input terminal of the operational amplifier and a reference voltage.

Abstract: A system and method of processing received signals in an ultrasound imaging system is disclosed. In the system, the received signals are amplified by means of a gain controlled amplifier, and the gain of the amplifier is varied, by varying the load capacitance, as a function of depth (time) to compensate for the attenuation of ultrasonic energy at different depths within a patient's body.

Abstract: A voltage supply unit which operates at an internal switching frequency and has a capacitor connected in parallel with its output is connected to the input of a sensor unit operating at an internal switching frequency. The connecting line contains a resistor which, together with a capacitor connected in parallel with the input, forms a filter.

Abstract: An amplification circuit for electric charge type sensor has a simple circuit configuration in which a common mode noise is adequately cancelled. In the acceleration sensor amplification circuit, the inversion input terminal of an operational amplifier is connected to one end of the acceleration sensor (G sensor). In addition, a feedback circuit including a feedback resistor and a feedback capacitor connected in parallel to each other is connected between the inversion input terminal and the output terminal of the operational amplifier. Furthermore, a cancellation circuit including a cancel resistor and a cancel capacitor connected in parallel to each other is connected between the non-inversion input terminal of the operational amplifier and a reference voltage.

Abstract: An amplification circuit for electric charge type sensor has a simple circuit configuration in which a common mode noise is adequately cancelled. In the acceleration sensor amplification circuit, the inversion input terminal of an operational amplifier is connected to one end of the acceleration sensor (G sensor). In addition, a feedback circuit including a feedback resistor and a feedback capacitor connected in parallel to each other is connected between the inversion input terminal and the output terminal of the operational amplifier. Furthermore, a cancellation circuit including a cancel resistor and a cancel capacitor connected in parallel to each other is connected between the non-inversion input terminal of the operational amplifier and a reference voltage.

Abstract: An amplification circuit for electric charge type sensor has a simple circuit configuration in which a common mode noise is adequately cancelled. In the acceleration sensor amplification circuit, the inversion input terminal of an operational amplifier is connected to one end of the acceleration sensor (G sensor). In addition, a feedback circuit including a feedback resistor and a feedback capacitor connected in parallel to each other is connected between the inversion input terminal and the output terminal of the operational amplifier. Furthermore, a cancellation circuit including a cancel resistor and a cancel capacitor connected in parallel to each other is connected between the non-inversion input terminal of the operational amplifier and a reference voltage.

Abstract: An amplifier having an operational amplifier, and in which an output terminal of an acceleration sensor is connected to the non-inverting input terminal of the operational amplifier, a leakage resistor R1 is connected between a non-inverting input terminal and the reference voltage, a first capacitor C1 and a first resistor R2 are connected in series with each other between the inverting input terminal and the reference voltage, first and second voltage dividing resistors are connected in series with each other between the output terminal of the operational amplifier and the reference voltage, and a second resistor R3 and a second capacitor C2 are connected in parallel with each other between the connection point of the voltage dividing resistors and the inverting input terminal, and the relationship C1×R2<C2×R3 is satisfied.

Abstract: A circuitry for measuring piezoelectric signals for a piezotransducer/charge amplifier combination with a range capacitor including a voltage divider with a switch element providing a feedback signal to the measuring input of a charge amplifier. The switching element is controlled by a pulse generator for zeroing. The range capacitors charge to a certain class and voltage at the commencement of the measuring. An adjustment of the range of the range capacitor is provided by a second voltage divider.

Abstract: An electronic circuit serving as an interface between a piezoelectric transducer and a circuit for processing a measuring signal provided by said transducer, said electronic interface circuit serving for providing a constant direct current to said piezoelectric transducer, and for pre-processing an electric signal provided by the transducer via a voltage modulator, said electronic interface circuit being connected to said voltage modulator by a cable having two terminals at each end, the two terminals at a first end of the cable being connected to the output of the voltage modulator and the two terminals at a second end of the cable being connected to said electronic interface circuit.

Abstract: A method (100) of providing a time delay to a signal utilizing a surface acoustic wave ladder filter includes a first step (102) of providing a piezoelectric substrate. A second step (104) includes disposing series and shunt coupled surface acoustic wave transducers in a ladder configuration on the substrate with each of the transducers having an associated aperture and an associated number of interdigital electrode elements. A third step (106) includes configuring the associated aperture and an associated number of interdigital electrode elements for each surface acoustic wave transducer for maximum phase linearity of the ladder filter and uniform group delay response from the ladder filter. A fourth step (108) includes adjusting the number of transducers in the ladder filter to provide a desired average group delay. Subsequently passing a signal through the ladder filter will delay the signal by a time equal to the group delay.

Abstract: In an intermediate frequency amplifier circuit having a crystal filter and a transistor amplifier, a tuning circuit including a coil and a capacitor is provided therebetween, and a current feedback resistor and a voltage feedback resistor are connected to the amplifying transistor. The resistance component of impedance is matched between the crystal filter and the amplifier by suitably selecting values of the resistors. Further, the reactance component of the impedance is matched therebetween by suitably selecting values of the coil and the capacitor. Thus, it is possible to obtain impedance matching between the crystal filter and the amplifier without degradation of NF and hence S/N ratio due the thermal noise caused by resistance elements in a conventional resistive attenuator which is conventionally used for impedance matching.

Abstract: The present invention concerns a high impedance signal source driving a relatively low input impedance mechanical resonating device such as a ceramic filter having an input impedance which varies with frequency. The high impedance source is further loaded by a resonant circuit tuned to the center frequency of the mechanical resonating device. The skirts of the resonant tuned circuit decrease in impedance on both sides of the center frequency of interest substantially compensating for the change of circuit gain with frequency due to the change of input impedance with frequency of the ceramic filter.

Abstract: Comb filter having a comb like band pass characteristic curve by using an ultrasonic delay line (9) is improved to reduce its size. An input signal is given through an impedance element 13 to a single terminal 10a of an improved delay line 9, wherein the single terminal serves as the input terminal and at the same time as the output terminal. Signals at both ends of the impedance element 13 are given to a mixing circuit 15 for summing or subtracting thereby. In the improved delay line 9, the ultrasonic wave radiated from the input terminal travels twice the conventional delay line and comes back to the original terminal, and thereby a sufficient propagation distance is obtainable in a small delay line.

Abstract: In differential amplifier circuits of the type having first and second transistors, the emitter of each transistor is connected to a different current source and the emitters are coupled by a ceramic filter tuned to 455 KHz. In one embodiment, wherein the transistors have symmetrical resistive loads, an inductor is connected across the filter to tune out capacitance across the terminals of the filter. In another embodiment, the circuit includes an unbalanced and complex load. In yet another embodiment, the circuit has active load circuitry and an inductor is connected across the filter to tune out capacitance across the terminal of the filter.

Abstract: A band-pass filter and gain stage which produces a desired passband at a preselected center frequency. The present invention can be characterized as being a very passive frequency door whose output is lightly coupled to a broad band frequency amplifier having a high gain. The present invention includes an input connected to an input impedance stage, which is connected to a monolithic filter stage, which is connected to a second impedance stage, which is connected to a gain stage, which, in turn, is connected to an output terminal. A piezoelectric quartz crystal monolithic filter or a piezoelectric ceramic monolithic filter can be employed depending on the width desired for the passband response.

Abstract: A surface acoustic wave filter arrangement is provided in which both filter and associated driving amplifier are arranged in the same integrated circuit package.

Abstract: A circuit for at least two frequencies comprises a high frequency filter and a low frequency filter and a pair of series connected terminating resistors, the high frequency filter being connected to a first terminating resistor and directly to a common circuit point, the low fequency filter being connected to the connection between the two resistors and the order of magnitude of the terminating resistors being the same as the order of magnitude of the required terminating resistance of the filters.

Abstract: A filter circuit includes an acoustic surface-wave filter device having an input transducer comprised of a set of interleaved electrodes disposed on a first portion of a body of piezo-electric material adapted to propagate acoustic surface waves for producing an acoustic surface-wave signal in response to an input signal applied to the input transducer, and an output transducer comprised of a set of similar interleaved electrodes disposed on a second portion of the piezo-electric body spaced a selected distance from the first portion for receiving the acoustic surface-wave signals so as to produce a corresponding output signal having a selected frequency response. The frequency response (e.g., bandwidth) of the acoustic surface-wave filter device is controlled by selectively changing the number of conductor elements constituting the interleaved electrodes of the input and output transducers.

Abstract: A band-pass filter comprising a plurality of coupled electromechanical filters is disclosed. Each electromechanical filter has a frequency pass-band centered about a fundamental frequency and a plurality of higher frequency pass-bands which are centered about overtones of the fundamental frequency. At least one of the electromechanical filters has a fundamental frequency that is different from the other filters and all the filters have a common overtone frequency. The band-pass filter will pass all frequencies falling within the band about the common overtone frequency, while all other frequencies will be suppressed.