Showing papers on "Amplifier published in 1982"

Quantum limits on noise in linear amplifiers

Abstract: How much noise does quantum mechanics require a linear amplifier to add to a signal it processes? An analysis of narrow-band amplifiers (single-mode input and output) yields a fundamental theorem for phase-insensitive linear amplifiers; it requires such an amplifier, in the limit of high gain, to add noise which, referred to the input, is at least as large as the half-quantum of zero-point fluctuations. For phase-sensitive linear amplifiers, which can respond differently to the two quadrature phases ("$cos\ensuremath{\omega}t$" and "$sin\ensuremath{\omega}t$"), the single-mode analysis yields an amplifier uncertainty principle---a lower limit on the product of the noises added to the two phases. A multimode treatment of linear amplifiers generalizes the single-mode analysis to amplifiers with nonzero bandwidth. The results for phase-insensitive amplifiers remain the same, but for phase-sensitive amplifiers there emerge bandwidth-dependent corrections to the single-mode results. Specifically, there is a bandwidth-dependent lower limit on the noise carried by one quadrature phase of a signal and a corresponding lower limit on the noise a high-gain linear amplifier must add to one quadrature phase. Particular attention is focused on developing a multimode description of signals with unequal noise in the two quadrature phases.

Adaptive biasing CMOS amplifiers

Abstract: Two transconductance amplifiers are presented in which the concept of an input dependent bias current has been introduced. As a result, these amplifiers combine a very low standby power dissipation with a high driving capability. The first amplifier, suited for SC filters, is fairly small (0.075 mm/SUP 2/) and has a slew rate which is more than an order of magnitude better than micropower amplifiers presented earlier. The second amplifier can be used as a micropower buffer. Nearly the whole supply current is used to charge the load capacitor so that this amplifier has a high efficiency.

Implantable dynamic pressure transducer system

Abstract: A pressure and motion transducer and cooperating circuitry for an implantable medical device are disclosed. The system includes a pressure transducer 48 and buffer amplifier 40. A clock 70 in pacer 52 periodically energises amplifier 40 via capacitor 62 and lead system 54. The voltage sensed across sensing resistor 74 at node 78 is applied to sample and hold circuit 66 and a continuous pressure signal is provided at output terminal 82.

RF Circuit Design

Abstract: It's Back! New chapters, examples, and insights; all infused with the timeless concepts and theories that have helped RF engineers for the past 25 years! RF circuit design is now more important than ever as we find ourselves in an increasingly wireless world. Radio is the backbone of today's wireless industry with protocols such as Bluetooth, Wi-Fi, WiMax, and ZigBee. Most, if not all, mobile devices have an RF component and this book tells the reader how to design and integrate that component in a very practical fashion. This book has been updated to include today's integrated circuit (IC) and system-level design issues as well as keeping its classic "wire lead" material. Design Concepts and Tools Include .The Basics: Wires, Resistors, Capacitors, Inductors .Resonant Circuits: Resonance, Insertion Loss .Filter Design: High-pass, Bandpass, Band-rejection .Impedance Matching: The L Network, Smith Charts, Software Design Tools .Transistors: Materials, Y Parameters, S Parameters .Small Signal RF Amplifier: Transistor Biasing, Y Parameters, S Parameters .RF Power Amplifiers: Automatic Shutdown Circuitry , Broadband Transformers, Practical Winding Hints .R F Front-End: Architectures, Software-Defined Radios, ADC's Effects .RF Design Tools: Languages, Flow, Modeling Check out this book's companion Web site at: http://www.elsevierdirect.com/companion.jsp?ISBN=9780750685184 for full-color Smith Charts and extra content! *Completely updated but still contains its classic timeless information *Two NEW chapters on RF Front-End Design and RF Design Tools *Not overly math intensive, perfect for the working RF and digital professional that need to build analog-RF-Wireless circuits

A Monolithic GaAs 1-13-GHz Traveling-Wave Amplifier

Abstract: This paper describes a monolithic GaAs traveling-wave amplifier with 9-dB gain and +-1-dB gain flatness in the 1-13-GHz frequency range. The circuit is realized in monolithic form on a 0.1-mm GaAs substrate with 50-Omega input and output lines. In this approach GaAs FET's periodically load input and output microstrip lines and provide the coupling between them with proper phase through their transconductance. Experimental results and the circuit details of such a structure are discussed. Initial results of a noise analysis and predictions on the noise performance are also given.

Wide-band distributed rf coupler

Abstract: A wide-band distributed coupler for coupling rf energy from an input waveguide into a tapered interaction waveguide in a traveling-wave amplifier comprising a plurality of channel filters connecting between the input and interaction waveguides, with each filter coupled to the interaction waveguide at the appropriate cross-sectional position along its tapered length where the interaction waveguide cutoff frequency approximately matches the wave frequency propagated by the filter. Each filter comprises, in one embodiment, a main coaxial cavity tuned to a distinct center frequency, a first simple isolation cavity for coupling rf energy between the input waveguide and the main cavity, and at least one second simple isolation cavity for coupling energy between the main cavity and the tapered interaction waveguide. This coupler is compatible both in bandwidth and geometry with the tapered interaction waveguide.

A Simplified "Real Frequency" Technique Appliable To Broadband Multistage Microwave Amplifiers

Abstract: A computer-aided design procedure, a simplified "Real Frequency" technique, applicable to broadband, multistage FET amplifiers is presented. The design procedure requires no decisions to be made in advance as to algebraic form of transfer function, or circuit topology. Furthermore it is more efficient, accurate and complete than currently-available CAD methods.

Laser drilling system utilizing photoacoustic feedback

Abstract: A laser drilling control system utilizing photoacoustic feedback is described. The control system provides an accurate monitoring of the laser drilling of a multilayered printed circuit board thereby allowing uniform drilling through layers of different optical and photoacoustic properties by both analyzing the photoacoustic feedback signals received, and adjusting optimally the laser parameters such as pulse duration, wavelength, energy, pulse repetition rate, and the number of pulses, for each successive layer. The system also provides an end point detection which prevents underdrilling overheating, and overdrilling of underlying layers and associated damages. According to another aspect of this invention, the control system can be used as a sensitive misregistration detector for aligning the laser beam to a selected drill site for subsequent drilling at the selected drill site.

Electronic safety device for controlling the drive motor attached to a sliding window

Abstract: Apparatus for an electrically moved sliding window used in automotive applications, having a built-in safety device is described. This detector is a proximity detector which detects the approach of a portion of a human body, e.g. a gloved hand. This detector is advantageously comprised of a capacitive pickup carried along the upper edges of the window, connected to a detector stage which, as a function of the rate of change in the signal appearing across the pickup, acts, via an amplifier, to remove the electrical power supplied to the drive motor of the window.

Power-line baseband communication system

Abstract: A communication system for transmitting baseband digital signals (16) on an electrical power line (12). A pulse generator (14) produces digital signals which are limited to a frequency spectrum of 30 kHz to 300 kHz and applied directly, i.e., without modulation, to an electrical power line. At the receiving terminal (25) an amplifier (32) compensates for attenuation characteristics of the electrical power line and the received signal is then sampled (34) to extract the information from it. To avoid interference when both a transmitting and receiving link are located at a substation, the baseband system incorporates a mimic network to mimic the interference signal erroneously picked up by the receiving link from the transmitting link located at the same substation. The mimic signal is then subtracted from the interference signal to neutralize the effect of the latter. When both a baseband digital communication system and a carrier communication system utilize the same electrical power lines, provision is made for interrupting the baseband digital signal to allow communications via the carrier system.

Advances in lock-in amplifiers

Abstract: The key specification points of lock-in amplifier systems for signal recovery and signal characteristics are reviewed and it is shown how these can be improved and modified by more advanced system design. The configurations of several commercially available systems are described and the facilities available in computer-controlled lock-in systems are discussed briefly, together with some new application areas.

Analysis of the settling behavior of an operational amplifier

Abstract: The settling behavior of a pole-splitting compensated operational amplifier is analyzed using a second-order (two-pole) transfer function. It is shown that although the slewing period of the amplifier is well approximated by the commonly used formula for slew rate, the settling behavior after the slewing period can only be fully explained using a second-order transfer function. Simple criteria relating the circuit parameters to the damping ratio of a second-order feedback system are given. Analytical expressions for the amplifier responses and settling times are derived. The analysis is justified by close correspondence with computer simulations.

Dual mode amplifier

Abstract: An apparatus amplifies a signal in two different modes. The apparatus amplifies the signal in a linear mode when the voltage of the signal is much less than the voltage of the power source, and in a switching mode when the signal is at other voltages.

Phase modulated switchmode power amplifier and waveform generator

Abstract: A phase modulated DC-to-AC or a DC-to-DC power converter utilizes input terminals connected to a source of power and output terminals connected to a suitable load. The transfer of power between the power source and the load or from the load back to the power source is accomplished by electronic switching that is phase displaced controlled in all four quadrants.

Self-consistent large signal theory of the gyrotron travelling wave amplifier

Abstract: A self-consistent large signal theory is developed for the gyrotron travelling wave amplifier with the sever. The theory allows for tapering of both the magnetic field and the waveguide cross-section along the axial direction. A computer code for the large signal theory has been tested for the rectangular gyrotron amplifier circuit with the sever where the RF wave is completely terminated. For a circuit with uniform cross-section, we find 50% optimum efficiency and 52 dB gain when there is no axial velocity spread. At 10% axial velocity spread, the efficiency becomes 37%. The tapered two-stage gyrotron travelling wave tube (gyro-TWT) considered in this paper gives rise to 20% bandwidth and 40 dB total gain for zero axial velocity spread. The tapered case is much more sensitive to the beam velocity spread than the uniform guide.

Modern multistage depressed collectors—A review

Abstract: Well performing multistage depressed collectors (MDC's) have been developed for traveling-wave tubes (TWT) in an sizes fitting the requirements of wide-band countermeasures, radars, and ground and space communications. In the case of NASA-type symmetric collectors, rigorous analytical tools were developed that permit accurate a priori designs of MDC's for any given helix-type tube. Although only few verified cases of MDC's augmenting communications klystrons are known, the resulting performance and available theories indicate significant gains in reducing power consumption by TV and other klystron amplifiers without the deleterious effects of backstreaming.

Design of amplifiers and oscillators by the S-parameter method

Abstract: This book presents a modern approach to the design of amplifier and oscillator circuits. While many electronics firms now depend on scattering-parameter designs in their product lines, there has been no single reference source to the fundamentals, tools, and applications of the S-parameter method. This book serves practicing designers as a working guide to S-parameter design, with emphasis on impedance-matching techniques that do not require the use of a computer. The book's sections cover basic concepts and tools, amplifier designs, and oscillator designs. The first chapter introduces S-parameter two-port network theory and the definitions of power gain. Chapter Two describes microwave transistors, microstriplines, and impedance-matching techniques. This chapter includes a brief description of the most important threeterminal microwave transistors, the silicon bipolar transistor, and the GaAs MESFET Following this introduction, the book discusses actual designs and design problems. Chapter Three is devoted to amplifier designs, including the special considerations of balanced-amplifiers, high-power, broadband-amplifiers, feedback, and two-stage-amplifier designs. Basic limitations in device and circuit performance are discussed for each design. The final chapter deals with oscillator design, introducing the compressed Smith Chart and the application of S-parameters to oscillator circuits. Low-noise, high-power, broadband, and buffered oscillator design considerations are treated in this chapter. Design of Amplifiers and Oscillators By The S-Parameter Method will help the thinking of the design engineer who is using computer-aided design, which can be a risky, expensive solution to a poorly understood design problem. Engineers will find it a source of practical day-to-day guidance in microwave device and circuit design. Advanced students will find it an outstanding introduction to S-parameter techniques as well as to current microwave components.

Automatic brightness control apparatus

Abstract: Automatic brightness control apparatus for providing real time control of the brightness of various types of displays while also providing ambient light compensation is disclosed which includes a photodiode for providing a current proportional to the ambient light level. Amplifiers, together with a load, change the photodiode current to a control voltage indicating the level of ambient light. The control voltage is provided as a reference input to a voltage comparator. The other input to the voltage comparator is the output of a free running ramp oscillator. The pulse width modulated logic signal comprising the output of the voltage comparator is provided as the input for an output driver whose pulse stream output is used to control the brightness of the designated display. The duty cycle of the pulse stream output varies with the ambient light level. Several logic gates are added to the free running ramp oscillator to provide synchronization capability and assure that the ramp output waveform of the ramp oscillator will always begin with an incoming synch pulse. The automatic brightness control apparatus is packaged as a monolithic integrated circuit on a single silicon chip which is housed in a clear plastic 8 pin DIP.

Device for the compensation of hearing impairments

Abstract: An exemplary embodiment includes a plurality of parallel signal channels coupled with a signal input transducer, such as a microphone or induction coil. Each of the signal channels includes a respective bandpass filter for selection of a different frequency band, a controlled-gain amplifier, controlled by a volume control potentiometer, circuits for non-linear signal processing, and a bandpass filter for the reduction of distortion components caused by the non-linear processing circuits. A summing amplifier combines the signal components from all channels and is connected via an amplifier to an output signal transducer. Space requirements and power consumption are reduced in such a multi-channel processing arrangement by implementing all of the filters as sampled-data analog circuits. As a result hearing aids are provided which can be worn on the head, e.g. behind the ear.

Baseband linearizer for wideband, high power, nonlinear amplifiers

Abstract: The baseband linearizer attenuates the amplitude of the in-phase and quadrature phase components of the baseband signal as a function of the transfer characteristic of the high power amplifier and under the control of a baseband signal power level detector. The phase angle of the attenuated signal is rotated as a function of the amplifier transfer characteristic, again under the control of the power level detector.

Ultra-Low-Noise 1.2- to 1.7-GHz Cooled GaAsFET Amplifiers

Abstract: A 3-stage GaAsFET amplifier operating at 13 K, utilizing source inductance feedback is described. The amplifier has a noise temperature of 15 dB over the 1.2- to 1.7-GHz frequency range.

Projection display system

Abstract: Projection display systems implemented with illumination amplifiers, such as liquid crystal devices, are provided. High intensity illumination is used to provide a high intensity large screen display. Heat transfer devices are used for removal of heat, which is caused by the high intensity illumination, from the illumination amplifier. The illumination amplifiers can be implemented in either transmissive or reflective modes. In a reflective mode, illumination is reflected from a front side and heat is removed from a back side of the illumination amplifier. Color is provided, such as generating multiple channels of different color images and projecting the different color images to generate a multi-colored image. Various system configurations are provided; such as a high intensity projection liquid crystal television system, a scoreboard display system, and a billboard display system.

A DC-12 GHz Monolithic GaAsFET Distributed Amplifier

Abstract: A monolithic balanced traveling-wave amplifier stage using GaAs MESFET's is demonstrated. The amplifier achieves 7-9-dB gain with about 40-ps risetime and a -3-dB bandwidth of 12 GHz, on a 0.91 X0.97-mm die. Its gain versus frequency is very flat, and |S/sub 11/|, |S/sub 12/|, and |S/sub 22/| are less than 0.2 from 0-18 GHz. S-parameter uniformity and yield data are measured on-wafer with a special hybrid wafer probe.

NLA-QAM: A Method for Generating High-Power QAM Signals Through Nonlinear Amplification

Abstract: A generalized technique for generating quadrature amplitude modulated (QAM) signals that permits nonlinear amplification is presented. With this technique a high-power 2^{2n} -state QAM signal is generated by combining n unfiltered, nonlinear amplified, QPSK signals, n being a positive integer. The specific methods of generating 16- and 64-state signals using this technique are presented. An attractive feature of the technique is that despite significant difference with the conventional method of generating QAM signals, the same straightforward demodulation techniques apply to both, and the P e versus S/N performances are essentially identical. In the 16-state version employing traveling wave tubes (TWT's) or GaAsFET amplifiers, the technique is shown to result in a transmitter output power advantage that is on the order of 5 dB compared to the conventional method. This advantage is achieved, however, at the expense of an additional output power amplifier.

Fast Timing Methods for Semiconductor Detectors

Abstract: This tutorial paper discusses the basic parameters which determine the accuracy of timing measurements and their effect in a practical application, specifically timing with thin-surface barrier detectors. The discussion focusses on properties of the detector, low-noise amplifiers, trigger circuits and time converters. New material presented in this paper includes bipolar transistor input stages with noise performance superior to currently available FETs, "noiseless" input terminations in sub-nanosecond preamplifiers and methods using transmission lines to couple the detector to remotely mounted preamplifiers. Trigger circuits are characterized in terms of effective rise time, equivalent input noise and residual jitter.

Touch type input device

Abstract: PURPOSE:To eliminate the undesired input and to improve the operability, by providing a pressure detector at the lower side of an input touch plate, comparing the touch pressure with the reference level and inhibiting an output when the touch pressure is lower than the reference level. CONSTITUTION:Piezoelectric converting elements 6a-6c are provided on a support plate 5 and at the lower side of a touch type input plate 1. These piezoelectric converting elements are connected to the negative terminal of operational amplifier 7 via resistances R1-R3. Thus a touch pressure detecting means 2 is obtained. The output of the amplifier 7 is fed to the positive terminal of a comparing means 3 and compared with the reference voltage of the negative terminal. When the output of the amplifier 7 is higher than the reference voltage, ''1'' is delivered and fed to an AND circuit 9. A signal corresponding to a touch point is fed to another input 10 of the circuit 9. Then the circuit 9 delivers an output only when the touch pressure is higher than the prescribed level. The reference voltage of the negative terminal controls a constant resistance VR of a level setting means 4 to set a desired level of touch pressure. As a result, an input due to an inadvertent contact is inhibited and the touch pressure is set at a desired level to improve the operability of a touch input device.

CCD Demodulator circuit

Abstract: A semiconductor integrated circuit using charged coupled device (CCD) technology for performing demodulation of time-varying signals which have been phase or amplitude modulated. The CCD circuit performs a sampling of the time-varying signal at a suitable sampling frequency depending upon the frequency of the phase or amplitude modulation of the carrier. The CCD device converts the sample into an equivalent charge packet which is used to control the control electrode of a field effect transistor in an amplifier circuit. The magnitude of the sample is representative of the amplitude of the carrier so that the output of the field effect transistor represents a demodulated signal. The circuit is a broad spectrum device, operable with a signal frequency from the audio into the gigaHertz (GHz) frequency range.

Gate-coupled field-effect transistor pair amplifier

Abstract: An enhancement mode (104, 204, 404) and a depletion mode (102, 202, 402) pair of N-channel MOS transistors have their drain-source conduction paths connected in series and provided with a bias current means (120, 220, 306, 410) The gates (106, 206, 308, 310) are coupled together as an input node In one embodiment (100) their bulk regions are source-connected and the output (118) is from the source of the enhancement mode device (104) to obtain a source follower configuration amplifier In a second embodiment (200), the output (218) is taken from the drain (208) of the depletion mode device (202) to obtain a common source configuration amplifier Two source follower pairs (302, 304) are disclosed connected in parallel to form a differential input voltage amplifier stage (300) A common source pair (402, 404) is disclosed in combination with an additional enhancement mode transistor (406) to form a current mirror (400)

Gain saturation in Nd:doped laser materials

Abstract: Saturation of gain in Nd:doped silicate, phosphate, and fluorophosphate glasses, and in doped crystals of YAG and YLF was observed during amplification of 1064 and 1053 nm pulses with durations of 1.0, 9.0, and 50 ns. Saturation fluences were computed from measured external parameters by means of the Frantz-Nodvik model for a homogeneous amplifier. The resulting values of saturation fluence increase with increasing output fluence and were only slightly greater at 50 ns than at 1 ns, suggesting that the lower level lifetime is less than 1 ns.

Switched capacitor DSB modulator/demodulator

Abstract: An integrated single-sideband modulator comprises six integrated capacitors C1-C6 and first switch means alternately connecting C1 and C2 as feedback capacitors across a differential input operational amplifier A1. The amplifier has a virtual ground potential on its inverting input terminal for causing it to operate as a voltage source and render the circuit relatively insensitive to parasitic capacitance effects associated with capacitor plates. Second switch means cooperates with A1, C1 and C2 and is responsive to 4-phase clock signals for driving input capacitors C3-C6 so as to convert first and second quadrature-phase input signal voltages into first and second electrical charge flow signals on the inverting input terminal that are a function of products of representations of the first and second voltages in switch state time intervals and associated pulse trains which have a 90° phase difference therebetween and a repetitive pattern such as +1, +1, -1, -1, etc. The amplifier and feedback capacitors combine the charge signals for producing a single-sideband signal on A1's output terminal. This circuit is converted to a balanced modulator by omitting C5 and C6. In an alternate embodiment of a single sideband modulator that requires only a pair of switched capacitors C11 and C12, a 4-phase switch means alternately charges C11 and C12 with associated ones of the quadrature-phase input signal voltages while alternately connecting C12 and C11 as feedback capacitors across A1, the polarity of each capacitors feedback voltage being reversed each time that capacitor is connected across the amplifier. This circuit is operated as a balanced modulator by omitting one of the capacitors.