Showing papers on "Electronic filter published in 1991"

A large-signal very low-distortion transconductor for high-frequency continuous-time filters

Abstract: A high-frequency large-signal very low-distortion voltage-to-current transducer is presented. The total harmonic distortion (THD), for supply voltages of only +or-2.5 V, is smaller than 0.1% for fully differential input signals up to 2.4 V peak to peak (V/sub pp/). The dynamic range is on the order of 89 dB with the transconductor noise integrated over a bandwidth of 1 MHz. Moreover, this structure presents low sensitivity to transistor mismatches. An operational transconductance amplifier (OTA), based on this transconductor, has been used in an adjustable quality factor 1.8-MHz biquadratic continuous-time filter. The quality factor Q is controlled, from 2 to 50, with a novel current-source configuration. Both the OTA and the filter have been fabricated in a CMOS 3- mu m n-well process. >

Activity monitoring apparatus with configurable filters

Abstract: An activity monitor adapted to be worn on the non-dominant wrist of a subject includes a bimorphous beam motion sensor. The output signal of the sensor is amplified in an amplifier circuit having a selectable amplification factor, and filtered by highpass and lowpass filter circuits having individually selectable cut-off frequencies to obtain an analog signal for processing having a bandpass and amplitude characteristic corresponding to a particular body activity under observation. A control and processing circuit within the monitor includes a microprocessor which responds to either resident internal operating instructions or to externally supplied operating instructions, or to designated data signal parameters, to provide configuration control signals to the amplifier and filter circuits, and processing of the collected data, appropriate to the particular activity being monitored. The processed data is digitally stored in an internal memory for subsequent transfer through a data port to an associated computer for display or further processing.

Sigma delta modulator

Abstract: A separate filter circuit is inserted between the D/A converter and the summing junction in the feedback path of a conventional sigma delta modulator. This additional filter allows control of the quantization noise transfer function profile independently of the forward signal transfer function. By proper tailoring of the transfer functions a third or higher order modulator can be constructed without instability developing. The modulator can also be constructed as a completely digital circuit and used as a noise shaping circuit in a digital digital-to-analog converter.

Performance of a narrow band microwave filter implemented in thin‐film YBa2Cu3O7−δ with ohmic contacts

Abstract: Using in situ deposited thin‐film Y1Ba2Cu3O7−δ on LaAlO3 substrates, we have developed a pseudo‐interdigital three‐pole stripline filter with a minimum passband loss under 3.5 dB at 9.5 GHz and 77 K. The passband is very narrow, having a bandwidth of only 50 MHz (0.5%). The filter occupies a volume of less than 0.1 cm3. An equivalent copper filter produced a loss of 18.5 and 28 dB at 77 and 300 K, respectively. The input and output coupling is achieved by ex situ sputtered Au thin‐film contacts defined on the Y1Ba2Cu3O7−δ by a lift‐off technology and ultrasonically bonded to hermetic K connectors. Some of the major concerns in the realization of narrow band filters such as air gaps between high dielectric constant substrates and uniformity of the substrate’s dielectric constant are addressed.

A new combined system of series active and shunt passive filters aiming at harmonic compensation for large capacity thyristor converters

Abstract: A novel combined system of a series active and shunt passive filter is proposed. This system, in which the required rating of the series active filter is only 0.4% as compared with the capacity of a harmonic-producing load, can suppress harmonics in power systems. Compensation characteristics are investigated in detail, and it is clarified theoretically that the compensation characteristics are equivalent to those of the already proposed combined system. Excellent practicability and validity in connection with compensating for harmonics produced by large-capacity thyristor power converters are verified experimentally. >

Realization of current-mode transfer function using second-generation current conveyors

Abstract: This paper proposes an entirely new method for performing current-mode analogue signal filtering Along with adjoint block diagrams, second-generation current conveyor-based (CCII-based) voltage-amplifier filter circuits can be converted to equivalent CCII-based current-amplifier filter circuits with identical sensitivity properties This new transformation method may also be suitable for some OTA-based circuits

A general class of current amplifier-based biquadratic filter circuits

Abstract: A general class of current amplifier-based biquadratic filter circuits is presented which is capable of realizing arbitrary filter functions including the lowpass, highpass, and the bandpass transfer function. These realizations are derived from a class of well-known low sensitivity single amplifier biquadratic (SAB) filter circuits using the principle of adjoint networks. The salient features of the proposed current amplifier filter circuits are that they are synthesized using the same procedure circuits as their op-amp based SAB circuit counterparts, and furthermore, possess the same sensitivities to component variations as the original SAB circuits. >

Glitch remover circuit for transmission links

Abstract: Glitch remover circuit for removing glitches and spikes from control signals received on a SCSI bus line that is coupled from a transmission line includes an input buffer circuit (12) and a filter circuit (14). The input buffer circuit is of a Schmitt trigger type having a transfer characteristic with hysteresis. The input buffer circuit (12) is responsive to control signals received at its input for removing noise spikes around the threshold point of its input on both the rising and falling edges of the control signals so as to provide a pulsed output voltage. The filter circuit (14) is responsive to the pulsed output voltage for generating a filtered pulsed signal at an output terminal only when the pulsed output voltage has a pulse width which is longer than a predetermined time. The filter circuit includes a delay means (28), a gating means (30) and inverter means (32).

Uninterruptible power supply having improved battery charger

Abstract: An UPS apparatus with a back-up battery and successively coupled rectifier, inverter and output filter circuits, having an improved battery charging circuit. The charging circuit has a transformer with its primary winding being part of the output filter, and its secondary winding driving a second rectifier circuit which produces the charging current. The charging circuit contains an impedance preferably connected between the transformer secondary winding and the second rectifier circuit, for capturing only a high frequency portion of the signal from the inverter stage, thereby enabling the utilization of smaller charger circuit elements.

Design strategy for the combined system of shunt passive and series active filters

Abstract: A design strategy for the combined power filter for a three-phase twelve-pulse thyristor rectifier is proposed. The shunt passive filter, which can minimize the output voltage of the series active filter, is designed and tested in a prototype model. A specially designed shunt passive filter makes it possible to reduce the required rating of the series active filter to 60% compared with a conventional shunt passive filter. >

Synthesizing switched-current filters by transposing the SFG of switched-capacitor filter circuits

Abstract: A general synthesis method for switched-current (SI) filter circuits is presented. The SI filter circuit is obtained from the transpose of the signal-flow-graph (SFG) representation of a switched-capacitor (SC) filter realization. The resulting SI circuits realized the same transfer function as the SC filter circuit and, in addition, possess identical component sensitivities. Since the operation of SFG transposition is sensitivity preserving, application of the proposed method to low-sensitivity SC filter circuits will produce low-sensitivity SI filter circuits. >

Distributed Bragg reflector active optical filters

Abstract: The characteristics of active optical filters based on distributed Bragg reflector (DBR) laser diodes are described. The authors present a theoretical model for the small and large signal filter response which can be used to optimize the filter design and operating point. The large signal filter response is dominated by a variety of nonlinear effects, including a wavelength domain bistability. The authors describe a series of experiments in which the predicted filter characteristics are demonstrated. The authors present detailed measurements of the filter transfer function in both transmission and reflection modes under low and high power injection. For the small signal measurements a powerful technique which uses the swept frequency concept is presented. For the large signal regime, measurements of both frequency pulling and wavelength domain bistability are presented. >

Analysis and design of an unusual unity-power-factor rectifier

Abstract: A unity-power-factor rectifier that has a parallel-resonant tank tuned to the second harmonic of the line frequency is analyzed for two filter configurations. A unidirectional-power-flow version of the current-sourced rectifier can operate stably open loop or can be current limited down to zero output voltage. The large inductor normally required is an outstanding disadvantage which can be partially overcome using a resonant filter. The design-oriented analysis includes variable-frequency operation and key component ratings. A design procedure is suggested, and complete experimental verification is obtained using a 120 V, 500 W. 60 Hz rectifier switching at 50 kHz. >

Optical disk apparatus

Abstract: An optical disk apparatus equipped with an objective lens for converging light from a light source onto a track formed on an optical disk, the objective lens being arranged to be movable and an error detecting section for detecting a difference in position between the light converged by the objective lens and the track on the optical disk. Included in the servo section of the optical disk apparatus are an amplifier for amplifying an output of the error detecting section with an amplification factor which is variable and a filter circuit for cutting off a frequency component of an output of the amplifying means, the cutoff frequency being variable. On the basis of the output of the filter circuit, a moving device moves the objective lens so that the difference between the converged light and said track is reduced. The amplification factor of the amplifier and the cutoff frequency of the filter circuit are determined in correspondence with the position of the objective lens. These amplification factor and cutoff frequency are prestored in a memory so that the corresponding amplification factor and cutoff frequency are read out therefrom in accordance with the current position of the objective lens.

Digital filter circuit

Abstract: When each sample is expressed by digital signals of 8 bits, 8 bits constituting each of the digital signals are divided into data of upper 5 bits including the most significant bit, and data of lower 4 bits including the least significant bit. These two data are respectively inputted to two filter circuit units, and are simultaneously subjected to a filtering process separately. Outputs of these two filter circuit units are inputted to an adder. In the adder, the output of the filter circuit unit being data of upper 5 bits subjected to a filtering process is weighted by a factor of 2 to the 4th power, and the weighted output is added to the output of the other filter circuit unit. The results of adding are outputted from the adder as signals obtained by the original digital signals of 8 bits subjected to the filtering process. Since the number of bits of individual data is made small by the division, the operation speed of computing elements and the number of times of recursive or multiple uses of computing elements are increased so that the circuit scale of the entire filter circuit can be reduced.

System and circuit architecture for echo cancellation and a television receiver comprising same

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

Sigma-delta modulator

Abstract: 1-Bit signma-delta modulator having a loop filter (5,6,8), a first negative feedback loop (13,7,8) and a second negative feedback loop (14,4,5,6,8). The filter sections 5 and 8 are passive filter elements and filter section 6 is a high-gain active filter element. A circuit of this type makes a very high clock rate possible in the decision switch 10.

Novel CMOS linear OTA using feedback control on common source node

Abstract: Time continuous filter circuits using OTA-C or MOSFET-C structures are being reported frequently for various applications. The main issue is dynamic range because of the confined signal level handling capability of the basic differential pair. A linear OTA is presented using the MOS transistor square law characteristic.

High-decimation digital filters

Abstract: The architecture of an efficient high-decimation rate filter is presented. A high-decimation rate filter can extract narrowband signal intelligence from a wideband signal. As a result, it is important to many signal processing applications found in communications and instrumentation. The presented high-decimation rate filter is a multi-rate system consisting of a cascaded integrator-comb (CIC) section and a finite impulse response (FIR) filter. The function of the CIC section is to perform efficient high-decimation filtering over the entire frequency band. The function of the FIR filter is to achieve prespecified transition band performance at baseband. The authors investigate the CMOS implementation of a 33 MHz high-decimation rate filter, its hardware implementation, and its performance. Examples of its use are also provided. >

Band-stop filter circuit suitably made into monolithic microwave integrated circuits

Abstract: An image band-stop filter circuit includes a transmission line formed on a substrate of GaAs and a T circuit connected in parallel to the transmission line and having a high pass filter characteristic. The T circuit includes series-connected first and second capacitances connected in parallel to the transmission line and a stub having one end connected to a node between the first and second capacitances and the other end short-circuited. The stub has a line length which becomes inductive in an image signal band to be removed. As a result, the lengths of the transmission line and the stub can be reduced to enable the band-stop filter circuit to be made into a MMIC with ease while achieving an excellent signal transmission characteristic.

All-digital implementation of the carrier recovery loop in digital radio systems

Abstract: The authors address the issue of complete digitization of the carrier recovery loop in digital microwave radio systems. First, they present digital equivalents of conventional carrier recovery loops employing either a passive filter or an active filter with a high gain. Next, they address the issue of extending the acquisition range of these loops, which is a critical problem in digital radio receiver design. For carrier recovery loops with the digital equivalent of an active loop filter, the loop acquisition range was investigated using two previously proposed PFDs (phase and frequency detectors). With the best of these two detectors, it was shown that the acquisition range can be very close to 1/8 T, which constitutes a fundamental limit for decision-feedback carrier recovery loops with symbol-rate phase error measurements. >

The Combined System of Series Active and Shunt Passive Filters

Abstract: This paper describes a simple and clear approach to analyze harmonic instability of phase controlled thyristor converters with input passive filters. It is shown by analysis and experiment that harmonic instability may occur at the parallel resonant frequency between the passive filter and the ac source even if the ac source impedance is low.A combined system of series active and shunt passive filters has already been proposed as a new approach to harmonic compensation in power systems by the authors. It is confirmed analytically and experimentally that the series active filter used has the capability to suppress the harmonic instability at the parallel resonant frequency. However, it is also shown that the series active filter may cause harmonic instability adversely at lower frequencies. However, harmonic instability at a frequency except for the parallel resonant frequency does not cause any practical problem. The obtained analytical results are confirmed by experiment in detail.

Universal electronic ballast system

Abstract: A universal electronic ballast system (10) is provided for actuating at least one gas discharge lamp (1900) having any one of a plurality of predetermined wattage ratings. Electronic ballast system (10) includes a filter circuit coupled to an AC power mains (100, 110) for substantially suppressing spurious signals passing into or from the power source. The filter circuit is coupled to a regulated switching power supply circuit (14) which generates a regulated boost voltage and draws a substantially constant in phase sinusoidal load current from the power source supplied to a switching circuit (16) which generates a regulated pulsating current at a predetermined frequency. Responsive to the regulated pulsating current a high voltage is induced in the primary windings (1710 and 1680) of induction transformer (T3). The high voltage is coupled to gas discharge lamp (1900) by means of the magnetic coupling betwen primary winding (1730) and secondary winding (1765) of the output transformer (T2). Universal electronic ballast system (10) monitors the presence of gas discharge lamp (1900) by means of the voltage divider (1270, 1830) and protection circuit formed by diode (1490), and transistors (1380 and 1440), for maintaining the switching transistor (1590) in an "off" condition by shunting the base drive signal therefrom responsive to gas discharge lamp (1900) being removed from ballast system (10).

Compact coupled line filter circuit

Abstract: A filter circuit includes a first pair of RF propagation networks disposed to provide a first coupled line section having a first electrical pathlength at a first frequency, means for providing a signal path between an input port of the filter and the first coupled line section and a second pair of RF propagation networks disposed to provide a second coupled line section having a second different electrical pathlength at the first frequency with a first one of the first pair of RF propagation networks coupled to a first one of the second pair of RF propagation network The filter circuit further includes a third pair of RF propagation networks disposed to provide a third coupled line section having a third different electrical pathlength at the first frequency with a second one of the second pair of RF propagation networks coupled to a first one of the third pair of RF propagation networks and means for providing a signal path between the third coupled line section and an output port of the filter

Oil filter, especially for tap changes of step-down transformers

Abstract: The invention relates to an oil filter, especially for tap changers of tapped transformers, as a component of a separate filter circuit, the oil filter having two concentrically arranged filter chambers. In this case, the outer filter chamber is used for filtering out solid impurities and the inner filter chamber, in which, if required, guide elements are arranged in the form of a labyrinth, is filled with moisture-absorbing material and is used for extraction of the water that is in the oil.

Multidielectric microstrip filter

Abstract: A multidielectric electrical filter is adapted for passing a primary electrical signal at a first frequency while attenuating higher frequency signals, most notably harmonic spurs. The filter comprises an elongated transmission line and one or more radial pads overlying a first surface of a dielectric support opposite a ground plate. The support is formed of a first dielectric material to achieve a desired capacitive coupling between the pad and the ground plate effective to attenuate the higher frequency signals. The support further comprises a region underlying the transmission line and containing a second dielectric material having a dielectric constant distinct from the first material. Preferably, the region includes one or more slots containing air to minimize the capacitive coupling between the transmisison line and the ground plate and thereby reduce insertion loss of the primary signal that would otherwise lessen the power of the signal to the antenna.

Digital power amplifier

Abstract: In a digital power amplifier, a high frequency linear modulated driving signal is used to control a bridge circuit arrangement of transistors. By inputting this high frequency linear modulated signal to a bridge arrangement of driving comparators, a controlled dead band is created and a balanced output is obtained from the bridge circuit arrangement of transistors. The balanced output signal is then fed through a filter circuit for demodulation. An alternative embodiment of the invention employs a bridge circuit consisting of transistors connected in parallel for improved power handling capabilities.

Transmission interface circuit for lan

Abstract: PURPOSE: To reduce the packaging area of a filter circuit portion and to reduce the cost by halving the number of components without damaging the transmission characteristic. CONSTITUTION: A driver IC 1 and an unbalanced filter circuit 10 are combined and connected to a twisted pair electric wires 12 through a pulse transformer T 1 at a transmission side. The unbalanced filter circuit 10 consists of two stages of LC filter sections 14, 15 each composed of a coil and a capacitor and the LC filter is inserted into both signal lines 16, 17. A receiver IC 2 and an unbalanced filter circuit 20 the same as the transmission side are combined and connected to a twisted pair electric wires 12 through a pulse transformer T 2 at a reception side. COPYRIGHT: (C)1992,JPO&Japio

SAW filters and competitive technologies: a comparative review

Abstract: The current performance capabilities of surface acoustic wave (SAW) bandpass filters are reviewed and summarized for the frequency range of 30 MHz to 3 GHz. SAW coupled-resonators with up to 0.8% bandwidth, low loss transversal, and surface-skimming bulk-wave filters are included. SAW filter capabilities are compared with those of competing bandpass filter technologies in the same frequency range. These include bulk crystal, LC, cavity, helical, tubular, dielectric resonator, combline, interdigital, and stripline technologies. The following two needs are addressed: (1) SAW filter designers and marketers must be informed about the current capabilities of competing technologies, and (2) RF system designers need reference material to aid the efficient selection of optimum filters. Such reference literature is scarce and is often incomplete or obsolete. >

Oversampling filter circuit

Abstract: PURPOSE:To make it possible to enhance the oversampling processing speed by making the operating speed of each adder, multiplier, and so on constituting the digital filter circuit equal to input data speed CONSTITUTION:A sample number converting circuit 1 in the over-sampling circuit carries out sample number conversion on input data, while the interpolation points that is obtained by the sample number conversion processing are provided with temporary reference value 0 Further, the data processing section at the even side of the digital filter circuit and the data processing section at the odd side thereof carry out the convolution arithmetic operation on each data obtained from a circuit 1, the DC correction is carried out on resulatant data using the correcting value corresponding to the essential reference value, and the output from the data processing section at the even side and the output from the data processing section at the odd side are alternately selected and output With this constitution, the operation speed of each adder and multiplier in the data processing section at the even side and the operation speed of each adder and multiplier in the data processing section at the odd side are made equal to the input data speed, thereby carrying out the oversampling processing at doubled high speed