Showing papers on "Electronic filter published in 1992"

Surface-acoustic-wave filter

Abstract: A SAW filter comprising a piezoelectric substrate and at least two filter tracks formed on the substrate, each having at least two IDT electrodes for input and output. The two filter tracks have substantially the same phase within a pass band, while it is substantially inverse-phased outside the pass band. For realizing the above-described conditions, input IDT electrode of one filter track is connected in parallel with input IDT electrode of the other filter track, while output IDT electrode of one filter track is connected in parallel with output IDT electrode of the other filter track. Furthermore, frequency values of said two filter tracks substantially coincide at a point 3dB lower from the peak transfer function value. Thus the above-configured SAW filter of the present invention is smaller in the overall size and offers a broad pass band and a steep attenuation characteristic.

Modeling of thin film resonators and filters

Abstract: Thin-film piezoelectric resonators have been used in the synthesis of crystal filters at microwave frequencies and for oscillator control. These resonators may be modeled using equivalent circuits or analytical expressions derived from acoustic boundary value excitation problems. Results of the modeling are described in three forms: (1) impedance characteristics plotted versus frequency, (2) analytical expressions of impedance, and (3) lumped-element equivalent circuits useful for filter design and analysis. Two filter types are modeled: a simple ladder filter and a more complex stacked crystal filter using acoustically coupled resonators. >

Transverse electrical filter operating optically

Abstract: The invention relates to a programmable transverse filter required for the matched filtering of signals with very wide passband. The signals to be filtered modulate one or more optical carriers (F1) in a modulator (MOD). Each carrier is distributed over several channels by a distributor (DIV). A delay creation circuit (CR1 to CRn) is provided in each channel. These channels are next summed after having been correctly delayed and assigned a coefficient characteristic of the signal to be detected.

Regenerative braking protection for an electrically-propelled traction vehicle

Abstract: An electric propulsion system for a traction vehicle includes a controllable power converter operable in either a propulsion or an electric braking mode in which power is withdrawn from a wayside source or returned to the source, respectively. The wayside source utilizes certain preselected frequencies for power generation and for signaling. It is desirable to detect these frequencies quickly and to be able to disconnect the vehicle from the source if some frequencies are being generated by the vehicle and others are not present on the system. Bandpass filters are coupled to the power converter to detect the preselected frequencies. Wayside transients sometimes encroach on these frequencies with large power spikes causing ringing of the filter circuits and delay in detecting the preselected frequencies. The system includes an active power limiter for limiting the peak amplitude of the signals coupled to the filters without interfering with the signal frequency content or affecting filter operation.

Electrical filter with multiple filter sections

Abstract: An electrical filter having first and second filter sections with respective sets of electrical filter components. These sets of electrical filter components include primary tuning coils which are arranged parallel to a reference axis. An electrical isolation shield is disposed on a reference plane between the first and second filter sections for electrically isolating the sections from one another, the reference plane being orthogonal to the reference axis. The unique configuration of the filter sections allows for the filter sections to be independently tuned while being physically and electrically isolated from one another. The filter sections are then coupled to one another both physically and electrically subsequent to the tuning operation.

Rechargeable/portable multi-voltage dc power supply

Abstract: A rechargeable/portable multi-voltage DC power supply includes an Ni-Cd rechargeable battery set connected to a switching power supply converting circuit, a pulse width modulation circuit, and a filter circuit for providing a regulated output voltage from the filter circuit. A button switch cooperates with a selection circuit and a feedback ratio circuit for selecting a specific output voltage from a plurality of available output voltages. A plurality of light emitting diodes are connected to the selection circuit for indicating the value of the output voltage.

Digital SIGMA - DELTA modulator

Abstract: PURPOSE:To prevent a time delay due to a limiter circuit from being caused by eliminating high-order m-bits other than a VSB of a signal line on the way of an arithmetic loop so as to obtain a limiter characteristic CONSTITUTION:Figure shows a 1-bit D/A converter employing a sigma-delta modulator, and X(z),Y(z),E(z) are respectively an input signal, an output signal and z-conversion of a quantization error The input digital signal X(z) is added to a feedback data at an adder 11 An output of the adder 11 is fed to a quantizer 12, the quantized output signal Y(z) by the quantizer 12 and an output of the adder 11 are subtracted by a subtractor 13 The output data of the subtractor 13 is digitally processed by a filter circuit 15 to be a feedback data The filter circuit 15 consists of an integration device 16 and a 1-clock delay circuit 17 Then a limiter circuit 14 is inserted in an inter-stage of the filter circuit 15

Performance characteristics of an acousto-optic tunable filter for optical spectrometry

Abstract: The development and implementation of the paratellurite (TeO2) acousto‐optic tunable filter as the novel dispersive device are described. It will be demonstrated that this all solid state, rugged filter which contains no moving parts can be used to rapidly diffract white incident light into a selected color beam whose amplitude is kept constant in either pulsed or continuous mode.

Sigma-delta analog to digital converter

Abstract: An analog-to-digital converter has an input for receiving analog signals, a quantizer for producing a digital output of the converter, a first combining node for combining the analog input with a first feedback signal derived from the digital output and producing a first combined signal, and filter circuitry for filtering the first combined signal. The filter circuitry includes at least one filter circuit stage which is not connected to a phase-modifying resistance, and a second combining node for combining an output from the at least one filter circuit stage with a second feedback signal derived from the digital output, and produces a signal for input to the quantizer.

Broadband Filter Circuits using an Extended Suspended Substrate Transmission Line Configuration

Abstract: Suspended stripline has proven to be a low loss transmission line, especially for filters. Making full use of both sides of the substrate, including standard stripline, coupled stripline and microstrip, very broadband components can be realized. This is demonstrated by a 2.5 GHz low-pass filter with high isolation up to at least nearly 17 GHz, high-pass filters up to 30 GHz and a broadband (3.5-7.5 GHz) bandpass without higher pass-bands up to 40 GHz.

Microwave active filter using GaAs monolithic floating active inductor

Abstract: A broadband tunable microwave floating active inductor is proposed. Its application in the microwave active filter is presented. The design technique is to replace the passive inductor in the conventional LC ladder filter by the proposed floating active inductor. These active filters can, therefore, be implemented in full MMIC form. © 1992 John Wiley & Sons, Inc.

Echo cancellation system

Abstract: A circuit architecture suitable for use in a television receiver which effectively performs a ghost or echo cancellation procedure on post-echo components and pre-echo components occurring within the transmission channel. The apparatus features a filter circuit architecture which can be configured under programmed control so as to partition groups of its filter sections to form IIR filters and FIR filters. The filter architecture is suitable for use in multi-circuit configurations and can be used with clustering algorithms to increase the efficiency and optimize the use of the available circuit architecture.

Time-discrete stereo decoder

Abstract: A receiver having a signal path incorporating a tuner, a demodulator circuit for supplying a stereo multiplex signal comprising a baseband stereo sum signal (L+R), a 19 kHz stereo pilot and a stereo difference signal (L-R) which is double sideband amplitude-modulated on a suppressed 38 kHz subcarrier, a sampler for converting an analog signal into a time-discrete signal and a stereo decoder for time-division multiplex decoding of a time-discrete stereo multiplex signal into time-discrete left and right stereo signals. In order to realise an effective selection of the stereo multiplex signal by means of an easily integrable low-pass filter, the stereo decoder comprises a time-discrete halfband low-pass filter circuit having a finite impulse response, with a transition band which is substantially located in the frequency range of said modulated stereo difference signal and with a half-value transfer which is located at the frequency of said 38 kHz stereo subcarrier, which filter circuit has a substantially linear amplitude transfer characteristic as well as a linear phase transfer characteristic in the transition band, said receiver also including an interpolation circuit which is coupled to an output of the filter circuit for converting time-sequential even and odd sampling values of the output signal of the filter circuit into time-sequential pairs of simultaneously occurring sampling values, and a dematrixing circuit coupled to the interpolation circuit for a linear combination of said pairs of sampling values and a compensation of the crosstalk between the left and right stereo signals caused by the filter circuit.

Application of film bulk acoustic resonators

Abstract: Multipole film bulk acoustic resonator (FBAR) bandpass filters are being designed and fabricated on various substrates, including silicon and GaAs. Capable performance has been demonstrated for the large number of system insertions within the low microwave (1-3 GHz) range. Progress in applying FBARs to microwave system applications is reviewed. Refinements in processing of critical piezoelectric films on semiconductor substrates have allowed filter development for specific products to begin. Key tradeoffs involve substrate choice and level of monolithic integration to meet performance and yield requirements. >

Magnetic recording and reproducing device

Abstract: PURPOSE:To improve the quality of reproduced color signal by preparing a narrow-band filter in addition to ordinary brightness and color separating means and switching the filter to the narrow-band filter only in the crosstalk period when the control signal reproduced by other rotary magnetic head makes interference. CONSTITUTION:Two kinds of the wide- and narrow-band filters 23, 24 are prepd. for a low-pass filter circuit 22 and are switched to the narrow-band filter 24 only in the crosstalk period when the control signal reproduced by the other rotary magnetic head 8b going to start scanning exerts interference on the reproduced signal of the one rotary magnetic head 8a in the end period of scanning. The influence of the crosstalk is removed as far as possible by narrowing the pass band of the reproduced color signals during the above- mentioned crosstalk period in this way. On the other hand, the quality of the reproduced color signal is assured by widening the pass band of the reproduced color signal the period when there is no influence of the crosstalks. The interference of the control signal on the color signal is minimized in this way and the quality of the reproduced color signal is improved.

Optical recording and reproducing apparatus with separated high and low frequency servo signals

Abstract: A fixed section of an optical recording and reproducing apparatus is provided with an actuator for optically controlling the fine tracking of a laser beam to be held at a predetermined position, by moving a diverging convex lens of a relay lens in a direction perpendicular to that of the optical axis; first and second filter circuits for separating a tracking error signal outputted from a differential amplifier connected to a two-split light-receiving element into a high-frequency-side signal and a low-frequency-side signal respectively; a first driving control circuit for controlling the driving of a linear motor for moving a movable section of the apparatus on the basis of the low-frequency-side signal separated by the first filter circuit; and a second driving control circuit for controlling the driving of the actuator on the basis of the high-frequency-side signal separated by the second filter circuit.

Stability and performance of notch filter control for unbalance response

Abstract: Many current applications of magnetic bearings for rotating machinery employ notch filters in the feedback control loop to reduce the synchronous forces transmitted through the bearings. The capabilities and limitations of notch filter control are investigated. First, a rigid rotor is examined with some classical root locus techniques. Notch filter control is shown to result in conditional stability whenever complete synchronous attenuation is required. Next, a nondimensional parametric symmetric flexible three mass rotor model is constructed. An examination of this model for several test cases illustrates the limited attenuation possible with notch filters at and near the system critical speeds when the bearing damping is low. The notch filter's alteration of the feedback loop is shown to cause stability problems which limits performance. Poor transient response may also result. A high speed compressor is then examined as a candidate for notch filter control. A collocated 22 mass station model with lead-lag control is used. The analysis confirms the reduction in stability robustness that can occur with notch filter control. It is concluded that other methods of synchronous vibration control yield greater performance without compromising stability.

High Power Active Filter using LC Tuned Filter

Abstract: Usually, to eliminate the harmonics of transmission lines, LC tuned filters are employed to let bypass these harmonic components. But the elimination ability is limited by its damping resistance. Therefore, active filters composed of high frequency PWM converters are desirable. Comparing with the LC tuned filters, the cost would be very high even in high power systems.In this paper, a low cost and high power active filters for a DC transmission system is proposed. It has active filter ability as well as low cost for high power uses. Its main circuit is composed of conventional LC filters in series with square wave voltage inverters. The voltage of the inverter is controlled to cancel the voltage drop of the internal resistance of the LC filter. So the Q factor of the filter can appear infinity. Calculation of the harmonic and the control are done by DSP (TMS 32010). In the experimental system and simulations, two three phase tuned filter 5-th and 7-th are employed. Excellent results under 1% distortion voltage are obtained.

Broadband matching network

Abstract: A broadband matching network closely matches the output impedance of a broadband amplifier to the input impedance of a laser over a broad frequency band to facilitate efficient transfer of power therebetween. As a result, the broadband amplifier does not have to generate high output power levels that cause intermodulation distortion. The matching network includes a pair of matching transformers having toroidal cores and a filter circuit.

Switched-current wave analog filters

Abstract: A novel approach to the realization of switched-current (SI) filters is presented. This approach relies on wave filter functions, which the authors have proved to be particularly suitable for switched-current implementations owing to the simplicity of SI realization for summation, scaling, and time delay operations. Filter design using this concept requires a limited library of modular building blocks (adaptors and delay elements). The total size, power consumption, and dynamic range of these building blocks can be made nearly independent of the filter function coefficient values, which enables the practical realization of wave SI filters over a wide range of bandwidths. >

A novel inverter with sinusoidal voltage and current output

Abstract: Output voltages of a conventional voltage-source pulse-width-modulated (PWM) inverter applied to AC motor drive systems contain high-level switching frequency ripples due to the PWM operation, while output currents are kept nearly sinusoidal. The high-level harmonics, in the output voltage cause acoustic noises and iron losses. To improve the output voltage waveforms, the authors propose a novel inverter with sinusoidal voltage and current outputs, which has an LC passive filter and an active filter function. The principle of the inverter and some simulation results are shown. Simulation results show satisfactory operation when it is applied to a field-oriented vector control system, for an induction motor. >

Sensing potentiometer unit e.g. for vehicle accelerator pedal control - has pairs of potentiometers linked to control unit via filter circuits to eliminate ageing effects of potentiometer tracks.

Abstract: Each vehicle function normally monitored by sensors has a second, similar sensor to provide a parallel, redundant signal. The two signals are compared via filter circuits and a control circuit. The settings of the vehicle controls etc. are determined by the signal shapes from the filter circuits and not by mere potentiometer levels. Simple low-pass filter circuits are used to process the sensor outputs. The control circuit can switch different reference signals to the sensors to monitor the sensor reaction. Periodical self-analysis reduces failure risk. ADVANTAGE - Accurate sensor function, not affected by potentiometer track wear.

DC motor control using frequency and pulsewidth modulation

Abstract: The flow of power through a field effect transistor to a DC motor is controlled by the output of a frequency modulator having a low frequency pulsed signal applied to one input thereof and a high frequency pulsed signal applied to a second input thereof. The pulse width of each "on" pulse of the low frequency pulsed signal is varied in response to a signal representing a desired motor speed. Optionally, the pulse width of each "on" pulse of the high frequency pulsed signal can also be varied in response to the signal representing the desired motor speed. A filter circuit can be employed to prevent rapid changes in the pulse width of the low frequency pulsed signal. Similarly, a filter circuit can be used to avoid rapid changes in the pulse width of the high frequency pulsed signal. A freewheeling diode can be used to minimize inverse voltage spikes across the motor.

Recording device and video device using the same

Abstract: A recording device comprising, a wind pressure sensor either foraged integral with the microphone or disposed at the vicinity of the microphone and detecting the wind pressure acting thereon; a recording circuit; a filter circuit which cuts off low sound components corresponding to the wind sound; a selection circuit which sends out the sound signal collected by the microphone to the recording circuit via the filter circuit in response to a control signal and, when no control signal is received, sends out the sound signal to the recording circuit while bypassing the filter circuit; and a control circuit which generates the control signal when the signal from the wind pressure sensor exceeds a predetermined level.

Delay circuit manufacturable by semiconductor elements

Abstract: A delay circuit includes a first filter circuit responsive to an input signal and outputting a first output signal having first-order low pass characteristics with respect to the input signal, a second filter circuit responsive to the input signal and outputting a second output signal having first-order high pass characteristics with respect to the input signal, and a difference computing circuit responsive to the first and second output signals and outputting a difference signal therebetween as an output signal of the delay circuit. By the constitution, it is possible to reduce an attenuation factor irrespective of the input signal frequency and obtain a relatively long and easily changeable delay time in a wide frequency band.

Apparatus for suppressing pseudo-contours in video signals

Abstract: An image signal processing device includes a luminance information detecting circuit which detects luminance information on an object and a filter circuit to which an image signal is supplied from an image sensing system. The filtering characteristic of the filter circuit is arranged to be switched from one characteristic over to another according to the detection output of the luminance information detecting circuit, so that the generation of a pseudo-contour can be prevented.

Living body monitoring device

Abstract: PURPOSE:To monitor the body movement such as heart beat, aspiration and turning-over in bed with low cost and without deteriorating the humidity transmissivity and hygroscopicity of the bedclothes by allowing the title living body monitoring device to consist from a flexible piezoelectric element, filter circuit for allowing only the component having a prescribed frequency, amplifying circuit, and a counting circuit. CONSTITUTION:A flexible piezoelectric element 9 is formed by forming a high polymeric piezoelectric material into a thin film form and attaching each flexible electrode film on both the surfaces and shaping this thin film into a tape form, thus the manufacturing cost can be cut, and mass production is permitted, and this film body is fixed on the surface of a mattress 6. When the piezoelectric element 9 is deformed by the body movement such as heart beat, aspiration and turning-over in bed, a voltage is generated by the piezoelectric effect by the piezoelectric element 9. Only the component having the prescribed frequency among the generated voltage outputs is allowed to pass through a filter circuit 10, and after the amplification by an amplifying circuit 11, the body movement such as the number of heart beat, number of aspiration, and the turning-over in bed is counted by counting the number of times in which the output signal of the amplifying circuit becomes over a previously determined threshold value by a counting circuit 12, and the counting value is displayed on a surface part 13.

Design of a highly stable electromagnet power supply

Abstract: A method for designing a highly stable electromagnet power supply combining the 12-pulse phase-controlled rectifier (PCR), passive filter, and transformed active filter is investigated. The PCR system is analyzed, and passive filter parameters are designed from this analysis. A phase-locked voltage control circuit with a fast dynamic characteristic is analyzed, and an optimal constant proportional-integral and measurable variable feedback plus feedforward (PIMF) current controller is designed using a time-weighted quadratic performance index. It is shown via experimental results that the proposed design method gives good performance. >

Investigation of passive bandpass filters using MMIC technology

Abstract: The idea of dedicating an MMIC processing run solely for passive filter components is explored. After going through preliminary design procedures, key parameters such as tap position, resonator length and coupling gaps can be studied in a controlled experiment to ascertain the optimal design. The MMIC fabrication process allows the design engineer the luxury of numerous filter designs within a single iteration and is extremely cost effective when compared with an equal number of hybrid MIC designs. MMIC filters are extremely small, highly reliable, and utilize existing processing technology. Passive filters are important when prime power consumption is limited as in advanced phased arrays for air and space applications. Ku-band MMIC parallel coupled, elliptical, and interdigital designs are investigated. The interdigital type yielded state-of-the-art performance and required the least substrate area. >

Low frequency filter in a monolithic integrated circuit

Abstract: A low-pass filter circuit is disposed on a monolithic integrated circuit. An operational amplifier receives a reference potential and drives three parallel stacked diode paths into a current supply. One of the stacked diode paths conducts the vast majority of the current allowing the transistors of the other two stacked diode paths to operate in a sub-threshold region and represent an extremely high resistance. The high resistances in combination with a low value capacitor realizes a low-pass filter on the monolithic integrated circuit.