Showing papers on "Electronic filter published in 1981"

Electronic filter design handbook

Abstract: Chapter 1: Introduction to Modern Network Theory Chapter 2: Selecting the Response Characteristic Chapter 3: Low-Pass Filter Design Chapter 4: High-Pass Filter Design Chapter 5: Bandpass Filters Chapter 6: Band-Reject Filters Chapter 7: Networks for the Time Domain Chapter 8: Refinements in LC Filter Design and the Use of Resistive Networks Chapter 9: Design and Selection of Inductors for LC Filters Chapter 10: Component Selection for LC and Active Filters Chapter 11: Normalized Filter Design Tables Chapter 12: Introduction to Digital Filters Chapter 13: Finite Impulse-Response Filters Chapter 14: Infinite Impulse-Response Filters Chapter 15: Multirate Digital Filters Chapter 16: Digital Filter Technology Chapter 17: Switched-Capacitor Filters Chapter 18: Introduction to Microwave Filters APPENDIX A: DISCRETE SYSTEMS MATHEMATICS APPENDIX B: SOFTWARE SUMMARY INDEX

Electrical filter circuit operated with a definite sampling and clock frequency fT which consists of CTD elements

Abstract: The invention relates to an electrical filter circuit operated with a definite sampling and clock frequency fT, such filter being made up of CTD elements, and having at least one bipolar or quadripolar resonator in the form of a self-contained conductor loop (for example, C1, C2) with unidirectional transmission behavior. Differences in the transfer capacitances of such circuits are reduced, as far as possible, in order to thereby simplify integrated manufacture as far as possible, by positioning the frequency band to be filtered out at a frequency position which lies above half the clock frequency (fT /2), or in the range from fT /2 through 3fT /2.

Equivalent Circuit Modeling of Stacked Crystal Filters

Abstract: The traditional stacked crystal filter (SCF) is composed of two bonded piezoelectric plates with a common ground plane at the bond line. Thus, the filter input and output terminals are largely isolated by the ground plane electrode to provide a high degree of off resonance rejection. In operation, the system is driven to resonance by the input resonator (transducer) and the resulting energy is radiated to the output plate which acts as a receive transducer to couple the energy to the external electrical circuit.

Monitoring system for the capacitor batteries of a three-phase filter circuit

Abstract: A system for monitoring the capacitor batteries of a three-phase filter circuit. Each capacitor battery is formed of a plurality of parallel legs each having a plurality of sectional capacitors which are connected in series with fuses. Adjacent ones of the sectional capacitors are coupled to one another. In a three-phase system, three capacitor batteries are coupled to one another in a Y-circuit configuration, the Y-circuit node being coupled to a reference potential, illustratively ground. The magnitude and phase of the fundamental frequency component of the current flowing from the Y-circuit node to the reference potential is monitored, variations therein being evaluated to identify defective sectional capacitors. Only variations in the Y-circuit node current which occur rapidly will trigger fault signals, thereby preventing false indications resulting from variations in temperature.

Sound reproduction device

Abstract: A sound reproducing device particularly adapted for use in the passenger compartment of an automobile and having improved stereo separation and symmetrical frequency characteristics. The device includes a high-pass filter circuit for passing, when a leakage signal occurs, a signal of equal frequency component to the leakage signal, an attenuation circuit for attenuating the level of the signal passed through the filter circuit to the level of the leakage signal, and a phase inverting circuit for inverting the phase of the signal thus attenuated so as to be opposite to that of the leakage signal, thereby to cancel out the leakage signal.

Design of active filters independent of first-and second-order operational amplifier time constant effects

Abstract: A practical method of designing active filters in which the transfer function is independent of both first- and second-order operational amplifier time constant effects is presented. Neither matched operational amplifiers nor a tuning procedure dependent on an active parameter is required. The active portion of these filters is universal and readily integrable since it is comprised of conventional operational amplifiers and resistors. The method can be used to design a filter with any realizable transfer function of any order. Several new filters obtained from this method are introduced and evaluated both theoretically and experimentally. These configurations contain popular passive structures and the new universal active circuits. The significant improvements in filter performance of these new filters is demonstrated in this evaluation.

Monitoring system for an LC filter circuit in an AC power network

Abstract: A monitoring system for measuring the phase currents of a filter circuit, the monitoring system having current measuring transformers coupled to respective filter sections for suppressing the harmonic content. Voltage measuring transformers are provided for measuring the network phase voltages, each such voltage measuring transformer being coupled to an electronic filter simulator and a filtering section for suppressing harmonic content. The fundamental frequency component of the measured phase currents and the simulated phase currents are conducted to transient comparator circuitry which is coupled to indicating and triggering circuitry having individual counter stages. Only rapid variations between the measured and simulated phase currents will result in fault indications, thereby preventing false indications resulting from variations in temperature.

Rotor position detecting method for brushless direct current motor

Abstract: PURPOSE:To eliminate a position detector signal line and to stabilize operation regardless of the ambient temperature by detecting the position of a rotor via an integrating filter and differential filter utilizing voltage wave form induced in a stator coil CONSTITUTION:When driving a brushless direct current motor having a permanent magnet rotor by a transistor circuit, induced voltages in each stator coil of multi-phase connection are applied to terminals a3, b3, c3 and are inputted to one terminal of comparators a5-c5 via filter circuits a4-c4, each having a integrating filter and differential filter, while the voltage of each filter is synthesized by a neutral point voltage synthesizer circuit 7 and is inputted to the other terminal of the comparators a5-c5 This output is processed in a logic processing circuit 6 and drives transistors provided for each phase This construction largely stabilizes detection of the rotor position without providing Hall elements

Model and filter circuit for modeling an acoustic sound channel, uses of the model, and speech synthesizer applying the model

Abstract: Speech and music phonation formed by spectral formants is synthesized by a composite filter containing parallel filters in cascade. The composite filter design is generated by partial-function expansion of the approximate sound channel transfer function ##EQU1## and the composite filter is implemented with mutually adjacent formants in cascade filter elements.

Pilot signal recording and reproducing system

Abstract: A pilot signal recording and reproducing system comprises a frequency generating circuit for successively generating a first frequency, a third frequency, a second frequency, and a fourth frequency in this order or in a reverse order for every recording unit of one track, where the first and second frequencies are mutually separated frequencies, selected from a first frequency group, and the third and fourth frequencies respectively are frequencies approximately equal to the first and second frequencies, selected from a second frequency group, a recording device for recording a frequency obtained from the frequency generating circuit as a pilot signal together with an information signal onto a recording medium, a comb filter for frequency-selecting pilot signals recorded on both sides of a track which is to be reproduced, where these pilot signals have mutually different frequencies and are included as crosstalk within a reproduced signal reproduced from the recording medium, a control circuit for controlling a delay time of a delay circuit within said comb filter and first and second filter circuits for respectively discriminating and separating pilot signals having mutually different frequencies obtained from the comb filter.

Digital design of two-dimensional LC structures

Abstract: A systematic approach to the design of two-dimensional digital filters from one-dimensional analog transfer functions is presented. The procedure uses the concept of generalized delay units to obtain a ladder realization from a given lossless transfer function.

Passive CCD resonator filters

Abstract: Novel passive recursive CCD bandpass filters have been realized using standard two-level-polysilicon gate NMOS technology. A Chebyshev bandpass (w/SUB rel,/ /SUB 3/ /SUB dB/=3.1 percent) and a fully integrated CCD signal filter with an extremely narrow 3 dB bandwidth of 97 Hz (Q=1350) at 131.85 kHz center frequency were implemented by means of cascaded CCD resonators. The latter chip contains the necessary clock generation and biasing circuitry realized with dynamic circuit techniques to achieve low power consumption (40 mW per filter). Performing all filtering operations exclusively in the charge domain ensures filter passivity. An extremely stable center frequency and a bandwidth independently controlled by a capacitance ratio are the special advantages of such filters.

Narrow-band tunable optical filter made of a CdGa2S4 single crystal

Abstract: An optical polarization filter was constructed from a CdGa2S4 single crystal. This filter was temperature-tunable in the range 487–580 nm. Its pass band was 2 nm and the transmission at the maximum of the spectral characteristic was 48%. The filter was also capable of withstanding high-power laser radiation (damage threshold 32 MW/cm2).

Current mode biquadratic active filter

Abstract: A configuration of two transistors (Q1, Q2) and two capacitors (C1, C2) provides a current mode second-order active filter for IC implementation with low-pass, bandpass and high-pass capabilities. The filter frequency is tunable over a wide range, independently of filter Q and gain, by varying a DC bias current (Ibias1). The filter can provide one-port impedance functions, and two-port voltage, current and impedance transfer functions. With the addition of a second biasing current source (Ibias2), the filter Q can be controlled by adjusting the ratio of the two biasing current sources. Enhanced dynamic range and large signal performance can be achieved by the addition of linear resistors (R1, R2), with trade-offs in tunable frequency range and frequency linearity.

Impedance transformation network for a SAW filter

Abstract: The IF section of a television receiver includes an amplifier having an input terminal for receiving an IF signal and an output terminal at which an amplified version of the IF signal is developed and a SAW filter having two input terminals, one of which is connected to AC signal ground, for receiving the amplified IF signal and an output terminal for providing a modified IF signal having a bandpass characteristic determined by the SAW filter. An impedance transformation network is coupled between the output terminal of the amplifier and the input terminal of the SAW filter for increasing the effective load impedance of the amplifier and for decreasing the output impedance of the drive arrangement. The former aspect of the impedance transformation network allows a transistor with lower current supplying capabilities to be employed. The latter aspect of the impedance transformation network tends to reduce undesired voltages developed in response to reflections between the transducers of the SAW filter. Specifically, the impedance transformation network includes an inductor connected between the output terminal of the amplifier and the AC signal ground, a capacitor connected between the output terminal of the amplifier and the input terminal of the SAW filter and a resistor connected between the input terminal of the SAW filter and the AC signal ground. Desirably, the capacitance of the capacitor is in the same order of magnitude as the input capacitance of the SAW filter and the inductance of the inductor is selected to provide a resonance with the effective capacitance in the passband.

Piezoelectric resonator with integrated capacitances

Abstract: If a piezoelectric crystal is used in circuits containing ICs with low supply voltage, the additional capacitors required in oscillator or filter circuits cannot be implemented as junction capacitances. To eliminate the need for additional discrete capacitors, these capacitances are implemented with additional films on the crystal.

Filter circuits having transformers as filter elements

Abstract: Filter circuits of the type having inductance and capacitance elements, wherein the number of magnetic components is reduced by using two transformers to perform the functions of four individual inductors. Each transformer has one end of the primary winding connected to one end of the secondary winding, and a pi or T equivalent circuit in which one of the inductance values is equal in magnitude and opposite in sign to a corresponding equivalent circuit inductance value of the other transformer.

Knocking detecting unit for internal combustion engine

Abstract: PURPOSE:To make it possible to detect weak knocking, by providing plural filters to detect knocking and by detecting the level of a vibration noise itself and by switching filters so that the characteristic may match to the filter region. CONSTITUTION:The reference angle position of the crankshaft of an engine is detected by angle position detector 1 and is shaped in 2. The base lead angle set previously is operated according to the state of the engine by base lead angle operating circuit 3, and an ignition time is determined in ignition lead angle operating circuit 4 on the basis of the output of operating circuit 3 and the output of correction lead angle operating circuit 5. The output signal of operating circuit 4 is supplied or cut off to the ignition coil by known igniter 6. Though the knocking phenomenon of the engine is detected by knocking detector 7, the characteristic of plural frequency bands is given to filter circuit 8 where this signal is input, and knocking is decided by knocking detecting circuit 9. At this time, the filter characteristic of filter circuit 8 is switched by filter control circuit 11.

TV Interface RF modulation circuitry

Abstract: An interface circuit for selectively generating TV RF signals on one of two adjacent TV channels is designed with two independent RF oscillator-modulator circuits. The respective double sideband modulated signals generated by the RF modulators are respectively passed through separate frequency rejection filters designed to attenuate the lower sound sideband of each of the modulated signals. The resultant signals are applied to a common bandpass filter via an isolation network. The pass band of the bandpass filter encompasses substantially the combination of the pass bands of the broadcast TV channels corresponding to the RF signals generated. Consequently the lower frequency RF modulated signal is similar to a conventional vestigal sideband TV signal and the higher frequency RF modulated signal is a double sideband signal minus the lower sound sideband. The isolation network provides electrical connection between the rejection filters and the bandpass filter but establishes a relatively constant impedance at the respective filter output and input terminals irrespective of changes in the filter impedances so that the filters may be tuned to the desired resonances without interaction between respective filter circuits.

2-D digital filters using logarithmic number systems

Abstract: The letter deals with the design of 2-D digital filters to be implemented in a logarithmic number system. The accuracy of the coefficient representation is considered, and a limit on the maximum useful word length is derived. An optimisation procedure is proposed, together with a few examples of 2-D filter design.

Combined switched-capacitor FIR N-path filter using only grounded capacitors

Abstract: A simple technique is presented that allows the unwanted sidebands of an N-path filter to be suppressed. The circuit realising this technique uses only grounded capacitors.

Electrical filter circuit for processing analog sampling signals

Abstract: An electrical filter circuit for processing analog sampling signals consists of N+1 capacitors interconnected to cyclically circulate N signal charges, the capacitors all being of approximately the same size, and interconnected with an operational amplifier. A plurality of switches are employed, controlled by a clock signal having N+1 phases. Phase controlled switches supply an input signal to the input of the operational amplifier, and provide an output from the filter circuit.

Capacity type converter

Abstract: PURPOSE:To enable correcting of a non-rectilinearity by means of a simple constitution, by constituting a device such that a pulse width signal for compensation is generated, an adder, a substractor, and a factor device are mounted, and a given computation is made using the pulse width signal for compensation and an output voltage. CONSTITUTION:A pulse width signal PW3 for compensation, having a specified pulse width ts, is obtained at a period T, corresponding to a sum of variable capacitors C1 and C2, via a flip flop FF1, an one shot circuit MM, and a comparator CP. A switch SW1 is driven by the signal W3, and after an output KV0 of a coefficient multiplier KC is set to ON or OFF, it is applied to a filter circuit PCf to output a voltage Vf. The compensation voltage Vf is applied to an adder AD2 and is added to a signal voltage V3, and this causes an output voltage Vc of the adder AD2 to accurately proportion a displacement amount x of a moving electrode 10 without being effected by a stray capacity Cs. The adjustment of a factor K of the factor device KC permits the control of a rectilinear property. This permits the correction of non-rectilinearity by means of a simple constitution.

Bandpass filter circuit

Abstract: A bandpass filter circuit includes first and second resistors connected in series between input and output terminals thereof, an amplifier having a gain of three and its output connected to the output terminal, and an RC circuit network connected between the connection point of the first and second resistors and the input of the amplifier and having bandpass characteristics. The RC circuit network comprises a series combination of a third resistor and a first capacitor connected between the connection point of the first and second resistors and the input of the amplifier, and a parallel combination of a fourth resistor and a second capacitor connected between the input of the amplifier and a common terminal of the filter circuit. The third and fourth resistors have an equal resistance value and the first and second capacitors have an equal capacitance value. As one of the first and second resistors use may be made of a variable resistor to change the quality factor, and the third and fourth resistors may be variable resistors ganged with each other to change the center frequency of the passband.

Sensitivity and high-frequency performance of new wave active filters

Abstract: Wave active filters with reduced numbers of operational amplifiers are studied with regard to their sensitivity and the operation at high frequencies. An effective method of compensation for the effect of the finite gain/bandwidth product of the operational amplifiers is suggested and applied successfully. Finally, a ‘lossy’ and a ‘lossless’ WAF realising the same 6th-order bandpass function are compared with respect to their sensitivity and suitability for high-frequency operation.

Filter device for electric vehicle

Abstract: PURPOSE:To increase the impedance of the natural frequency viewed from the power source side so as not to allow the formation of an oscillation circuit by a method wherein a damping resistor is connected in parallel to the reactor of the second filter connected in parallel to the capacitor on the first filter. CONSTITUTION:The first reactor 2 which consist the first filter device and the first capacitor 3 are provided and, at the same time, the second reactor 8, which consists the second filter device, and the second capacitor 9 are connected in parallel to the first capacitor 3. In addition, a damping resistor 10 is connected in parallel to the second reactor 8. As a result, the damping resistor 10 becomes the damper of the oscillation element on the second filter circuit enabling to constitute a nonoscillation circuit and, moreover, the damping resistor 10 of a small value can be used.

Circuitry for sound wave detectors - has filter circuits for amplifying circuit for electrodes of various widths along side of rod-shaped piezoelectric transducer

Abstract: A piezo-electric transducer and an electronic amplifying circuit are provided for detectors sensing sound conducted through solids, esp for detection of fissures in container walls, eg boilers A transducer (1) is provided for detection of a further frequency range of oscillations The transducer is in the form of a rod with one end designed for setting on the container wall (2) This tranducer (1) has a number of electrodes (5-8) along at least one side They are electrically separated from each other and are of different widths along the longitudinal direction (L) An associated, opposing electrode (9) extends along the opposite side The amplifying circuit for the electrodes (5-8) has filter circuits (25-28) The widths of the electrodes are measured and the max frequencies of the separate filters are matched to each other

Realisation of a switched-capacitor voltage wave pseudobandpass filter

Abstract: This letter presents a novel approach to the realisation of monolithic pseudobandpass filters using NMOS technology. The method is based on the use of sampled analogue signals and is related to the wave digital filter in its design techniques. Results are presented for a prototype pseudobandpass filter which uses the periodicity of a cascaded transmission line microwave filter.

Loaddchange compensating circuit

Abstract: PURPOSE:To suppress fluctuations of an output voltage due to a sudden change in load by detecting a signal that corresponds to fluctuations of the load current of an electric power converter, by supplying the detected signal to a voltage control system and then by varying a control signal predictively. CONSTITUTION:The output of inverter 21 for multiple pulse-width modulation, etc., as an electric power converter is applied to loads 23A and 23B via breakers 22A and 22B and fluctuations of output current IL that may cause the output voltage of inverter 21 to vary are detected by current detecting circuit 31 through current transformer 30. The detected current fluctuations are applied via filter circuit 32 to judging circuit 33 and only predicted output variation is applied to adding circuit 29 connected to phase control circuit 26 through analog gate 34, so that an internally-developed voltage will be brought under predictive compensation control before a transient change in the output voltage of inverter 21 appears. At the point in time when the 1st predetermined time passes from the change point of the load current, this control is finished and from this point in time until the 2nd predetermined time passes, the operation of a compensation control system is suppressed to stabilize the operation.

Integrated circuit operational amplifier for filter circuits - has IGFET structure using high common mode and with power supply noise immunity

Abstract: The operational differential amplifier is employed in the construction of filter circuits in digital telecommunications installations. The object of the proposed modification to an operational amplifier made in IG-FET technology is to improve its common mode signal and power supply noise immunity. It is achieved by an alteration in the technological construction of the integrated circuit. The power supply voltage divider (18,19,20) employs one FET (18) constructed as a depletion type FET operating in a saturated condition, and similar to the drain resistors (3,4,300), instead of as an enrichment type. The proposed construction can be achieved by making the FET in the same process step as the drain resistors on the chip.