Showing papers on "RC circuit published in 1970"

Broad-Band Equivalent-Circuit Determination of Gunn Diodes

Abstract: A method has been developed for the direct broad-band measurement of the impedance of a Gunn diode operating at a bias voltage exceeding threshold. This method is based upon determination of an equivalent-circuit model for the diode mount and package, which is found to be valid over the 1- to 20-GHz range. Using this circuit, the low-field diode equivalent circuit is found and takes the form of a parallel RC circuit as expected from the theory. An unusual result is that the low-field capacitance is found to be strongly dependent on the bias voltage; this dependence is presumed due to the free-carrier contribution to the effective dielectric constant. Some direct broad-band measurements are reported for an active Gunn diode biased beyond threshold. These measurements provide additional insight into the conditions under which significant parametric action may occur in a Gunn diode.

Temperature control system with a pulse width modulated bridge

Abstract: A temperature control system is disclosed which includes a modified wheatstone bridge with a resistive-capacitive (RC) circuit in one leg of the bridge. The RC circuit includes a resistor which provides an effective resistance as a function of its absolute resistance and the on-time to off-time ratio of pulses supplied to a switch connected thereacross. A sawtooth voltage is produced across the RC circuit, the voltage being compared with the voltage across a temperature sensor, with heat being applied during each pulse period portion when the sawtooth voltage exceeds the voltage across the temperature sensor.

Converter for changing alternating current into direct current

Abstract: A converter for changing alternating current into direct current by charging a large-capacity capacitor through a full wave rectification circuit which, together with a transformer, is connected to an AC power supply The output voltage of a voltage divider circuit consisting of the above-mentioned capacitor and a parallel-connected resistor is compared with a predetermined reference voltage by a comparator circuit Then, if the former is lower than the latter, a gate circuit is triggered to put a selfoscillating circuit into a state where it is ready for oscillation, and the oscillating operation of the above-mentioned self-oscillating circuit is triggered through the gate circuit connected to an intermediate point of a closed loop made up of a rectification circuit for rectifying an AC source voltage and of a part of the aforesaid voltage divider circuit, the output of the self-oscillating circuit providing a trigger signal for a thyristor means connected to the aforementioned transformer

A sine wave oscillator

Abstract: A closed-loop oscillatory system, comprising an RC differentiator, a new type of an RC network and two transactors in cascade is described. For certain system conditions the circuit produces a sine wave oscillation whoso frequency is varied over a wide range from a very low to a high value. The main feature of the system is that the generation of a very low frequency oscillation is possible without incorporating a large value of the RC product. The frequency relation is derived and the results are presented in graphs.

High speed frequency shift keyed transmission system

Abstract: A frequency shift keyed data transmission system utilizes a transmitter comprising an oscillator for producing a series of output voltage pulses whose repetition rate is governed by the time constant of an associated RC circuit, a key switch for altering the resistance of the associated circuit-thereby altering the pulse repetition rate-and a conversion circuit for converting the pulses into sinusoidal output waves having a frequency proportional to the pulse repetition rate. This transmitter is capable of transmitting data at high bit rates without introducing significant frequency transients. A receiver which utilizes a discriminator comprising circuitry similar to that of the above-described transmitter can be used to detect FSK information in a manner which is substantially independent of variations in the signal amplitude.

Unified modeling scheme for semiconductor devices with applications of state-variable analysis

Abstract: A unified scheme for modeling semiconductor devices is presented. The main feature of this scheme is that it can be directly applied to state-variable analysis. A distributed system based on continuity, current-flow relationship, and Poisson's equations is shown to be approximated by a lumped RC network with arbitrary accuracy. By means of this modeling scheme and state-variable analysis technique, a network composed of semiconductor devices is formulated by a set of ordinary differential equations. The lumped RC network contains some C-only cutsets and circuits, which correspond to Poisson's equation and the conservative nature of the electrostatic field, respectively. From these topological structures, a set of state equations of a minimum number of independent variables is systematically obtained. An example of formulating a set of state equations of a twodimensional transistor model is given as are suggestions for applying the modeling scheme to various kinds of semiconductor devices. The modeling scheme proposed can be efficiently applied to the analysis of both the device itself and a network consisting of many devices over a wide range of conditions.

Active rc networks

Abstract: An active RC network formed by a voltage amplifier and a passive RC feedback network connected in a negative feedback loop with the amplifier. The negative feedback network is able to receive a resistance such that when the resistance is zero, there are no zeros in the transmission of the feedback network (phantom zeros), and when the resistance is finite, there are complex conjugate phantom zeros in the right half of the complex frequency plane. For any given value of the quality factor Q of the network response, both the required amplifier gain and the sensitivity of the circuit to gain and component changes are small, with the value of the phantom-zero-determining resistance being selected to achieve a desired trade-off between the values of the gain and the sensitivity. In certain embodiments, the passive RC network includes a distributed RC element in which the resistive portion of the distributed element is connected between the output and input of the voltage amplifier. If the amplifier is a simple voltage amplifier, the phantom-zero-determining resistance is connected in series between the network input terminals and the conductive portion of the distributed element. This conductive portion may also be divided into one or more parts connected to the common connection between the input and output of the network, thereby improving the selectivity by introducing a zero at infinity. If the amplifier is a differential amplifier, the phantom-zero-determining resistance is connected in series between the conductive portion of the distributed element and the input-output common connection.

Universal active unit for active RC-circuit synthesis

Abstract: A complementary pair of embedding principles for the differential-input earthed-output operational amplifier are combined to obtain a general-purpose resistive embedding which is universal from the strict synthesis point of view in that all four types of controlled source (`transactor´) may be realised with either sign.

A new look at distributed RC notch filters

Abstract: A new approach to the study of distributed RC notch filters is presented. The method is intended to impart a clearer understanding into the mechanism which causes the null to appear. It also leads to the introduction of different forms of notch filters than those previously considered.

Skin Effect and Proximity Effect in Polyphase Systems of Rectangular Conductors Calculated on an RC Network

Abstract: The parameters of polyphase transmission lines consisting of two or three equal parallel rectangular conductors are calculated for low and high frequencies An analog RC network with about 3300 nodes has been built which allows the diffusion equation and Laplace's equation in an infinite plane to be solved, and which lends itself favorably to the method of virtual displacement, too From measurements on this network, the coefficients of resistance and internal inductance per unit length are given for the even and odd modes of two-conductor transmission lines and for Clarke's ?-s-0 components of three-conductor transmission lines The results can be used to calculate the influence of proximity effect on resistive and inductive losses in busbar systems and cables with rectangular conductors carrying arbitrary phase currents Besides these results, methods are indicated to determine the capacitance per unit length, the electric and magnetic fields, and the magnetic forces between current-carrying conductors by means of the analog network It is believed that the method for direct measurement of serial losses and the curves in Figs 4?10 for the proximity effect of rectangular conductors are new

A circuit for converting a variable frequency pulse train into a related electric voltage

Abstract: A frequency-to-DC converter circuit for producing an output voltage related to the frequency of a train of input pulses. The circuit includes an improved ''''diode pump'''' circuit in which the input capacitor discharges through a diode only to a given reference voltage different from ground potential during the period between successive input pulses. The reference voltage approximates the instantaneous voltage across the circuit storage capacitor. The output voltage is preferably taken from the junction of an RC time constant circuit. The converter is especially adapted to provide a speed signal in an anti-lock brake system.

Active realization of nonminimum phase RC transfer functions

Abstract: A method of realizing transfer functions having poles on the negative real axis and zeros anywhere in the s plane is presented. The circuit uses an inverting amplifier of maximum gain unity and a minimum phase RC network in a dual-input unbalanced configuration. The theory is illustrated by two examples of biquadratic nonminimum phase RC transfer functions, of which one is an all-pass type. The sensitivity of the realizations to active and passive element variations is also discussed.

Synthesis of symmetrical RC and RL lattice networks with maximum gain and minimum number of elements

Abstract: New methods of synthesizing symmetrical lattice networks using resistors and capacitors, or resistors and inductors, are presented in the paper. The methods permit the synthesis of any transfer function that is a ratio of output voltage or current, to input voltage or current, as long as the transfer function satisfies the conditions of physical realizability of transfer functions with RC or RL networks. The load impedance can also be specified as long as it is realizable with an RC or RL network. A transfer function is synthesized by synthesizing an equivalent open-circuit voltage transfer function that is derived from the desired transfer function and load impedance. The resulting network is then modified, and the desired transfer function with the given load is obtained. Two root-loci plots are used in the synthesis procedures, as well as in a proof that any open-circuit voltage transfer function satisfying the conditions of physical realizability of RC transfer functions can be synthesized using the prescribed method. The network, resulting from the synthesis of an open-circuit voltage transfer function, has maximum gain and a minimum number of elements, if desired.

Computer-aided design of distributed RC networks

Abstract: In this paper, synthesis of distributed RC networks using nonlinear programming is investigated. The Fletcher-Powell minimization procedure is used to minimize the integral squared error. At the same time, the decreasing of the error in the Chebyshev sense is examined in each iterative cycle. One of the main considerations in applying nonlinear programming to a design problem is to find an initial design such that, by iterating it in the frequency range of interest, the iteration is guaranteed to converge to a minimum within a reasonably short computing time. Two methods for finding such an initial design are presented. One is to make an approximation of the given network function in a transformed complex frequency domain. Both approximations are obtained by means of orthogonal functions. The methods presented in this paper may be used for practical distributed RC network applications. Examples are given to illustrate the methods.

Rc networks and amplifiers employing the same

Abstract: The active filter circuit of the present invention comprises a passive RC network and a DC voltage or operational amplifier. The resistive and capacitive elements of the passive RC network determine the location of a pair of complex conjugate zeros along the j omega axis. Connected to the RC network in shunt are a load resistor and a load capacitor. A feedback network interconnects the output of the voltage amplifier with the passive RC network. By regulating the value of the load resistor and the value of the load capacitor jointly or severally, the location of a pair of complex conjugate poles produced by the active filter can be adjusted separately and independently from the zeros. In addition thereto, the regulation of the gain of the DC voltage or operational amplifier or the changing of the feedback voltage of the DC voltage or operational amplifier adjusts independently the location of the pair of complex conjugate poles relative to the zeros. When a plurality of active filter circuits are connected in cascade, a frequency-selective amplifier is formed with the DC voltage or operational amplifiers serving additionally as isolation devices between successive active filter circuits. It is to be observed that each active filter circuit produces real frequency zeros of transmission at any desired frequency independently of the location of complex poles with respect to the zeros.

A high-Q distributed-lumped-active network configuration with zero real-part pole sensitivity

Abstract: A circuit is introduced which requires a single distributed network, a resistor, and an amplifier of approximately unity gain to produce a transfer function with a pair of high-Q dominant complex conjugate poles with zero real-part sensitivity.

Timed cycle warp stop-motion control for weaving looms

Abstract: A circuit is disclosed for controlling the energization of the solenoid for actuating the conventional power-stop motion of a weaving loom in the event either of power failure or of breakage of warp threads. A silicon-controlled rectifier (SCR) is connected in series with the solenoid and an AC voltage supply. Gating of the SCR is controlled by a unique transistor flip-flop circuit, the state of which is responsive to two different threshold voltages established at a control point. The voltage at the control point is determined by an RC charging and discharging circuit conditionally responsive to the drop wire contacts. The RC circuit is adjusted so that a definite charging time must elapse after the opening of the drop wire contacts until the flip-flop changes state to gate the SCR into conduction. This time is made longer than the time of a pick-cycle of the loom.

Cascade synthesis of distributed networks by lumped ladder RC equivalents

Abstract: This paper suggests a new presentation for the transmission-line networks. In the same way as Richards' presentation, in which the frequency transformation t = tanh sT was used to convert a class of transmission-line networks into lumped networks consisting of L, C, and unit elements, the frequency transformation q = sinh' sT is now used for converting the cascade transmissionline networks into a lumped ladder network consisting of R, C, and possibly an ideal transformer at one end. The new equivalent network maintains a one-to-one relationship with the components of the transmission-line network without doubling the number of components. It has the advantage that the final network presentation is a lumped two-element-kind network. Classical network theories can therefore be applied directly. For purpose of illustration, the cascade unit-element network and cascade unit-loop network are considered in detail. It is shown that the cascade unit-element network can be presented by a ladder RC network, and the cascade unit-loop network by a mid-series low-pass RC network. The continued-fraction expansion technique and the zero-shifting technique can therefore be used, respectively, for the synthesis of the two networks.

Autopolarity voltmeter circuit

Abstract: A highly-sensitive circuit for an electrical instrument for causing the indicator on a meter to read linearly upscale for positive or negative DC signals, AC signals, or a combination of AC or DC signals applied to the input of the circuit The input signal to be measured is provided to an input circuit which includes a resistive divider network in circuit with a null control circuit for selecting the range of input signals A selected proportion of the input signal is applied to the input of a field effect transistor (FET) The output from the FET is applied to the input of a transistor having its output in circuit with a bridge network The bridge network includes a pair of oppositely poled diodes in circuit with fixed resistors so that a first diode conducts for positive signals and a second diode conducts for negative signals from the transistor A meter is connected in circuit with the diodes and is arranged so that the indicator on a meter reads upscale whether the output of the amplifier comprises positive or negative DC signals or AC signals or a combination of both A feedback circuit includes a resistive network in circuit with the bridge for selecting the appropriate circuit sensitivity for the function to be performed by the circuit The output from the resistive network in the feedback path is connected to a pair of transistors connected in a Darlington configuration, the output of which is connected to the FET The input circuit also includes a switching circuit for providing a coupling capacitor in series circuit with the input signals to block DC when AC signals are being measured, and to provide a low pass filter in circuit with the input signals when DC signals are being measured The circuit according to the invention may be also be used to measure resistance and current The method of using the circuit of the invention is also disclosed wherein the indicator on the meter is caused to indicate a null reading in the absence of an input signal to the circuit by adjusting the null control circuit and sensing the indicator on the meter until a null is reached The null control circuit may also be used to provide a storage feature for the circuit

Synthesis of low-pass linear-phase active circuits using distributed RC networks

Abstract: An active-feedback distributed RC network capable of matching the magnitude response of a pair of complex-conjugate poles and simultaneously giving linear phase is described. The linearity of the phase response is further improved when exponentially tapered \overline{RC} networks are utilized. It is shown that such characteristics can be used for simultaneous realizations of flat magnitude response and linear phase. Butterworth magnitude responses having phase linearity associated with those of transitional Butterworth-Thomson filters and Thomson magnitude responses having better phase linearity than those achievable by active lumped RC networks can be realized by cascading these circuits. In addition, it has been found that exponential tapering substantially reduces the required gain and the Q sensitivity to changes in gain for a given pole position. Reduction in gain with improvement in Q sensitivity to changes in gain makes these circuits attractive for high-frequency applications.

Constant amplitude-variable phase circuit

Abstract: An electronic circuit including an operational amplifier having a differential input stage coupled to passive linear input and feedback circuit components for converting three wire synchrotype data to an equivalent constant amplitude-variable phase signal.

Sinusoidal oscillations in active RC filters

Abstract: A feedback system consisting of an amplifier and an activo RC filter hag been described. It is observed that for certain variations in the filter configurations and for both positive and negative gains of tho amplifier sine wave oscillation is generated in the system for specific system conditions. The frequency of oscillation can be varied over a wide range by the variation of the gain of the amplifier. Expressions for the frequencies of oscillations in the oscillatory modes have been given and the conditions of oscillations have been derived. The analysis has been experimentally supported.

Active RC bandpass filter with independent tuning and selectivity controls

Abstract: The design of a stable active RC bandpass filter for general-purpose laboratory use is presented. Noninteracting controls are provided for frequency Q and peak gain.

On generation of RC impedance functions

Abstract: Several new results on the generation of realizable RC driving-point functions from given RC impedance function(s) are described. Applications of some of these results have led to new necessary relations on the coefficients of the numerator and denominator polynomials of RC and RLC driving-point impedance functions.

Capacitor soakage compensation

Abstract: 1,166,211. Integrators. APPLIED DYNAMICS Inc. 8 Jan., 1968 [27 March, 1967], No. 1117/68. Heading G4G. In an integrator circuit having compensation for capacitor leakage and absorption, a differential operational amplifier U 1 has an input resistance and an integrating feedback capacitor C 1 incorporating leakage and absorption represented (Fig. 2a, not shown) by an ideal capacitor shunted by a leakage resistance and plural series RC circuits representing absorption. A pair of negative feedback circuits comprising resistance and capacitance in series, C4R 3 , C2R 2 , from output to earth with functions connected to input over capacitances C 5 , C 3 simulate and cancel absorption, while leakage is simulated and compensated by positive feedback resistance RX connected from output to the second input of the operational amplifier. Alternatively (Fig. 3, not shown) a positive feedback resistance from input to an intermediate point of the amplifier simulates and compensates leakage, and one of the negative feedback circuit comprises a capacitance and resistance in series across the integrating capacitor. Other compensating feedback networks comprise a resistance voltage divider at the output connected to input over a resistance/capacitance T-section (Fig. 4, not shown) or a capacitance voltage divider at the output connected to input over a resistance/capacitance L-section (Fig. 5, not shown). A mathematical analysis is given.

L-c oscillator tunable by external dc voltage through phase shifted feedback network

Abstract: An L-C oscillator circuit is tunable as a function of the value of an externally applied DC voltage. The phase of the resonant circuit is shifted 90* by a phase shifting circuit and the amplitude of the output of the phase shifting circuit is controlled by the externally applied DC voltage. A current, the amplitude of which is proportional to the controlled output of the phase shifting circuit is generated by a current generator and fed back to the resonant circuit. As this current is shifted 90* out of phase, the capacitive element of the resonant circuit is controlled by controlling the output of the phase shifter by means of the applied DC voltage. A wave shaping circuit may be used to convert the output of the phase shifting circuit from a sinusoidal to a square wave.

On the synthesis of any RC-realizable rational transfer function using a nonuniform RC distributed circuit

Abstract: A synthesis procedure that can realize any RCrealizable rational transfer function as the open-circuit-voltage transfer ratio of a nonuniform, passive RC distributed circuit is presented. The resulting circuits have a simple, standardized topology and can be readily constructed by thin-film techniques. The synthesis procedure has been completely programmed on a digital computer. From the specification of the transfer function and the electrical properties of the construction materials, the computer produces the complete geometry for the construction of the distributed circuit.

A three-layer distributed RC network with two transmission zeros

Abstract: This report describes the properties of a three-layer distributed RC network consisting of two resistive layers separated by a dielectric which may be used to realize two zeros of transmission on the j-omega axis of the complex frequency plane. The relative location of the two zeros is controlled by the location of a contact placed on one of the resistive layers.