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Showing papers on "RC circuit published in 1978"


Journal ArticleDOI
TL;DR: In this article, a unified view of sampled-data charge-conserving circuits for analog-to-digital (A/D) and digital-toanalog (D/A) converters and audio frequency filters is presented.
Abstract: Precision analog integrated circuits may be realized using MOS transistors and accurately ratioed MOS capacitors. Compatibility with high-density digital MOS circuits leads to the possibility of fully Integrated subsystems employing both analog and digital circuitry. This paper presents a unified view of sampled-data charge-conserving circuits for analog-to-digital (A/D) and digital-to-analog (D/A) converters and audio frequency filters.

76 citations


Journal ArticleDOI
TL;DR: In this article, a review of active R filters is presented, where the authors discuss nonideal aspects and limitations of the active R filter performance, in particular, the potentially severe effect of temperature-induced drift in the amplifier's dynamic response is considered, and methods of drift compensation are discussed.
Abstract: Active filters that derive their frequency response from internal amplifier dynamics, but use no external capacitors in their implementation, are referred to as “active R” filters. Because of their potential advantages in terms of miniaturisation (i.e. fabrication), ease of design and high-frequency performance, these circuits are receiving increasing attention in the technical literature. The paper reviews the published synthesis procedures for 1st-, 2nd- and higher-order active R filters; it is shown that the 1st- and 2nd-order circuits developed to date are special cases of a general active R topology. The paper discusses nonideal aspects and limitations of active R filter performance, which arc usually neglected in the literature; in particular, the potentially severe effect of temperature-induced drift in the amplifier's dynamic response is considered, and methods of drift compensation are discussed. Experimental results are presented to verify filter performance and the theoretical derivations

68 citations


Journal ArticleDOI
A.M. Soliman1
01 Nov 1978
TL;DR: In this article, a canonic active RC circuit for realizing an ideal grounded inductor using a single second generation current conveyor as the active building block is described, which may be considered as a novel active-gyrator circuit realized using only a single current conveying device.
Abstract: A new canonic active RC circuit for realizing an ideal grounded inductor using a single second generation current conveyor as the active building block is described. The circuit may be considered as a novel active-gyrator circuit realized using only a single current conveyor.

61 citations


Patent
08 Sep 1978
TL;DR: In this article, an electrical device for protecting an alternating current network in which a static inverse time-overcurrent relay obtains network current information and relay circuit operating power from a current transformer having two secondary windings is presented.
Abstract: An electrical device for protecting an alternating current network in which a static inverse time-overcurrent relay obtains network current information and relay circuit operating power from a current transformer having two secondary windings. Low transformer burden and accurate network information signals that are linearly responsive to a wide range of network current magnitudes are achieved through the use of a switching circuit that prevents the simultaneous operation of both secondary windings. The relay circuit employs an RC network with a short, precision time constant for curve shaping and employs digital counting techniques to provide time delay multiplication, precision time scale selection and a variable delay time variable in accordance with the magnitude of system current.

39 citations


Patent
11 Jul 1978
TL;DR: In this paper, an electronic AC electric energy measuring circuit converts a di/dt analog input signal into a pulse width modulated signal responsive to the amplitude of a current component of an alternating current energy quantity to be measured.
Abstract: An electronic AC electric energy measuring circuit converts a di/dt analog input signal into a pulse width modulated signal responsive to the amplitude of a current component of an alternating current energy quantity to be measured. The pulse width modulated signal is produced by a first modulator circuit including an integrator circuit deriving both a modulating frequency signal and a current analog signal proportional to the current component. A multiplying circuit receives a voltage analog input signal and applies it to a reference input of a second modulator circuit. The modulating control of the second modulator circuit receives the pulse width modulated signal so that the multiplying circuit produces a variable amplitude and pulse width modulated signal having an average value equal to an average power measurement. An analog to frequency converter including a second integrator circuit receives the output of the multiplying circuit to produce an output pulse representative of a quantized amount of electric energy.

35 citations


Journal ArticleDOI
TL;DR: In this paper, a general procedure for the design of an active switched-capacitor filter from an actlve-RC model is given, based on trapezoidal integration, and the resulting sampled-data circuit response is related to that of the model through bilinear z-transformation.
Abstract: A general procedure is given for the design of an active switched-capacitor filter from an actlve-RC model. The process is based on trapezoidal integration. The resulting sampled-data circuit response is related to that of the model through the bilinear z-transformation.

35 citations


Journal ArticleDOI
TL;DR: In this paper, a systematic procedure for the design of active filters obtained as operational simulations of LC ladder prototypes is presented, based on the signal-flow graph (SFG) approach, but allowing one to obtain the final circuit without ever considering signal flow graphs.
Abstract: A systematic procedure is presented for the design of active filters obtained as operational simulations of LC ladder prototypes. The method is based on the signal-flow graph (SFG) approach, but allows one to obtain the final circuit without ever considering signal-flow graphs. Practical design problems, namely, scaling for maximum dynamic range, stabilizing the reciprocator amplifiers, predistorting the LC prototype to compensate for the parasitic reactances introduced by reciprocators, eliminating the inherent dc offsets, and tuning are solved and illustrated by examples. Complete design and experimental results are given for a twelfth-order bandpass channel bank filter.

34 citations


Patent
05 Jun 1978
TL;DR: In this paper, an energy storage RC network holds the UVR solenoid in for momentary drops in system voltage by using DC control voltage derived from the system voltage to activate a first relay to apply the control voltage across a dropping resistor and an undervoltage release (UVR) soloenoid.
Abstract: DC control voltage derived from the system voltage activates a first relay to apply the control voltage across a dropping resistor and an undervoltage release (UVR) solenoid, thereby holding the UVR solenoid in while the system voltage remains above a minimum level An energy storage RC network holds the UVR solenoid in for momentary drops in system voltage In the event of a protracted system undervoltage condition, the first relay drops out to drop out the UVR solenoid and trip a system circuit breaker When nominal system voltage is restored, the control voltage activates the first relay and, via an RC charging circuit, temporarily actuates a second relay to switch out the dropping resistor, thereby temporarily applying full control voltage across the UVR solenoid to reset it

26 citations


Journal ArticleDOI
TL;DR: A protective network for silicon-gate C-MOS/SOS arrays has been designed that is capable of protecting input circuits from static discharges in excess of 2200 V, and exceeds the requirements without degrading circuit speed.
Abstract: A protective network for silicon-gate C-MOS/SOS arrays has been designed that is capable of protecting input circuits from static discharges in excess of 2200 V. This paper describes the results of a program undertaken at RCA to develop a protection network for C-MOS arrays on sapphire substrates capable of withstanding 1500-v static discharges. A test chip with eight input protection configurations was designed, processed, and tested. The results were incorporated into a network design that exceeds the requirements without degrading circuit speed.

25 citations


Journal ArticleDOI
TL;DR: In this paper, a general theory for extended bandwidth operation of actively compensated finite gain amplifiers is developed for RC active filters and applications in inductance simulation schemes, and three new circuits are given which implement the theory.
Abstract: A general theory is developed for extended bandwidth operation of actively compensated finite gain amplifiers. Designs for three new circuits are given which implement the theory. These circuits employ only operational amplifiers and resistors and their gains depend only on their resistor ratios. Thus they are suitable for IC fabrication. Further in IC technology, the characteristics of the operational amplifiers as well as the resistor ratios track closely with each other with reference to temperature and aging. Thus the extended bandwidth operation of the amplifiers will be available over a wide temperature range as well as under varying aging conditions. Their characteristics can be tuned easily by trimming only two resistors. Applications of the new amplifiers have been considered in RC active filters as well as in inductance simulation schemes. Experimental results are given which closely agree with theoretical predictions. The results also indicate that substantial improvement in the usable bandwidth of the circuits employing the new amplifiers may be expected over those using the conventional design of finite gain amplifiers.

24 citations


Journal ArticleDOI
TL;DR: Measurements on a commercial helical-scan video transport indicate that the harmful effects of a dc null can be greatly reduced; specifically the error rate on a 1023-bit 20-Mbit/sec pseudorandom pattern was reduced from 3 × 10-5to below 10-8.
Abstract: The dc null in a digital magnetic recording channel is equalized in a novel way which allows recovery of direct recorded NRZ waveforms with no coding constraints. The technique involves decision feedback equalization which can be implemented with simple RC filters. Feedback power is determined by the choice of RC and can be optimized independently of the fact of equalization. Measurements on a commercial helical-scan video transport indicate that the harmful effects of a dc null can be greatly reduced; specifically the error rate (excluding dropouts) on a 1023-bit 20-Mbit/sec pseudorandom pattern was reduced from 3 × 10-5to below 10-8.

Journal ArticleDOI
01 Jul 1978
TL;DR: Two new canonic active RC networks are proposed for the simulation of grounded and floating lossy inductors, which combine an operational amplifier, four resistors, and one grounded capacitor.
Abstract: Two new canonic active RC networks are proposed for the simulation of grounded and floating lossy inductors. A grounded inductor is simulated with one operational amplifier, four resistors and one grounded capacitor. The circuit for a floating inductor employs two amplifiers, six resistors, and only one capacitor.

Patent
18 Sep 1978
TL;DR: In this paper, an overload detecting circuit for a PWM amplifier includes an output current detecting circuit and an output voltage detecting circuit, and a comparison circuit is provided to produce an overload indicative signal in response to the comparison result between the outputs of the rectifying circuit and of the output current detector.
Abstract: An overload detecting circuit for a PWM amplifier includes an output current detecting circuit and an output voltage detecting circuit. The output of the output voltage detecting circuit is supplied to a rectifying circuit having a discharge time constant determined by the cut-off frequency of a low pass filter as a demodulator of the PWM amplifier. A comparison circuit is provided to produce an overload indicative signal in response to the comparison result between the outputs of the rectifying circuit and of the output current detecting circuit.

Patent
13 Nov 1978
TL;DR: In this paper, a frequency converting circuit is provided comprising a constant current source, an oscillation circuit including an amplifier, an operation circuit and a frequency converter for converting the output signal of the operation circuit.
Abstract: A frequency converting circuit is provided comprising a constant current source, an oscillation circuit including an amplifier so connected to the constant current source as to operate in the unsaturated operation region owing to the output current of the constant current source, an operation circuit which receives an input signal and the output signal from the oscillation circuit and produces an output signal corresponding to the product of both the received signals and a frequency converter for converting the frequency of the output signal of the operation circuit.

Patent
Marvin A. Glazer1
16 Nov 1978
TL;DR: In this article, a temperature sensor circuit is described, which employs a plurality of semiconductor junctions arranged either in a current-mirror configuration using a bias circuit and current source transistors or in a bridge configuration in order to provide a differential output voltage which is linearly proportional to temperature.
Abstract: A temperature sensor circuit is disclosed which employs a plurality of semiconductor junctions arranged either in a current-mirror configuration using a bias circuit and current source transistors or in a bridge configuration in order to provide a differential output voltage which is linearly proportional to temperature. The temperature sensor circuit is ideally suited for fabrication as an integrated circuit, and the differential output voltage is relatively insensitive to integrated circuit processing variations as well as power supply variations. By providing a differential output signal, the circuit is particularly useful in high noise environments such as automotive applications.

Journal ArticleDOI
TL;DR: A solution to the problem of realising the bilinear transformation in a switched capacitor network with experimental verification is given, presented in the context of an active integrator, but is quite general.
Abstract: Recently, a new technique for filtering in MOS LSI using switched capacitors has been demonstrated (see ibid., vol.SC-12, p.592, 1977). Basically, the technique involves the replacement of resistors, in continuous active RC filter designs, with an analogous circuit using switches and capacitors in a sampled-analog equivalent. The approach creates a problem, however, in that the switched capacitor structures do not directly simulate the equivalent resistors over the useful frequency range. This leads to the necessity for Z-transform analysis, and causes the sampled analog circuit behavior to degrade from the simplicity of the continuous active equivalent. A solution to the problem of realising the bilinear transformation in a switched capacitor network with experimental verification is given. The solution is presented in the context of an active integrator, but is quite general.

Patent
23 Jan 1978
TL;DR: In this article, a detection circuit is proposed to accurately monitor an AC signal, which is modulated by information characteristic or indicative of the integrity of a conveyor belt or the like, to provide a distinguishable output representative of such integrity.
Abstract: A detection circuit accurately monitors an AC signal, which is pulse modulated by information characteristic or indicative of the integrity of a conveyor belt or the like, to provide a distinguishable output representative of such integrity. Such distinguishable output may be utilized for display purposes and/or for control purposes to stop a ripped conveyor belt. The detection circuit includes a combination circuit of a voltage doubler with high pass filters utilizing full wave rectifiers, RC filters, and a common summing junction. The detection circuit also includes a DC level detector with an automatic gain response adjustment.

Journal ArticleDOI
TL;DR: In this article, a new active RC circuit is proposed for the realisation of lossless floating inductance employing three operational amplifiers as unity-gain summers, three external resistors and a single grounded capacitor.
Abstract: A new active RC circuit is proposed for the realisation of lossless floating inductance employing three operational amplifiers as unity-gain summers, three external resistors and a single grounded capacitor. Unlike other existing three-amplifier and two-amplifier circuits for lossless floating inductance, the new circuit realises an inductance that is controllable through a single resistor.

PatentDOI
TL;DR: In this article, a muting circuit for loudspeakers is proposed, which includes an around zero-volt detection circuit for detecting around the zero volt level of a commercial AC voltage, and a threshold circuit is connected to the RC time constant circuit and operates a loudspeaker relay when the charge on the capacitor either exceeds or decreases below a predetermined level.
Abstract: A muting circuit for loudspeakers is operable to disconnect a loudspeaker from an amplifier immediately upon a power supply being interrupted. The muting circuit includes an around-zero-volt detection circuit for detecting around the zero volt level of a commercial AC voltage. An RC time constant circuit is controlled by the output of the around-zero-volt detection circuit to either charge or discharge the capacitor in the RC time constant circuit only when the around zero volt level is detected. A threshold circuit is connected to the RC time constant circuit and operates a loudspeaker relay when the charge on the capacitor either exceeds or decreases below a predetermined level.

Patent
24 May 1978
TL;DR: In this paper, a pressure detecting apparatus consisting of a bridge circuit with semiconductor pressure elements, a constant voltage circuit for applying voltage to the bridge circuit, and an amplifier circuit for amplifying the output of the bridge circuits to provide an electrical signal proportional to the pressure variation is presented.
Abstract: A pressure detecting apparatus which comprises a bridge circuit with semiconductor pressure elements; a constant voltage circuit for applying voltage to the bridge circuit; an amplifier circuit for amplifying the output of the bridge circuit thereby to provide an electrical signal proportional to the pressure variation; and a voltage correcting circuit connected between the input of the amplifier circuit and the input of the bridge circuit for amplifying the output of the bridge circuit to feed it back to the bridge circuit, and in which the output of the voltage correcting circuit and the output of the constant voltage circuit are applied to the bridge circuit to improve the linearity of the response characteristic or the pressure-electrical signal output characteristic.

Patent
08 Mar 1978
TL;DR: In this paper, a tunable UHF transistor oscillator with a frequency determining resonating LC circuit reduction of the harmonic to fundamental ratio is obtained through the use of an output circuit consisting of output resistor connected in parallel with a resistor voltage divider a part of which is used as a damping resistor for a second controllable tuned circuit.
Abstract: In a tunable UHF transistor oscillator with a frequency determining resonating LC circuit reduction of the harmonic to fundamental ratio is obtained through the use of an output circuit consisting of an output resistor connected in parallel with a resistor voltage divider a part of which is used as a damping resistor for a second controllable tuned circuit comprising an inductor with a larger inductance than that of the frequency determining circuit and the same capacitance and a non linear circuit between the control voltage source and the adjustable capacitor of said second circuit. The output is taken across the second tuned circuit. Coupling between the transistor and the frequency determining circuit is low.

Journal ArticleDOI
TL;DR: In this paper, the conditions for natural mode oscillations for a class of active RC circuit configurations are analyzed and realizability conditions for a number of configurations are derived showing independent control of the condition of oscillation mid frequency tuning by means of single elements.
Abstract: The conditions for natural mode oscillations for a class of active RC circuit configurations are analysed. Realizability conditions for a number of configurations are derived showing Independent control of the condition of oscillation mid frequency tuning by means of single elements. In addition, low frequency generation is possible without requiring large values of RC elements. The circuits, therefore, are suitable for adoption to HIC techniques, in which event the stability of oscillation frequency would also improve

Journal ArticleDOI
TL;DR: In this paper, the authors proposed a logarithmic RC converter-digitizer based on time measurements of the exponential voltage decay across a linear RC network, and the linearity error of this converter, built with commonly available and noncritical components, was found to be less than 0.05 percent of full scale for a two-decade operation.
Abstract: Theoretical considerations and experimental data support the suggestion that high accuracy of conversion and long-term stability could be obtained with a logarithmic RC converter-digitizer. The operation of the proposed converter is based on time measurements of the exponential voltage decay across a linear RC network. Linearity error of this converter, built with commonly available and noncritical components, was found to be less than 0.05 percent of full scale for a two-decade operation.

Proceedings ArticleDOI
13 Jun 1978
TL;DR: In this article, the root locus method was used to obtain the third-order characteristic equation of the surge voltage across the transistor in a two-winding regulator with two-way reactor.
Abstract: This paper presents the optimum design of an RC snubber to suppress the surge voltage across the transistor in a switching regulator with two-winding reactor. Analyzing the surge voltage across the transistor with an RC snubber by means of high-frequency equivalent circuits, we obtain the third-order characteristic equation. This third-order equation is analyzed by the aid of the root locus method. As a result, the region where the surge voltage can be suppressed is described in the R-C plane. The experimental confirmation of this analysis is shown. Considering the snubber loss, the optimum resistance and capacitance can be obtained. Further, the precise design procedure of RC snubbers is discussed by normalization and numerical calculation. This procedure is summarized in easy-to-use nomographs.

Patent
18 Oct 1978
TL;DR: In this paper, the phase detection method is used for stereophonic signals. The detector provides an output indicating in phase or in opposition conditions for complex signals, i.e. signals having a wide range of frequency and amplitude components.
Abstract: The phase detection method is esp. for stereophonic signals. The detector provides an output indicating in phase or in opposition conditions for complex signals, i.e. signals having a wide range of frequency and amplitude components. The two input channels (C1, C2) are coupled into the circuit by a pair of transformers each having twin secondaries (21, 22, 31, 32) one transformer only having a connection sense reversal switch (1). The secondaries feed two operational amplifiers and integration chains (4-7). One amplifier acts as an addition circuit and the second a subtraction, their outputs being integrated in an RC circuit which includes a detection diode (61, 71). Teh interated outputs are compared in a further resistive feedback operational amplifier (80) with a back to back diode (86) pair input circuit. The comparator output directly feeds an LED pair (90, 91) indicating IN or OPPOSITION phase conditions.

Patent
25 Aug 1978
TL;DR: In this article, a programmable timing circuit has a plurality of outputs with each output supplying a different number of equal width pulses during a predetermined like time period whereby each output corresponds to a different ratio.
Abstract: A narrow-band RC active bandpass filter, in which the center frequency may be changed by changing the resistance values of certain resistive elements, has the certain resistive elements switchably connectable into and out of the RC network so that the ratio of time during which the resistors are connected to the network to the time during which resistors are not connected to the network determines the effective resistance thereof. A programmable timing circuit has a plurality of outputs with each output supplying a different number of equal width pulses during a predetermined like time period whereby each output corresponds to a different ratio. The timing circuit actuates and deactuates the switchable connection from a selected output thus deriving the required effective resistance for a predetermined center frequency. The bandwidth of the passband is set by a different resistive element and remains substantially unchanged as the center frequency is changed by changing the effective resistance of the certain resistive elements.

Journal ArticleDOI
TL;DR: In this paper, generalization schemes and illustrative examples are given for a class of high-Q high-frequency two amplifier active RC networks using all-pass circuits with either positive or negative gain constant.
Abstract: Generalization schemes and illustrative examples are given for a class of high- Q high-frequency two amplifier active RC networks using all-pass circuits with either positive or negative gain constant. In this preliminary study, the \omega_0 and Q degradations of the networks are compared with the state-variable filter. Experimental results for a bandpass filter application are included.

Journal ArticleDOI
TL;DR: In this paper, a single-amplifier single-capacitor circuit simulating a grounded inductor for use in active RC high-pass and band-pass filters is discussed, and a method of compensating for the nonideal behaviour of simulated inductors of this type is presented.
Abstract: A new single-amplifier single-capacitor circuit simulating a grounded inductor, for use in active RC highpass and bandpass filters, is discussed, and a method of compensating for the nonideal behaviour of simulated inductors of this type is presented. In contrast to known compensation methods, the compensation procedure proposed here does not seek to improve the nonideal simulated inductors, but deliberately designs the simulating circuit to have a specific biquadratic impedance function and then modifies the filter circuit so as to produce the required loss/frequency response using these biquadratic impedances instead of the original inductors. For bandpass filters the compensation is only approximate. However, for highpass filters, complete compensation can be achieved over the entire frequency range in which the gain of the amplifier can be adequately described by a single-pole model; the cost of achieving this is some increase in sensitivity. The new design procedure has been applied successfully to a 5th-order Cauer-type highpass filter; computed incremental sensitivities and some measured results are presented.

Patent
16 Jan 1978
TL;DR: In this article, the phase angle during which current flows through the motor in the negative halfwave of the voltage supply is determined by a first thyristor, under control of a speed setting provided in an RC circuit.
Abstract: A first thyristor, under control of a speed setting provided in an RC circuit varies the phase duration of current supply to the motor during positive halfwaves of the a c supply, and a second thyristor controlled in accordance with the motor current provided through the first thyristor determines the phase angle during which current flows through the motor in the negative halfwave of the voltage supply, so as to maintain the speed at the set value under varying conditions of load. During positive halfwaves, a capacitor is charged to a voltage corresponding to the amount of current flow through the motor and during the following negative halfwave, the charge is increased at a rate set by an RC circuit, resulting in turning on the second thyristor early under heavy load conditions, and late under light load conditions, and indeed not at all under idling conditions.

Patent
03 Aug 1978
TL;DR: In this article, an ignition element is provided between the resistor-capacitor circuit capacitor and the switch control electrode and at least one current source circuit is in parallel with the circuit capacitor.
Abstract: The electric motor starting circuit has in the motor circuit a controllable switch with a thyratron characteristic, with a parallel resistor-capacitor circuit. An ignition element is provided between the resistor-capacitor circuit capacitor and the switch control electrode. At least one current source circuit is in parallel with the resistor-capacitor circuit capacitor (C2). It consists of a transistor (T) with an emitter resistor (R2) and a base voltage divider (R3, R4). A capacitor (C1) is in parallel with the resistor (R3) connected to the emitter resistor (R2).