Showing papers on "Amplifier published in 1979"

System for transmitting data simultaneously with audio

Abstract: An FM broadcasting system is disclosed for transmitting a data signal simultaneously with an auxiliary audio program on the same subcarriers of an FM transmission channel. The main program is transmitted on the FM transmission channel carrier and the auxiliary audio program, which may be background music, is transmitted on the subcarriers in a conventional manner. According to the present invention, the data signal, which is added to the auxiliary audio program, is a binary digital information signal. This binary digital information signal is used to generate a signal which modulates the phase and amplitude of a data reference signal. The resulting phase transition of the modulated data reference signal represents the binary value of the binary digital information signal. The amplitude of the modulated data reference signal then is adjusted in an automatic gain control amplifier relative to the amplitude of a corresponding frequency range of the auxiliary audio program. This amplitude adjusted signal is combined in a linear summing network with the auxiliary audio program and transmitted over the FM transmission channel. The receiver is capable of receiving one or more of the main program, the auxiliary audio program and the data signal.

Method of and device for synthesis of speech from printed text

Abstract: Upon analyzing grammatically and phonetically a printed text for accents, pauses, intonations and influences of adjacent voice elements in a sentence to be synthesized, a computer loads a plurality of registers including an address counter with instructions for addressing a read-only memory, these instructions specifying rates of counting, numbers or counts, whether counting is to be decremental or incremental and initial addresses of sequences of binary bits coding successive magnitudes of noise signals or of voice-frequency functions. The output of the read-only memory is fed to a loudspeaker via a digital/analog converter and an amplifier whose output is modulated by a signal transmitted from the computer through another d/a converter. The durations of noise and voice-frequency speech elements read out from the memory and the modulation of their amplitudes by the amplifier are randomly modified within ±3% for the frequency and ±30% for the amplitude by the computer to obtain natural-sounding speech from the loudspeaker, while smooth transitions between phonemes or voice elements are attained via the insertion of noise or voice-frequency elements ensuring an even formant or frequency distribution.

Raman pulse compression of excimer lasers for application to laser fusion

Abstract: Application of efficient ultraviolet excimer lasers such as the 248 nm KrF laser to laser fusion requires that long laser pulses be efficiently converted to short pulses at high intensity. The backward Raman amplifier is shown to be a promising candidate for this application. Gain, saturation, and limits to amplifier performance are described. It is shown that pump beams of poor spatial quality may be converted to output beams of high spatial quality. Several common gaseous vibrational Raman scatterers are discussed, and it is shown that a simple KrF-pumped backward Raman amplifier using methane at atmospheric pressure will have a saturation fluence near 1 J/cm2and can produce an output five times as intense as the pump in a ten times shorter pulse with an efficiency of about 50 percent. Design tradeoffs and possible techniques for further improving the performance of such amplifiers are discussed.

Circuit arrangement for attenuation of power oscillations in networks

Abstract: A circuit arrangement, for deriving, from sensed power variations in a network, a signal for supplying the exciter of at least one synchronous machine coupled to the network, includes first and second vector identifiers, each providing a direct and phase-shifted output with each of the outputs coupled through an impedance matching amplifier to a summing junction. The direct signal from the first vector identifier and phase-shifted signal from the second vector identifier are conducted to one summing junction and the phase-shifted output of the first vector identifier and direct output of the second vector identifier to a second summing junction, with the outputs of the two summing junctions summed at a further summing junction after being coupled through additional impedance matching amplifiers to result in a total signal at the output of the third summing junction which varies in a mathematically positive sense with increasing oscillation frequency.

Design of Microwave GaAs MESFET's for Broad-Band Low-Noise Amplifiers

Abstract: As a basis for designing GaAs MESFET's for broad-band low-noise amplifiers, the fundamental relationships between basic device parameters, and two-port noise parameters are investigated in a semiempirical manner. A set of four noise parameters are shown as simple functions of equivalent circuit elements of a GaAs MESFET. Each element is then expressed in a simple analytical form with the geometrical and material parameters of this device. Thus practical expressions for the four noise parameters are developed in terms of the geometrical and material parameters. Among the four noise parameters, the minimum noise figure F/sub min/, and equivalent noise resistance R/sub n/, are considered crucial for broad-band Iow-noise amplifiers. A low R/sub n/ corresponds to less sensitivity to input rnismatch, and can be obtained with a short heavily doped thin active channel. Such a high channel doping-to-thickness (N/a) ratio has a potential of producing high power gain, but is contradictory to obtaining a low F/min/. Therefore, a compromise in choosing N and a is necessary for best overall amplifier performance. Four numerical examples are given to show optimization processes.

Loudspeaker overload protection circuit

Abstract: The output of an audio power amplifier fed to a loudspeaker driver is sensed and when this output exceeds a predetermined level, a switch control circuit operates to place a current limiting device, such as a power resistor, in series with one of the driver feed lines, thereby reducing the power fed thereto. An indicator may also be provided to indicate when the overload condition exists. Operation is made more accurate and distortion minimized by employing separate sensing and power channels in the circuit, the first of these channels operating to sense the overload while the second of these channels utilizes a portion of the amplifier output for driving the switch control circuit for placing the power limiter in the speaker line. The sensing channel is designed to sense the average voltage of the amplifier output, thus providing control more directly responsive to power. The power channel is designed to use audio power from the amplifier output only occasionally, thus producing a minimum of distortion.

Improvement of the gain of MOS amplifiers

Abstract: Techniques for improving the gain of MOS amplifiers are discussed. These techniques depend on technology used. An experimental single stage amplifier was realized using CMOS transistor arrays which achieved gain of 3200.

Ultrasonic wave oscillator circuit with output meter

Abstract: An oscillation system, having a vibrator, a resonant bridge and a low resistance, oscillates at desirable frequencies by receiving an excitation signal amplified to a predetermined value by an amplifier. A detection feedback signal containing the resonant frequency of the vibrator is input to a phase shift circuit. The phase shift circuit adjusts the phase of the detection feedback signal and the excitation signal to satisfy the oscillation condition. The output signal from the phase shift circuit is input to a PLL comprised of a phase comparator, a low pass filter, an amplifier and a voltage controlled oscillator. The frequency of the output signal from the PLL follows the resonant frequency of the vibrator and is locked. Its output signal is applied to the amplifier which feeds the oscillation system. An analog multiplier circuit is fed with signals proportional to the current and voltage from the resonant bridge circuit, and outputs the product of these signals. The output of the multiplier circuit is rectified and applied to a DC meter for indicating power consumption of the vibrator.

A New Method of Broad-Band Equalization Applied to Microwave Amplifiers

Abstract: A new approach to broad-band matching which bypasses analytic gain-bandwidth theory and directly utilizes measured real frequency impedance data is applied to gain equalization and low-noise design of GaAs Shottky-barrier FET amplifiers. Neither the equalizer topology nor the analytic form of the system transfer function are initially assumed. These result from the design process. Examples include an octave-band FET amplifier design and a low-noise FET amplifier design. The equalizers are realized with lumped elements or transmission-fine sections. A single basic least squares program implements the design procedure.

High-resolution A/D conversion in MOS/LSI

Abstract: A new successive approximation analog-to-digital conversion technique compatible with most MOS process technologies is described. This technique combines a string of equal value diffused resistors and a binary ratioed capacitor array in a unique circuit configuration so that 12-bit monotonicity is achieved with only 8-bit ratio-accurate circuit elements. The comparator is realized by a chopper-stabilized amplifier to reduce the inherently high input offset voltages of MOS amplifiers. Typical performance characteristics taken from a sample of ICs are presented; 12-bit monotonic conversion with differential nonlinearity less than 1/2 LSB is completed in 50 /spl mu/s. The die area, less logic, is 12000 mil/SUP 2/. Because of assured 12-bit monotonicity, this converter should find applications of closed-loop control systems. It seems feasible to extend this technique to 14-bit resolution for use in applications such as digital audio systems.

Integrated silicon-PVF 2 acoustic transducer arrays

Abstract: A new type of transducer array has been designed which employs a piezoelectric polymer, polyvinylidene fluoride (PVF 2 ), as the sensing material. Acoustic properties possessed by this piezoelectric polymer provide a reasonable match to those of the human body making it very attractive for medical ultrasonic imaging systems. Using planar integrated-circuit (IC) technology, an array of MOSFET input amplifiers is fabricated on a silicon wafer. A single sheet of PVF 2 is bonded to the surface of the wafer. Spatially varying acoustic signals detected by the PVF 2 are converted to corresponding charge distributions on the underlying array of amplifiers. A linear 34-element receiving transducer array has been built and evaulated. Array transverse dimensions are 14.7 × 9 mm, so that the silicon die area is approximately 1.32 cm2. Individual transducers are 0.42 × 9 mm corresponding to the requirements of a particular system. Associated with each of the 34 transducers is a DMOS-bipolar cascode amplifier. Experimentally measured transducer impulse response decays 20 dB in two cycles. Using silicon technology, arrays of almost arbitrary size and complexity appear feasible.

Storage ring operation of the free-electron laser: The amplifier

Abstract: In this paper we investigate the steady-state features of the free-electron laser amplifier operating with an electron beam stored in a circular accelerating machine (storage ring). The electron distribution and the amplifier output are evaluated. It comes out that the energy transferred from the electrons to the laser beam is proportional to the energy radiated in the bending magnets of the storage ring (synchrotron radiation).

Deep‐level‐transient spectroscopy: System effects and data analysis

Abstract: Studies of typical DLTS systems using either the dual‐channel boxcar averager or the lock‐in amplifier techniques are presented. The effects of nonzero gate width for the boxcar averager, phase angle adjustment for the lock‐in amplifier, and response time of a typical commercial capacitance meter are investigated. Errors introduced in the measurements by these effects are calculated for typical cases. Measurements of the gold donor level in silicon are presented, along with calculated corrections. We find the corrections to be minimal in the boxcar‐averager method, but significant in the lock‐in amplifier approach.

Copper vapor laser unstable resonator oscillator and oscillator-amplifier characteristics

Abstract: We have studied the properties of copper vapor lasers configured as oscillators with unstable resonator optics and as power amplifiers. With the unstable resonator, a 26-fold reduction in the oscillator beam divergence has been achieved over the value observed with stable optics without any power degradation. Time-dependent beam divergence effects in the unstable resonator have also been measured and explained. Small-signal gain, saturation fluence, and available stored energy density parameters have also been measured in oscillator amplifier experiments for both the 510.6 and 578.2 nm transitions as a function of the copper number density. These results quantify the maximum power per unit length available from these devices and furthermore, demonstrate efficient extraction of power from copper vapor lasers operated as amplifiers.

Sensing amplifier for floating gate memory devices

Abstract: An MOS sensing amplifier for sensing the binary state of floating gate memory devices in a read-only memory is disclosed The potentials on the column lines in the memory are held to a narrow voltage swing A pair of "zero" threshold voltage transistors having slightly different threshold voltages are used to maintain the potentials on these lines A potential developed from the column line is compared with a reference potential developed with a "dummy" biasing network and a "dummy" floating gate memory device

Crankshaft position sensor circuitry for providing stable cyclical output signals without regard to peak to peak variations in sensor signals

Abstract: An amplifier circuit for use with Hall effect and other similar type sensors whereby the circuit is conditioned by the cyclical signal input from the sensor and sets a threshold level based upon the signal input from the sensor, so that the signal output from the circuit is a voltage replica of the input signal, but modified to have a predetermined and constant high and low peak values without regard to peak value variations of the cyclical input signal.

Harmonic Load-Pull

Abstract: A unique operator-interactive load-pull system which allows independent tuning of a signal and its harmonics is presented. Various tuning techniques are described and data on MESFET's in amplifier and oscillator configurations is presented.

Ultrasonic wave generating apparatus with voltage-controlled filter

Abstract: The present invention deals with an ultrasonic wave generating apparatus with voltage controlled filter, comprising a phase comparator which detects a shifted value from a predetermined phase difference between a driving voltage or a driving current of an ultrasonic transducer and a vibratory velocity signal, and a voltage-controlled band-pass filter which is controlled by the output of the phase comparator and which is provided in a feedback loop from the vibratory velocity signal to an input of a driving amplifier of the ultrasonic transducer, wherein the oscillating frequency is changed while following the resonant frequency of the ultrasonic transducer, so that stable operation is materialized without developing abnormal oscillation in subresonant frequencies and permitting very small following error.

Characteristics and Optimum Operating Parameters of a Gyrotron Traveling Wave Amplifier

Abstract: Characteristics and optimum operating parameters are determined for a new type of high-power high-efficiency generator of millimeter waves known as a gyrotron traveling wave amplifier. In the example consided, wave amplification results from the interaction of a TE/sub 01/ waveguide mode with the fundamental cyclotron harmonic of an electron beam. The parameter optimization involves the determination of the point of maximum device efficiency as a function of beam density, beam energy, beam positioning, and external magnetic field for the output power required. An analytical linear theory and a numerical simulation code form the basis of theoretical calculations. As a result of the extensive survey in parameter space, the peak efficiency in the beam frame has been found to exceed 70 percent. This result has been applied to the specific design of a 35-GHz amplifier with output power ~340 kW, a power gain of 2 dB/cm, and a laboratory frame efficiency of 51 percent.

A monolithically integrated optical repeater

Abstract: A monolithically integrated optical repeater has been fabricated on a single‐crystal semi‐insulating GaAs substrate. The repeater consists of an optical detector, an electronic amplifier, and a double heterostructure crowding effect laser. The repeater makes use of three metal semiconductor field effect transistors, one of which is used as the optical detector. With light from an external GaAlAs laser incident on the detector, an overall optical power gain of 10 dB from both laser facets was obtained.

The electron cyclotron maser as a high-power traveling wave amplifier of millimeter waves

Abstract: The electron cyclotron maser instability has been exploited as the basis for a new type of traveling wave amplifier which operates at unusually high-power levels at millimeter wavelengths. The first experimental model of this amplifier has been operated at 35 GHz and has demonstrated a stable gain of 17 dB and an output power of 10 kW (unsaturated). The gain was linear over a dynamic range > 30 dB. The absolute value of the gain and its dependence on current and magnetic field were in excellent agreement with theoretical calculations. Bandwidth and saturated power have yet to be measured directly, but no fundamental problems were observed which will prevent successful achievement of the design predictions (viz., bandwidth ≃ 10 percent, power on the order of 105W, efficiency > 10 percent).

Digital communications receiver

Abstract: Receiving apparatus for receiving and detecting binary encoded continuous wave RF signals. The binary signal is detected by a superregenerative detector. The detected signal and a DC reference voltage are applied to an amplifier which produces a signal corresponding to the detected signal but shifted to vary in amplitude about an axis at the DC reference voltage. The shifted signal and the DC reference voltage are applied to a comparator which produces an output signal at a predetermined voltage level when the shifted signal is greater than the DC reference voltage and at 0 volts when the shifted signal is less than the DC reference voltage. Thus a noise-free binary signal having sharply defined voltage transitions is obtained.

Fluidic mud pulser

Abstract: A liquid telemetry system is disclosed useful for transmitting data through a fluid body by means of pulses in the fluid. To generate the pulses in the fluid the system utilizes a bi-stable fluid amplifier in conjunction with a vortex valve. Control input signals direct the flow of fluid from the bi-stable amplifier into the vortex valve in such manner as to selectively impede the flow of fluid through the vortex valve. The resulting changes in fluid flow rates generate pulses within the fluid body.

A monolithic 14-bit D/A converter

Abstract: A monolithic 14-bit D/A converter using `dynamic element matching' to obtain a high accuracy and good long-term stability is described. Over a temperature range from -50/spl deg/ to 70/spl deg/C the nonlinearity is less than one-half least significant bit (/SUP 1///SUB 2/LSB). Dynamic tests show a distortion at a level of about -90 dB with respect to the maximum sinewave output. Nearly no glitches are found, so the converter can be operated without a deglitcher circuit. The chip, with a size of 3.1/spl times/3.2 mm, contains all elements needed, except the output amplifier and digital input latches.

Driving system for an ultrasonic piezoelectric transducer

Abstract: A driving circuit for ultrasonic tools which uses a piezoelectric transducer to convert ultrasonic electric signals into ultrasonic mechanical vibrations including a voltage-controlled oscillator which produces an output signal at a frequency that is proportional to an input voltage, a power amplifier stage having its input coupled to the output of the voltage-controlled oscillator, the power amplifier stage including an output transformer which couples the output of the power amplifier stage to the piezoelectric transducer, the power output transformer further acting as both an insulating transformer and a boosting transformer for the driving circuit and a feedback transformer coupled in series with the secondary side of the output transformer and the piezoelectric transducer, the feedback transformer having a secondary side through which a current flows which is proportional to the current flowing through the piezoelectric transducer, a phase comparitor which detects the phase difference between two signals applied to two inputs of the phase comparitor, the two inputs being respectively coupled to the output signal of the voltage controlling oscillator and the secondary side of the feedback transformer and a low pass filter which blocks high frequency components to pass therethrough connected between an output of the phase comparitor and the input of the voltage controlled oscillator.

Third-Order Intermodulation Distortion and Gain Compression in GaAs Fet's

Abstract: A simple unilateral nonlinear circuit model of a GaAs FET is used in the analysis of the third-order intermodulation distortion and gain compression characteristics of a single-stage amplifier. Expressions are obtained for these characteristics, relating them to the input power level and to the device load admittance. The expressions are illustrated with contours on the load admittance plane of constant intermodulation distortion ratio, intercept point gain compression, AM-to-PM conversion, and output power, and as output power versus input power plots for fixed terminations. Agreement with experimentally measured distortion characteristics is good.

Power line disturbance detector circuit

Abstract: A power line disturbance (PLD) detector circuit includes a digital counter which is driven by pulses provided by a clock in an associated data processing system The PLD detector circuit includes a comparator amplifier for comparing primary AC power to a DC reference voltage on a cycle-by-cycle basis The amplifier generates a reset pulse once during each AC cycle as long as the AC voltage exceeds the DC reference voltage When a decoder circuit detects a count outside the range of counts attained by the digital counter between normally occurring reset pulses, the decoder circuit responds by generating a PLD signal The PLD signal is provided both to the associated data processing system and to a Power On Reset circuit The Power On Reset circuit is initialized by the PLD signal, permitting the circuit to respond consistently upon subsequent restoration of power

Wideband, phase compensated amplifier with negative feedback of distortion components in the output signal

Abstract: A low distortion phase compensated wideband amplifier system includes a low cost, power efficient Class C amplifier positioned along a primary signal path and a feedback loop coupled to provide negative feedback of distortion signal components in the amplified output signal. The negative feedback significantly reduces noise components including intermodulation noise while variable delay phase compensation permits a greater signal to noise ratio over a broader band of frequencies at the system output.

Program controlled capacitive keyboard variable threshold sensing system

Abstract: A sensing apparatus for detecting impedance changes in a variable impedance matrix keyboard. A microcomputer is utilized to control the basic key intersection scanning and for accurately calibrating and adjusting the sensing threshold of the sense amplifier prior to testing each key intersection so that the effects of stray impedance and varying voltage levels may be compensated for. The micro computer supplies sense amplifier sensitivity threshold selection address codes to set the sensing level for the amplifier. Trial drive pulses are applied to a reference capacitor and are gated to the sense amplifier while the sensing level thereof is varied until no output is obtained. This effectively adjusts the sensing circuits for variable voltage power fluctuations occurring over a short time and compensates for variable capacitive effects not associated with actual key switch movements. The micro computer also has a memory containing known stray capacitance values associated with a given keyboard design and these values are also used to compensate by modifying the sensing threshold above or below the calibrated sensing level achieved. Thisis done after driving and measuring the capacitance response until a zero output is obtained so that the sensing level may be individually set for each given key in the matrix at that precise level which can provide the highest non-saturating sensitivity level for the amount of stray capacitance known to be associated with the key and for the existing power and capacitance conditions as originally determined by checking the reference capacitor.