Showing papers on "Electronic filter published in 1986"

Passive and Active Filters: Theory and Implementations

Abstract: Fundamentals of Network Synthesis Filter Approximation and Frequency Transformations Passive Filter Synthesis Design of Resistively Terminated Networks Active Filter Synthesis: Fundamentals Sensitivity The Active Biquad Realization of Active Two-Port Networks Design of Broadband Matching Networks Theory of Passive Cascade Synthesis General Theory of Compatible Impedances. Appendixes.

Active filter for reactive power and harmonics compensation

Abstract: This paper describes a three-phase active filter aimed at the compensation of reactive power and current harmonics of a symmetrical load. The filter employs an inductor for energy storage and a two-quadrant PWM bridge converter.

Active filters for 1 MHz power circuits with strict input/output ripple requirements

Abstract: As the switching frequency of a dc-dc converter is raised from 100 kHz to 1 MHz, one would expect the energy storage elements of the circuit to be correspondingly reduced in size. If the circuit must meet input and output ripple requirements of the nature of MIL-STD-461B CEO3, however, the advantage of a higher switching frequency is significantly offset by the higher filter attenuation levels required. This paper discusses the use of active filters, in conjunction with minimal passive filters, to achieve the required ripple levels with a much smaller overall volume. Working active filters with gains in excess of 100 at 1 MHz are also presented.

Harmonic current compensator composed of static power converter

Abstract: A new harmonic current compensator composed of a static power converter was developed. It is composed of two voltage-type inverters in a multiplex configuration, this new compensator has a number of features that make it superior to the conventional passive filter composed of an AC reactor and a capacitor. This paper describes the principle of harmonic current compensation, the capability which the converter is required to have as compensator, the compensator's features and a trial production equipment. The important factor which are essential to a compensator, such as main circuit configuration, components, control circuit, control technique, etc. were discussed. Also the test results of a compensation characteristic were presented. Excellent characteristics of the new harmonic current compensator were verified through an experiment.

UHF Bulk-Acoustic-Wave Filters Utilizing Thin ZnO/SiO2-Diaphragms on Silicon

Abstract: This paper reports on a temperature-stable bulk-acoustic-wave (BAW) filter consisting of a thin ZnO/SiO2 composite diaphragm structure on a silicon wafer. To make a theoretical treatment of the BAW filter possible, the constants for the distributed-parameter equivalent circuit extended to the composite structure are derived from analysis of the dispersion curves for waves propagating along the ZnO/SiO2 diaphragm. Some actual filters are designed and analysed using the equivalent circuit. The measured characteristics of a 578-MHz BAW filter of the two-coupled-resonator type fabricated on silicon are reported and discussed. The results demonstrate that the measured characteristics resemble the theoretical ones but that the insertion loss is as high as 12 dB.

Electrical filter with adjustable RC product

Abstract: A continuous time electrical filter fabricated as an integrated circuit includes capacitors (CO,CN) and resistors (R1,R2). Since capacitors and resistors are difficult to integrate with accurately defined values a trimming circuit is provided which operates switches (S1-SN) to select appropriate ones of the capacitors (CN) to accurately define the cut-off frequency of the filter. The trimming circuit comprises a capacitor (TC2) which is charged through a resistor TR1 during a first period and which is discharged in incremental steps by a capacitor (TC1). The number of incremental steps is counted by a counter (11) and transferred to a register (13). The outputs (S1-SN) of the register control the switches (S1-SN). Instead of adjusting the value of the capacitors in the filter, the values of the resistors may be adjusted. If this is done a convenient procedure is to short out selected portions of the resistors. More than one capacitor or resistor may be adjusted using a single counter and register.

Low‐pass filters for signal averaging

Abstract: Detailed comparison of the settling time‐noise bandwidth products of 31 types of low‐pass filters demonstrates that the settling time‐noise bandwidth product is the figure of merit for such filters when the goal is averaging. Common filters such as Butterworth, elliptic, and Chebyshev are found to be unusable for such purposes while others, such as Bessel filters, offer only moderate figures of merit. The best reported analog low‐pass filter differs from ideality by only about 11%. The optimum analog low‐pass filter, having continuous, rational transfer function, is unknown.

Integrated filter circuit having switchable selected parallel filter paths

Abstract: An integrated filter circuit including at least integrated resistances and integrated capacitances, said integrated filter circuit comprising a plurality of filter circuits connected in parallel and in which at least either resistance values or capacitance values are different, a switch for switching said parallel filter circuits, and means for controlling said switch to select one of said parallel filter circuits.

Vehicle height control apparatus

Abstract: A vehicle height control device that includes a pressure sensor 28 for detecting the pressure of compressed air supplied to pneumatic shock absorbers 10 for pneumatically bearing the load of a vehicle loads applied through the wheels. A control circuit 30 is included for controlling vehicle height based on the pressure detected by the pressure sensor 28. A waveform shaping circuit is connected between the control circuit 30 and the pressure sensor 28 and shapes the waveform to moderate the pressure change while the pressure is rising to a greater degree than while the pressure is dropping. The waveform shaping circuit includes a passive low-pass filter circuit 38, an active low-pass filter circuit 52 and a pair of diodes 70 and 72. The diodes 70 and 72 connected to the active filter circuit 52, allowing rapid capacitor discharge during decreases in signal amplitude while maintaining a slow discharge rate during decreases in signal amplitude.

Antenna coupling circuit

Abstract: PURPOSE:To obtain a perfect isolation between transmission and reception by providing a receiving trap circuit between a transmitting circuit and a transmitting filter circuit, and providing a transmitting trap circuit between a receiving circuit and a receiving filter circuit. CONSTITUTION:A transmitting output of a transmitting circuit 6 is inputted from a Tx input terminal, passes through a transmitting filter circuit 8 and reaches a point A. In this case, even if a filter capacity of a receiving filter circuit 10 is not perfect against a transmission frequency fT of a transmitting output, a transmitting trap circuit 12 of its post-stage is set so as to be resonated by the transmission frequency fT, and by its resonance operation, a resonance impedance of a trap becomes low. On the other hand, at the time of reception, when a receiving power from an antenna ANT 7 reaches the point A, even if a filter capacity of a transmitting filter circuit 8 is not perfect against a reception frequency fR of a receiving output, a receiving trap circuit 11 of its post-stage is set so as to be resonated by the reception frequency fR, and by its resonance operation, the resonance impedance of the trap goes to low. In such a way, a good duplex communication can be executed.

Restoration for sampled imaging systems.

Abstract: Digital image restoration requires some knowledge of the degradation phenomena in order to attempt an inversion of that degradation Typically, degradations which are included in the restoration process are those resulting from the optics and electronics of the imaging device Occasionally, blurring caused by an intervening atmosphere, uniform motion or defocused optics is also included Recently it has been shown that sampling, the conversion of the continuous output of an imaging system to a discrete array, further degrades or blurs the image Thus, incorporating sampling effects into the restoration should improve the quality of the restored image The system transfer function (the Fourier transform of the point spread function), was derived for the Landsat Multi-Spectral Scanner (MSS) and Thematic Mapper (TM) systems Sampling effects were included, along with the relevant optical, instantaneous-field-of-view and electronic filter data, in the system analysis Using the system transfer function, a least-squares (Wiener) filter was derived A Wiener filter requires the ratio of the power spectra of the scene and noise, which is often, for simplicity, assumed to be a constant over frequency Our restoration includes models for the power spectra which are based on the study of several different types of Landsat scenes The Wiener filter is then inverse Fourier transformed to find a restoration filter which is spatially windowed to suppress ringing Visual evaluations are made of the restored imagery

A Fully Integrated Filter Circuit for VCRs

Abstract: In order to miniaturize VCRs, various components have been integrated with semiconductor circuits, but to date video filters such as luminance LPFs, emphasis filters, and chrominance BPFs have not been integrated. We have recently developed an integrated filter circuit for processing video signals. The new circuit was fabricated using a new bipolar process called the Hiplanar process and has been applied to a dynamic emphasis IC for VCRs. Because this filter circuit operates up to 10 MHz, any video filter can be integrated by the same means.

X-ray diagnosing device

Abstract: PURPOSE: To drive a space high pass filter even during movement of a scene in radioscopic operation. CONSTITUTION: An X-ray tube, an X-ray image intensifier, a television camera, a processing circuit, and a central processor are provided; and this processing circuit is provided with a monitor 7 and a space frequency filter provided with a storage means 10, a filter circuit 12, a passage time compensation circuit 13, and a mixing stage 14 which mixes output signals of both circuits 12 and 13. In this X-ray diagnosing device, a movement detector 11 is connected to the storage means 10 and a television camera 5, and the movement detector 11 controls a mixture ratio in the mixing stage 14 so that the filter action in a radioscopic scene of less movement is stronger than that in an area where an object is moved.

Clock recovery and retiming scheme with saw filter phase trimming to achieve desired system phase adjustment

Abstract: A clock recovery and data retiming circuit is disclosed which utilizes a SAW filter to form the recovered clock signal. The phase shift of the received data signal associated with various attenuation and distortion effects of the communication channel is compensated for and removed from the retimed data signal by adjusting the phase of the SAW filter.

Load current detecting method of switching regulator

Abstract: PURPOSE:To simplify a construction inexpensively by detecting a load current value by utilizing counterelectromotive force of the resistance of a reactor of a filter circuit placed on a switching regulator. CONSTITUTION:A main switching element 6 such as a power transistor outputs an output side DC voltage controlled or a load current controlled by variably controlling the time of ON and OFF through a controller 7 while continuously opening or closing an input side DC voltage. Master and slave reactors 9, 13 are for smoothing the load current, and the reactor 13 is also used as detecting the load current. The potentials of the voltage dividing point (a) of the dividing resistors 11, 12 and the point (b) of the load side terminal of the reactor 13 are input to the controller 7.

The Development of a Surface Mount Hybrid if Section Using Low Loss SAW Filters

Abstract: A thick film hybrid circuit incorporating two low loss group-type unidirectional transducer (GUDT) SAW filters was developed for use in a receiver IF section centered at 310.7 MHz. The two filters were cascaded with a preamp and a buffer amplifier on one hybrid to achieve IF gain and filtering. The low loss GUDT SAW filter was designed using a Hamming apodization. Performance, assembly and reliability were enhanced by taking a surface mount hybrid approach. A leadless chip carrier package for the SAW device was designed and optimized for low loss and high out of band rejection. Surface mount chip inductors were evaluated and optimized for match and insertion loss. A high temperature hermetic seal process was developed for the custom SAW package and extensive environmental tests were performed on both the packaged SAW and the fully assembled hybrid to insure a high degree of reliability. Packaged filter losses were less than 6.5 dB per filter. Rejection at the image frequency for the hybrid IF section exceeded 90 dBc. Typical peak-to-peak passband ripple was .2 dB.

Video signal reproducing apparatus for reproducing recorded video signal from a magnetic recording medium

Abstract: A video signal reproducing apparatus for reproducing a recorded video signal from a magnetic recording medium comprises a reproducing circuit for reproducing a recorded frequency division multiplexed signal of an angle modulated luminance signal and a frequency converted carrier chrominance signal which has been frequency-converted into a low frequency band, a demodulating circuit for obtaining a reproduced luminance signal, a filter circuit for filtering a specific frequency component within the reproduced luminance signal, a level detecting circuit for detecting an output signal level of the filter circuit, a frequency converter circuit for obtaining a reproduced carrier chrominance signal, and a level controlling circuit for controlling the level of the reproduced carrier chrominance signal based on an output detection signal of the level detecting circuit.

SAW Filters Using Three-Transducer Configuration with Outer Transducers Weighted by Comb-Shaped Characteristics

Abstract: New outer transducers which comprise pairs of elemental transducers with comb-shaped characteristics are studied for 3-transducer configuration to obtain good rejection in the stopband and good triple transit suppression. A designing method is also developed; these outer transducers are arranged to synthesize the passband shape of the filters, while the central transducer is apodized for matching in the pasband. Application of these transducers to a SAW filter of 400 MHz center frequency is discussed. Group delay of less than 10 n secpp is obtained, while a 10 dB loss is obtained in 50 Ω systems.

Positioning circuit for magnetic head

Abstract: PURPOSE:To prevent a track traceability characteristic from being deteriorated, by adding a filter circuit including two integrators on a magnetic head position control loop. CONSTITUTION:The filter circuit is constituted of a first integrator 2 of differential type, a second integrator 3 of the differential type similarly, and an adder 4. To the first integrator, a filter input signal 1 and a filter output signal 5 that is the output of the adder 4 are inputted, and to the second integrator, the filter input signal 1, the output of the first integrator 2, and the filter output signal 5 are inputted, and to the adder 5, the filter input signal 1 and the output of the second integrator 3 are inputted. Thus, by adding the filter circuit including the two integrators on the magnetic head position control loop, it is possible to realize a sufficient phase lead quantity without reducing stability at a mechanical resonance point according to the excessive increase of a high-pass area gain on an open loop gain characteristic, or resulting the deterioration of the track traceability characteristic which causes the excessive lowering of a low- pass area gain. In such a way, a stable magnetic disk device with a superior positioning characteristic can be obtained.

Circuit arrangements for modifying dynamic range using variable combining techniques

Abstract: @ The circuit arrangements for modifying the dynamic range of signals, particularly compressors and expanders for use in noise reduction compander systems, have the advantages of fixed band characteristics (variable attenuation throughout all or part of the frequency band) and sliding band characteristics (variable attenuation through part of the frequency band achieved by a variable pass filter), without the disadvantages normally inherent in each characteristic. The outputs of fixed band and sliding band circuits (74 and 72) variably selected by a combining means (60) operated by a control circuit (70) which senses signal frequencies and/or levels, the circuits (74 and 72) operating in generally the same level range and at least a partial overlapping in frequency range, optionally also in parallel with a filter circuit (76) with fixed characteristics.

Audio amplifier system

Abstract: A power supply and audio amplifier system including an audio amplifier system adapted to receive an audio signal (AD) which is supplied to an attenuator (70) which receives the signal and selectively attenuates the signal which is then supplied to a buffer (80) and filter circuit (90) to condition the signal. The attenuated, filtered signal (99) is then supplied to a modulator (100) where it is converted to a square wave signal having a pulse width which is a function of the level of the audio signal. The square wave pulse signal is then supplied to push-pull converter (110) to generate an alternating current signal which is supplied to the primary coil (P3, P4) of a transformer (T3, T4), an amplified output signal is supplied to a load (L) from the secondary coil (S3A, S3B, S4A, S4B) of the transformer. The load characteristics are analyzed and a loading signal is supplied to a clipper circuit (220) which prevents the output from exceeding selected load limits.

Floppy disk driver

Abstract: PURPOSE:To cope with the change of characteristics of an R/W head by putting a correction circuit consisting of passive individual parts between the R/W head and a hybrid IC constituting a reproduction circuit without changing the number of lead terminals of the hybrid IC. CONSTITUTION:The reproduction analog given from an R/W head 1 passes through a correction circuit 2 and is supplied to an amplifier circuit via an input circuit 3. The amplified reproduction signal passes through a filter circuit 6 for reduction of noises and is differentiated by a differentiation circuit 7. This differentiated signal is converted into a digital signal by a comparator 8. An error pulse of the digital signal is eliminated by a time domain filter 9. Thus a digital reproduction signal is obtained. A reproduction circuit 11 reaching the filter 9 from the circuit 3 is converted into a hybrid IC. The frequency characteristics of the head 1 and circuits 2 and 3 can be changed within a certain range by varying correction resistances r1 and r2 of the circuit 2. Thus the circuit 11 can be shared by various types of R/W heads.

Circuit arrangement for detecting motion in a television picture

Abstract: To detect horizontally moving portions of a TV frame formed from two adjacent fields, the vertical local frequency at a vertical edge of the moving portion of the picture is measured with a narrow-band-pass filter circuit which is tuned to the local frequency of the comblike structure at ta vertical edge of staggered lines of the two fields of the frame. When such an edge structure is detected, the circuit delivers a detection signal.

Active filter unit for electric railcar

Abstract: PURPOSE:To reduce a ripple voltage of a specific frequency by a small-sized, light-weight unit by sorting the rippled voltage of the specific frequency from a voltage between terminals of filter capacitors, and superposing it on a DC voltage in the polarity of reverse phase. CONSTITUTION:An input filter 9 sorts a ripple voltage of a specific frequency from a voltage between terminals of capacitors 6 of a DC filter circuit, and applies it through an insulating transformer 10 to a band pass filter 11. An amplifier 12 sets the phase of the output voltage of the filter 11 in reverse polarity, and applies it through a transformer 13 to a DC side. An overcurrent detector 15 turns ON an input shortcircuit switch 17 when the output of a current transformer 13 becomes the upper current limit value or higher. An overvoltage detector 16 turns ON the switch 17 when the output voltage of the amplifier 12 becomes the upper voltage limit or higher, and turns OFF an output switch 18.

Circuit for producing a video signal representing a measuring signal

Abstract: A circuit for producing a video signal representing a measuring signal is already known, said circuit comprising a video storage circuit, a horizontal address control circuit for controlling said video storage circuit, a circuit for producing a vertical signal and a comparator circuit which, when the vertical signal essentially corresponds to a signal derived from the video storage circuit, produces a comparison signal representative of a point of the measuring signal in the instantaneously produced line of the video signal. For the purpose of improving the measuring signal representation quality, the invention provides the feature that a video D/A converter and a low-pass filter circuit are inserted between the video storage circuit and the comparator circuit.

Video effect device

Abstract: Effects unit for video studios, discotheques and the like, comprising an electronic filter and control unit which, in conjunction with a feedback arrangement, makes it possible to generate abstract images. The parameters of the feedback are controlled, particularly the frequency response. Music-controlled influencing of these parameters with the aid of voltage-controlled filters in the video-frequency range. Furthermore, a control device for the brightness.

Rc active filter circuit

Abstract: PURPOSE: To simply trim the characteristic of an RC active filter by using plural switches switched by an output bit signal from a PROM so as to short- circuit or open resistors. CONSTITUTION: The PROM 2 and the plural switches short-circuiting or opening resistors or capacitors through an output signal of the PROM 2 are provided. Even with the dispersion of the resistors R1, R2 and the capacitors C 1 , C 2 , the RC active filter having a characteristic close to the desired characteristic is formed by using a switch so as to select the resistance of resistors R 11 , R 12 ∼R 1n :R 21 , R 22 ∼R 2n . That is, the characteristic of the RC filter is trimmed. Moreover, even when lots of RC active filters exist on one and same chip, switches Sij are switched by the same PROM output bit in selecting the ratio of the resistance of the resistors to be constant. COPYRIGHT: (C)1988,JPO&Japio

Method of configuring N-TH degree switched capacitor filter

Abstract: An n-th degree switched capacitor filter having transfer characteristics expressed by a transfer function H(Z) can be configured by expanding the transfer function H(Z) to an n-element linear simultaneous state equation of n state voltages inclusive of an output voltage. The coefficients of the linear state equation a 11 to a n2 , b 11 to b nn are determined in a range within which the filter circuit can be configured by hardware and further each state voltage is below a maximum output voltage. In practice, the filter is configured by plural leapfrog type differential operational amplifiers having base capacitors C o , plural transmission gates, and plural electric charge transfer capacitors C T so as to determine each coefficient on the basis of ratios C T /C o . The filter is realized by a monolithic integrated circuit (IC) and provided with a higher signal-to-noise (S/N) ratio and a wider dynamic range without deteriorating electrical characteristics and increasing cost.

Optical reception circuit

Abstract: PURPOSE: To prevent erroneous reception caused by noise and to execute the first transmission to a receiving state at high speed by providing a filter circuit having a time constant switching function in a DC voltage circuit which impresses to an APD. CONSTITUTION: A titled circuit provides the voltage circuit 2 which applies a voltage to an avalanche photodiode(APD) 1 and receives light beam supplied to the APD 1 under the condition where the voltage is impressed by the voltage circuit 2 as an electrical signal. And the filter circuit 5 having the time constant switching function is provided between the output end of the voltage circuit 2 and the APD 1 and an electric field effect transistor FET which constitutes one of the time constant circuits is provided in the filter circuit 5, then the electric field effect transistor FET is controlled by a received signal so as to alter the connection resistance of the transistor FET. Thus a comparatively small capacity will serve the voltage circuit 2 and the first transition of the reception circuit is made to be at high speed. COPYRIGHT: (C)1988,JPO&Japio