Showing papers on "RC circuit published in 1979"

MOS switched-capacitor filters

Abstract: In the past several years, much progress has been made in bringing the economies of integrated-circuit technology to bear on the realization of voiceband frequency selective filters. This paper will review one approach to this problem, the use of switched-capacitor techniques. The paper emphasizes the practical aspects of switched-capacitor filter design under the constraints imposed by MOS integrated-circuit technology. The basic operation of switched-capacitor filters is reviewed, followed by a discussion of the properties of the various circuit building blocks in MOS technology. Finally, a summary of several filter organizations which appear to be well suited to switched-capacitor implementation is presented.

Calculation of parameter values from node voltage measurements

Abstract: In this paper a theorem is given for the necessary and sufficient test conditions required to determine the value of a circuit component from node voltage measurements at a single test frequency. Several techniques are then presented for the calculation of circuit component values from voltage measurements, including a new technique based on the adjoint circuit concept. In addition, some results are presented on the measurement of component values using different test frequencies.

Optimum Design of RC Snubbers for Switching Regulators

Abstract: The optimum design of an RC snubber to suppress the surge voltage across the transistor in a switching regulator with a two-winding reactor is presented. Analyzing the surge voltage by means of high-frequency equivalent circuits, we obtain the third-order characteristic equation. This third-order equation is first 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. Then considering the snubber loss, the optimum resistance and capacitance can be obtained. Second, the precise design procedure of RC snubbers is discussed by normalization and numerical calculations. This procedure is summarized in easy-to-use nomographs.

Two‐capacitor problem: A more realistic view

Abstract: A popular circuit problem encountered in introductory physics and electromagnetics texts is discussed here in a more realistic manner by considering the self‐inductance of the circuit. For practical values of the circuit parameters, the model usually put forth to solve this problem, a series RC circuit, appears inappropriate.

Active filters with zero amplifier sensitivity

Abstract: A general characterization of second-order active-RC filters employing one, two, and three operational amplifiers is given. When certain conditions are met, it is shown that the desired poles can be rendered insensitive to first- and second-order changes in the time constants of the operational amplifiers. Several novel circuits possessing this zero pole-sensitivity property, as well as zero \omega_0 and Q sensitivity properties, are presented and discussed. Experimental verification of the results and comparisons to other popular second-order active-RC realizations bear out the significantly superior performance of these filters.

Direct drive ballast with starting circuit

Abstract: An electronic ballast circuit includes a direct drive high frequency inverter circuit with a tuned output circuit and a drive circuit dependent upon current flow in a load circuit. The high frequency inverter circuit is coupled to a DC potential source which is derived from a pulsed DC potential source by way of a charge storage and charge isolating circuit. An oscillator provides a starting capability for the high frequency inverter circuit and is essentially removed from the active circuitry upon energization of the high frequency inverter circuit.

Novel active RC circuit for floating-inductor simulation

Abstract: Whereas existing methods of lossy/lossless floating-inductance simulation would require two to four operational amplifiers or current conveyors and compulsorily require exact matching of some components, this contribution presents a novel circuit which employs only a single current conveyor along with only three passive components to realise a floating-inductor (parallel RL), without any component-matching requirement.

Digital phase control circuit with auxiliary circuit

Abstract: A digital phase control circuit which includes a controllable oscillator, a programmable divider coupled to the oscillator, a reference frequency source, a phase discriminator coupled to the outputs of the programmable divider and reference frequency source and means coupling the output of the phase discriminator to a control input of the oscillator. In addition to these components, an auxiliary circuit is provided which has its input coupled to the output of the phase discriminator and first and second outputs coupled to the reference frequency source and the programmable divider. The auxiliary circuit generates a first signal at the input of the reference frequency source when the phase difference between the signals at the outputs of the programmable divider and the reference frequency source is in one direction and a second signal at the second input of the programmable divider when the phase difference is in the opposite direction.

A new active-RC circuit realization of floating inductance

Abstract: A new circuit which uses a single second generation current conveyor (CCII) [1], a single capacitor, and only two resistors and which simulates a lossy frequency-independent floating inductance without requiring any equality constraint is presented.

Active RC single-opamp design of driving-point impedances

Abstract: The active RC simulation of LC filters is of interest, due to the excellent sensitivity properties thereby obtained. Most known designs of active RC driving-point impedances necessary for the simulation of an LC filter, require two opamps per impedance. In this paper a method is presented that realizes general second-order driving-point impedances with only one opamp and with a minimum number of capacitors and resistors. The method is based upon an interesting property of active RC drivingpoint impedances which is derived in the paper. This property relates the well-known properties of driving-point impedance poles and zeros to the zeros of the feedback voltage-transfer functions in a single-opamp secondorder filter structure.

Constant voltage output circuit

Abstract: This invention relates to a constant voltage output circuit using, as its reference potential source, power source feed terminals for feeding a power source voltage to a reference potential source of a given circuit. The constant voltage output circuit includes a series circuit of an npn transistor and a pnp transistor interposed between the reference potential source of the given circuit and the power source feed terminals, means for biasing the base potential of the pnp transistor by a predetermined potential with respect to the potential of the power source feed terminals, and an emitter follower circuit disposed in the collector output circuit of the npn transistor of the series circuit, and forming a negative feed-back circuit.

Capacitive detection of absent and/or double sheets in the sheet transport path of a printing machine

Abstract: A detecting capacitive structure undergoes changes in capacitance value depending upon whether it is detecting, in the sheet transport path of a printing machine, a normal or single sheet, an absent sheet, or a double or stuck-together sheet, so that corrective action can be initiated, such as the skipping of a printing cycle The detecting capacitive structure and also a reference capacitive structure constitute the capacitances of two RC circuit stages to which an input signal is applied and then removed The variations with respect to time of the output signals from the two RC circuit stages are then compared, both during application of the input signal and subsequent to removal of the input signal This comparison of time responses of the two RC circuit stages serves as the basis of the detection The effect of the normal, absent or double sheet upon capacitance value is detected by monitoring a response dependent upon the time-constants of the RC circuit stages, without the detecting capacitive structure forming the capacitor of or resonant circuit

Optoelectronic coupling device for transmitting DC signals

Abstract: There is disclosed an optoelectronic coupling device for transmitting digital signals from an input to an output, which input and output are electrically isolated from each other. An input stage includes an input for receiving digital input signals from an incoming signal line and an output. The input stage is connected to an optoelectronic coupling circuit comprising luminescent diodes and phototransistors arranged adjacent to respective ones of the luminescent diodes. Either the collectors or the emitters of both phototransistors are commonly connected to a first voltage source. The other leads of the phototransistors form outputs of the optoelectronic coupling circuit. An output stage, connected to these outputs, includes an operational amplifier having an output, a non-inverting input and an inverting input. Each of the non-inverting and inverting inputs are connected to one of the outputs of the optoelectronic coupling circuit. The output stage has also two ohmic resistors, each connecting a second voltage source with a respective one of the non-inverting and inverting inputs of the operational amplifier, and a capacitor connected between the non-inverting and inverting inputs. This capacitor and each of said resistors form RC circuits for removing a remaining charge of respective phototransistors when said phototransistors are cut off from saturation.

A design philosophy for microelectronic active-RC filters

Abstract: A design philosophy for microelectronically realizable active-RC filters is presented and illustrated by means of microelectronic filter examples in the frequency range from approximately 75 Hz to about 110 kHz. The design is by simulation of low-sensitivity resistively terminated inductor-capacitor filters (LCR filters). Based on an analysis of the effect of nonideal components in the active-RC filters, functional adjustment methods are developed which lead in practice to near-ideal nominal response characteristics, in many cases better than those of practical LCR filters. By matching the design process to a carefully chosen well-established manufacturing technology, the cost of the microelectronic active-RC filters is attractively low. Many of these filters in microelectronic form are in production in the U.K.

Sequence discriminators and their use in frequency division multiplex-communication systems

Abstract: A simple theory of networks exhibiting sequence discrimination and their use for producing quadrature signals is first presented. A channel unit employing sequence discriminators (SD's), namely, passive (RC), passive with feedback, and active designs are discussed. A channel unit employing SD's and the associated modulation and demodulation schemes are suggested. Statistical sensitivity results and experimental results using thick film resistor and NPO chip capacitor implementations are also given. These indicate that the (SD) approach for single-sideband generation and detection is very promising in FDM applications. This technique which uses resistors, capacitors, and commercial integrated circuits is simple to implement and requires no specially developed technologies.

Constant current electrical circuit for driving piezoelectric transducer

Abstract: An electrical circuit for driving a piezoelectric transducer includes a DC electric source, a constant current circuit, connected to the DC electric source for processing a DC signal from the DC electric source and supplying a constant output current having a predetermined constant value, and an oscillation circuit connected to the constant current circuit for driving the piezoelectric transducer with a resonance frequency and with a constant current. The electrical circuit approximately drives the piezoelectric transducer with a constant current by supplying the constant current to the oscillation circuit.

Some observations concerning the methods of filter/oscillator realization using the concept of FDNR

Abstract: It has been shown that the method of converting a passive RLC low-pass (LP) filter into an inductorless filter using the concept of frequency-dependent negative resistance (FDNR) is equivalent to first applying the low-pass-to-high-pass (LP → HP) transformation and then the RC:CR transformation on the LP filter. Also, the RLC model of an active-RC oscilator and the corresponding RCD model derived from this through Bruton's transformation are RC:CR transforms of each other. The latter observation suggests that many novel oscillator circuits can be generated from existing ones through RC:CR transformation.

Circuit system for the generation of a direct control voltage dependent upon an alternating voltage

Abstract: A circuit for generating a direct control voltage dependent on an alternating voltage, particularly for the generation of a direct control voltage in a system for dynamic compression and expansion, including a storage capacitor for providing the control voltage, at least one electronically controllable charging circuit and at least one electronically controllable discharging circuit connected to the storage capacitor, a comparator for comparing an alternating voltage input signal with a reference value, first and second control circuit paths for connecting the output of the comparator to the control inputs of the charging circuit and the discharging circuit respectively, a time-delay circuit connected in one of the control circuit paths, and an inverter connected in one of the control circuit paths so that the output signals from the two control circuit paths are inverted with respect to one another.

Power regulating inverter circuit

Abstract: A means for regulating the power of a fluorescent tube in a vehicle supplied by a DC source by providing the control circuit of an oscillator transistor of an inverter with an adjustable RC circuit. Even very much dimmed tubes can be lighted with the use of a switch by-passing the RC circuit.

Q-sensitivity of certain RC active filters to gain-bandwidth product

Abstract: The second-order effects of the gain-bandwidth product (g.b.w.) of operational amplifiers on the pole Q of certain active RC bandpass filters have been studied. These studies enable an accurate comparison of various configurations of active filters to determine their utility over a wide range of complex pole frequencies.

A High-Stability RC Circuit Using High Nitrogen Doped Tantalum

Abstract: A fabrication process and reliability studies for RC hybrid integrated circuits utilizing alpha tantalum capacitors and tantalum nitride resistors are described. The alpha tantalum used in this study was reactively sputtered tantalum film containing from 10-20 atomic percent nitrogen and has a body centered cubic structure. The ac and dc characteristics of the alpha tantalum capacitors are in agreement with those shown by Anders and Rottersman [5], [6]. The longterm thermal stability of these capacitors is shown to be at least three times better than for beta tantalum capacitors. Accelerated life tests at various voltages show the alpha tantalum RC circuits to be at least equivalent in reliability to those using standard beta tantalum capacitors. The RC product shows excellent temperature compensation and stability during accelerated parametric aging tests which were done on production RC filter circuits.

Three-terminal electric power source circuit for telephone set

Abstract: PURPOSE: To stabilize a voltage to a telephone set circuit while transmitting an AC signal without distortion even when a DC voltage supplied from a line, by providing a switch circuit controlled with the instantaneous value of the input side voltage of an electric power source circuit. CONSTITUTION: Terminals 3a and 3b are connected to lines at the input side of an electric power source circuit and terminal (c) is connected to a telephone set circuit at the output side. When an input voltage is higher than the sum of the cut-off voltage of constant-current circuit 8 and a voltage across constant-voltage circuit 10, switch 11 stays open through comparing control circuit 12, so that a current input to constant-current circuit 8 will all be supplied to constant voltage circuit 10 via discharge preventing circuit 9. When the input voltage is lower than the sum of the cut-off voltage of circuit 8 and the voltage across constant-voltage circuit 10 and higher than the cut-off voltage of circuit 8, switch 11 is closed by control circuit 12 to supply a constant current to terminal 3b, so that the output voltage of the electric power source circuit will be held constant by a capacitor in circuit 10 and circuit 9. COPYRIGHT: (C)1981,JPO&Japio

Effect of amplifier imperfections on active networks

Abstract: The deviation in the performance of active networks due to practical operational amplifiers (OA) is mainly because of the finite gain bandwidth product B and nonzero output resistance R_0 . The effect of B and R_0 on two OA impedances and single and multi-OA filters are discussed. In filters, the effect of R_0 is to add zeros to the transfer function often making it nonminimum phase. A simple method of analysis has been suggested for 3-OA biquad and coupled biquad circuits. A general method of noise minimization of the generalized impedance converter (GIC), while operating OA's within the prescribed voltage and current limits, is also discussed. The 3-OA biquadratic sections analyzed also exhibit noise behavior and signal handling capacity similar to the GIC. The GIC based structures are found to be better than other configurations both in biquadratic sections and direct realizations of higher order transfer functions.

Circuit for stabilizing frequency of FET oscillator as output power varies

Abstract: A frequency stabilizing device for a FET high-frequency oscillator comprises means for coupling an automatic biasing circuit included in the source-ground connection of the oscillator to a drain voltage supply circuit included in the drain-ground connection of the oscillator to provide simultaneous and oppositely directed variations of the resistance of the automatic biasing circuit and of the value of the drain-ground voltage supplied by the drain voltage supply circuit. A variation of this device can serve as a modulation stage wherein the coupling means comprise a modulating circuit arranged to supply two branches in parallel, each branch comprising a series arrangement of a shaping circuit and an impedance-matching circuit and one of which constitutes the automatic biasing circuit and the other one the drain voltage supply circuit.

Function and operation of the Doublet III E-coil vacuum breaker system

Abstract: The ohmic heating system for the Doublet III fusion research device at General Atomic is required to provide the voltage for the initial breakdown phase (there is no preionization) along with the energy to drive the plasma current to a value of 2.5 MA or greater. This requires a peak one turn voltage of 250 volts (16 kV across coil terminals) and a magnetic flux swing of 5 volt-seconds (peak coil current of 110 kA). This voltage and flux swing is accomplished by reverse biasing the ohmic heating coil (E-coil) where, upon reaching a value of 110 ka the coil current is interrupted and commutated into a RC network producing 16 kV across the coil. The interrruption of the E-coil current is accomplished by the use of an array of vacuum circuit breakers (VCB's) and a counter plus network. A description is given of the ohmic heating circuit and the performance of the vacuum circuit breaker array and its counter pulse system. (MOW)

Filter for separation of two frequency spectra - has resistances of RC filter sections switched between two values at high frequency

Abstract: The spectra are found in the output signal of a measurement sensor of a surface testing instrument. The filter comprises at least one RC section with adjustable pass-band. The resistance of the RC filters (8, 9, 18, 36) can be switched between two values at a frequency higher than the frequency to be separated. Switching-on times of the two resistances, determining the filter (8, 9, 18, 36) cutt-off frequency are adjustable.

More active RC filters using the d.v.c.c.s./d.v.c.v.s.

Abstract: Novel configurations using a differential-voltage-controlled current source, differential-voltage-controlled voltage source (dvccs/dvcvs) as the active building block are described The configurations assume that the active building block is divided into two independent parts initially