Showing papers on "Frequency response published in 1974"

A simple three-terminal IC bandgap reference

Abstract: A new configuration for realization of a stabilized bandgap voltage is described. The new two-transistor circuit uses collector current sensing to eliminate errors due to base current. Because the stabilized voltage appears at a high impedance point, the application to circuits with higher output voltage is simplified. Incorporation of the new two-transistor cell in a three-terminal 2.5-V monolithic reference is described. The complete circuit is outlined in functional detail together with analytical methods used in the design. The analytical results include sensitivity coefficients, gain and frequency response parameters, and biasing for optimum temperature performance. The performance of the monolithic circuit, which includes temperature coefficients of 5 ppm//spl deg/C over the military temperature range, is reported.

Relationship between frequency response and settling time of operational amplifiers

Abstract: The effects of pole-zero pairs (doublets) on the frequency response and settling time of operational amplifiers are explored using analytical techniques and computer simulation. It is shown that doublets which produce only minor changes in circuit frequency response can produce major changes in settling time. The importance of doublet spacing and frequency are examined. It is shown that settling time always improves as doublet spacing is reduced whereas the effect of doublet frequency is different for 0.1 and 0.01 percent error bands. Finally it is shown that simple analytical formulas can be used to estimate the influence of frequency doublets on amplifier settling time.

Simplified impedance/frequency‐response results for intrinsically conducting solids and liquids

Abstract: The small‐signal ac response is considered of a system containing a single species of positive charge and a single species of negative charge. The charge carriers may be of many different types (ions, electrons, vacancies, etc.) and are assumed to have arbitrary mobilities and valences. Quite general boundary conditions are considered which encompass the range from complete blocking to zero blocking (infinite reaction rate at the electrodes) for positive and negative charges separately. The present paper deals primarily with approximations to an earlier exact solution of the problem which, in general, lead to an equivalent circuit made up of three parallel R C combinations in series. The elements of one of these parallel circuits, associated only with bulk effects, are frequency independent, and those of another, which are associated with nonzero blocking, may often be well approximated as independent. The third R C section arises from diffusion effects, involves frequency dependent elements, and exhibits...

Analysis of Response of Pyroelectric Optical Detectors

Abstract: Several configurations of pyroelectric optical‐radiation detectors are mathematically modeled to determine their frequency response and current response to step‐function heat inputs. Included in the analysis are heat losses by conduction and reradiation, effects of absorptive coatings, and an experimentally observed nonuniformity of polarization through the thickness of polymer pyroelectric films. Roll‐off of the frequency response at both low and high frequencies is carefully examined. Curve fitting to response data allows a quantitative determination of the pyroelectric coefficient and the degree of nonuniformity of the polarization. The thermal conductivities of gold blacks used as absorbers are determined from the high‐frequency data together with independent measurements of the black thicknesses and densities. The total emissivity of evaporated nickel films sometimes used as absorbers can be estimated from the low‐frequency data. The difference in response to optical and electrical heat inputs is exa...

Electronic Circuits and Applications

Abstract: Partial table of contents: LEARNING THE LANGUAGE. Fundamental Concepts. Linear Resistive Networks. Dependent Sources. Operational Amplifiers. Capacitance and Inductance. ELECTRONIC DEVICES. Electrical Conduction Processes. Diode Circuits and Applications. Physical Electronics of Transistors. Large-Signal Transistor Circuits. Small-Signal Models and Circuits. LINEAR CIRCUITS AND SYSTEMS. Linear System Response. Frequency Response in Linear Systems. Signal-Processing in Linear Systems. APPLICATIONS.

Efficient Numerical Computation of the Frequency Response of Cables Illuminated by an Electromagnetic Field (Short Papers)

Abstract: Computationally efficient numerical methods for determining the frequency response of uniform transmission lines consisting of a large number of mutually coupled conductors in homogeneous and inhomogeneous media, and illuminated by an electromagnetic (EM) field are presented.

Synchronous Machine Operational Impeadances From Low Voltage Measurements at the Stator Terminals

Abstract: Models of a synchronous machine for use in stability studies have been derived by measurements off-line at standstill. The method involves accurate determination of magnitude and phase of the impedance as seen at the stator terminals, for a range of frequency from 0.005 to 100 Hz. The data obtained pertains particularly to establishment of parameters for equivalent rotor circuits of varying degrees of complexity.

A new frequency domain technique for the simplification of linear dynamic systems

Abstract: This paper presents ft method for approximating a higher-order linear system transfer function by a lower-order model. The method is based on the requirement that the frequency response of the simplified model is to be matched with the frequency response of the original system. The frequency response matching is required in using simplified models for the analysis of nonlinear control systems. The reported new method is illustrated by means of a numerical example. A critical comparison of this method with other existing methods of model simplification is also presented.

A two-dimensional model for the lateral p—n—p transistor

Abstract: A two-dimensional solution of the continuity equation in the base of the lateral p-n-p transistor, including interactions with the substrate and subdiffused layer, is presented for dc excitation. This method is extended to the case of steady-state sinusoidal excitation. Computed and measured results are presented for the frequency dependence of the Short-circuit small-signal current transfer ratios, and comparison of these shows reasonable agreement over the full range of measurements. An approximate equivalent circuit derived from a single-pole fit to the frequency response of short-circuit admittance parameters is inferred to be valid Up to a few megahertz for the device considered.

Velocity correction circuit for video discs

Abstract: Velocity and phase errors in signals derived from a rotating video disc are minimized with the use of a voltage controlled oscillator and an electromechanical transducer. A control circuit employing an active and a passive filter maintains an appropriate frequency response to the voltage controlled oscillator and electromechanical transducer in order to appropriately share a single controlling error signal.

Two-dimensional frequency domain filtering

Abstract: This specification discloses an automatic computer-implemented technique for filtering a two-dimensional array of data in the frequency domain. The program converts the array of numbers by Fourier transformation into the real and imaginary part of the frequency domain. In this domain, undesired waves present in the original array can be completely removed by the elimination from the frequency domain of the components of the Fourier-transformed array which fall within (or, if desired, outside of) a convex polygon of arbitrary shape. The system then re-transforms the remaining data back to the time domain, but the undesired components have been filtered. The program can cause the computer to produce a visual reproduction of the filtered array, or it may simply re-format the data of this array on a tape for further computer processing. Accordingly, this invention permits precision spatial filtering of undesired components from the original array. The original array may represent the digitized data from a seismic section, or the amplitude and frequency response of a two-dimensional array of geophones to a steady state alternating seismic wave from a source. A rapid version of large automatic Fourier transformation and re-transformation is included.

Nonlinear acoustic propagation in two-dimensional ducts

Abstract: The method of multiple scales is used to obtain a second-order uniformly valid expansion for the nonlinear acoustic wave propagation in a two-dimensional duct whose walls are treated with a nonlinear acoustic material. The wave propagation in the duct is characterized by the unsteady nonlinear Euler equations. The results show that nonlinear effects tend to flatten and broaden the absorption versus frequency curve, in qualitative agreement with the experimental observations. Moreover, the effect of the gas nonlinearity increases with increasing sound frequency, whereas the effect of the material nonlinearity decreases with increasing sound frequency.

A computer controlled apparatus for measuring AC properties of materials over the frequency range 10 -5 to 10 5 Hz.

Abstract: The apparatus described is capable of measuring materials with loss tangents down to 3*10-3 although it is hoped in the future to improve this to 3*10-4. The apparatus is based on a Solartron frequency response analyser which is used to measure the voltage across and the current flowing through the sample. Complete computer control is available with on-line calculation of results enabling frequency sweeps to be performed in the minimum time. The results are available as printed data, punched tape or plotted on an XY recorder. Possible errors in the measurement are discussed.

Limitation of Correction of Frequency Dependent Artefact in Pressure Recordings Using Harmonic Analysis

Abstract: Frequency dependent phase and amplitude distortion may theoretically be minimized using correction formulae derived from a model which assumes that water-filled catheter-manometer systems are analogous to an oscillating mass attached to a spring and damping pot. This study defines the practical limits of this correction technique using harmonic analysis of simultaneously recorded water-filled and catheter-tip manometer systems. Some improvement was obtained in tracings recorded with underdamped, high frequency response systems. In no case were exact duplications of the catheter-tip tracings obtained. Divergence of measured vitro frequency response from actual in vivo frequency response was one source of these discrepancies. Loose coupling of the components of the system also changed the behavior from that of the assumed simple mechanical model and at times prevented adequate correction. Catheter-tip manometers, in spite of their expense and relative fragility, still appear to be the best means at present of obtaining accurate pressure tracings, particularly at high heart rates or where time derivatives are to be computed.

Circuit arrangement for frequency division by non-integral divisors

Abstract: A circuit arrangement for generating an output frequency by division of an input frequency by adjustable divisors. Use is made of a first adjustable frequency divider having an output wherefrom the output frequency is derived, and a further frequency divider which is connected as an adjustable selection circuit and the counting input of which receives the output frequency. The input frequency is applied to the counting input of the first frequency divider via a gate. The output of the selection circuit is connected to one input of the gate such that each output signal of the selection circuit suppresses a given number of pulses of the input frequency.

The postural response of normal dogs to sinusoidal displacement

Abstract: 1. Normal dogs were trained to adopt a laterally symmetric stance on a horizontal platform. Sinusoidal oscillation of the platform in the cephalocaudal direction caused the dogs to adopt a strategy of response which would keep them from falling down during the period of imposed motion or perturbation. 2. A Fourier analysis of the response variables provided a quantitative measure of the distortion in the induced movement at the various hind leg joints and in the motion of the body. Certain aspects of the distortion could be accounted for by recognized random events such as drift and panting. The remainder of the distortion was task related and therefore provided evidence that the dog's postural control system behaved essentially as a non-linear system. 3. The motion of the body was less distorted than the motion at the joints. The frequency response of the body motion resembled that of a second order linear system, but the amplitude of the body motion did not vary in constant proportion with changes in the amplitude of the input. Further, the phase relation between body motion and platform motion was not constant when the amplitude of the input was changed. Therefore, it was concluded that the control of the body position was probably non-linearly related to the input disturbance but that the low pass filter characteristics tended to minimize the appearance of distortion in that system output. 4. Control of the position of the hind limb is related to the control of the torque generated at the hind limb joints. To the extent that joint angle and change in joint angle are related to the torque at a joint, the distortion of the motion at the joints clearly demonstrates that control of the hind limb during this postural task was non-linearly related to the sinusoidal input. 5. The uniformity of the response parameters, as assessed from the Fourier coefficients, indicated that all of the tested dogs adopted the same or nearly the same strategy for solving the problem of adjusting their postural control in response to the perturbation. Therefore, a reasonable hypothesis for future testing is that the central programme which generates this particular postural response will be structured similarly from one dog to the next.

Monolithic acoustic imaging transducer structures with high spatial resolution

Abstract: A method is described for simplifying the construction of high‐resolution imaging transducers by using impedance matching transformers on a monolithic plate structure. Simple physical arguments are used to establish the general design criterion that a broad frequency response leads to a wide angular response and high resolution. This conclusion is verified by numerically computed performance curves for a particular air‐backed transducer structure.

Phase modulation and self-modulation of light in three-photon processes

Abstract: An analysis shows that phase changes in the phase-matched conversion of the frequency of light in piezoelectric crystals can be utilized in fast-response self-bleachable filters and controlled switches. A one-dimensional steady-state approximation is used to study phase modulation of a weak signal in up or down frequency conversion in a transparent piezoelectric crystal pumped at a fixed level. The same approximation is used in considering phase self-modulation of the pumping radiation under frequency doubling conditions. Dependence of various quantities on the input amplitude are obtained for different degrees of detuning; these quantities are the relative intensity and phase shift of the pumping radiation at the output of a frequency doubler, and the degrees of self-bleaching and bleaching in the case of parametric amplification and frequency addition.

Polyphase alternator with single phase output

Abstract: An alternating current electrical power generator of the rotating field type whose output frequency is independent of the rotational speed of the field. Low frequency electrical power is produced by generating a high frequency polyphase voltage which is rectified alternately positive and negative and by simultaneously modulating the level of the high frequency voltage with a low frequency sine wave.

The measurement of the charge residual for CCD transfer using impulse and frequency responses

Abstract: By developing a model for the impulse response of a single phase CCD a simple equation is derived which relates the ratio of the first two pulses of the impulse response to the charge residual ϵ. When this is extended to practical multiphase structures it is shown that this equation is independent of the number of clock phases used in a CCD. Using Z transforms an expression for the frequency response of a CCD is derived in terms of ϵ. Values for the charge residual are obtained by experimental measurement of impulse and frequency responses and these are compared to test the validity of the model used.

Synthesis of transfer function from frequency response data

Abstract: This article presents a method of obtaining an analytical expression for the transfer function of a system in the form of a ratio of two polynomials of the complex variable, 8, from the frequency response- data. The method alleviates the deficiencies of some of the other methods previously reported in the literature. First, it guarantees that the denominator polynomial, when factorized, would not have right-half plane poles and, second, there is no need to know the degrees of the numerator and denominator polynomials, a priori. By systematically examining the time response of the synthesized transfer function, say to a unit step function, the method guarantees that the form and the coefficient values of the transfer function which is finally arrived at do give the best fit to the frequency response data. The minimum mean square error criterion is used to judge the goodness of fit.

Complete identification of a class of nonlinear systems from steady state frequency response

Abstract: Measurement of the steady state response to a sinusoidal input has long been an important technique for the identification of linear systems. In this paper we consider this approach to identification for the class of nonlinear systems shown in Figure I.

On a Piezoelectric Flapper Type Servovalve Operated by a Pulse-Width-Modulated-Signal

Abstract: As a first step to developing a servovalve with minimum moving parts, a new servovalve is devised in which a piezoelectric flapper (a quartz strip) is used instead of a conventional flapper actuated through a torque motor. A servovalve of this type is desirable from the viewpoint of fast response, however it has not been in common use because of the strong hysteresis of piezoelectric material. In order to linearize the nonlinear characteristics of the flapper, a pulse width modulated wave is used as the input signal to the flapper. The frequency characteristics of the pulse width modulator is theoretically analyzed in detail to establish the theoretical basis of the pulse width modulation control system. As well-known, this basis has been ambiguous so far. The experimental frequency responses show that the bandwidth of the servovalve using this new technique is comparable to that of conventional valves having the same power output in spite of its simple construction in comparison with conventional ones.

Maximally flat nonrecursive two-dimensional digital filters

Abstract: The maximally flat criterion is extended to the design of two-dimensional nonrecursive digital filters which approximate circularly symmetrical low-pass specifications. Straightforward generalization of the one-dimensional method does not completely specify the coefficient matrix of the filter. The additional degrees of freedom can be used to increase locally the order of flatness at the origin and/or at the Nyquist frequencies. The choice of the local conditions is crucial, in particular for what regards the monotonic behavior outside the axes. Concentration of the local conditions on the diagonal of the frequency plane gives a special class of filters which, besides the advantage of closed-form expressions for the coefficients, has a monotonically decreasing frequency response along any radius of the frequency plane.

Frequency-variation method for system identification

Abstract: A frequency-variation method is established for identifying a linear system transfer function from a single set of frequency response data. The method generally applies three different Cauer continued fraction forms. Based on the real and imaginary parts of the frequency response data, a corresponding transfer function can be identified. The identification processes can be carried out with a digital computer.

Frequency Content of Intravascular and Intracardiac Pressures and Their Time Derivatives

Abstract: The purpose of this study was to determine the frequency content of intravascular pressures and their time derivatives. Pressures, recorded using catheter-tip manometers in patients undergoing diagnostic cardiac catheterization, were amplified, filtered (100 Hz) to minimize aliasing errors, and then converted to digital format at 200 samples/sec. After examination of the waveform to exclude obvious artefact, it was analyzed using a Fourier transform and then resynthesized using a decreasing number of harmonics. Peak dp/dt of both the original and resynthesized waveforms was computed until marked differences were observed.

Apparatus for determining the phase difference between the rolling oscillation of a ship and a liquid contained in a stabilizing tank

Abstract: The measured rolling rate of a ship and a measured liquid level difference in a liquid contained in a stabilizing tank are supplied to frequency dependent members having identical frequency response to obtain a derived roll angle and derived level difference after which a circuit is provided to measure the phase difference between the quantities developed and to develop an output analog voltage representing the difference between a desired relationship between the phases of the two and the actual phase relationship.

Transformerless input for seismic data acquisition system

Abstract: In a long line data acquisition system, an input network is provided for coupling the lines to a data acquisition unit. The network includes the cascade combination of a first filter presenting a low pass frequency response to common mode voltage and a second filter presenting a low pass frequency response to difference mode voltage. The output of the second filter is coupled to an amplifier having high common mode rejection. The network substantially reduces, at the amplifier input, both common mode and difference mode noise picked up by the lines.