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Showing papers on "Amplifier published in 1974"


Journal ArticleDOI
David Cox1
TL;DR: A technique for producing bandpass linear amplification with nonlinear components (LINC) is described, which produces an amplified and/or translated replica of the original signal.
Abstract: A technique for producing bandpass linear amplification with nonlinear components (LINC) is described. The bandpass signal first is separated into two constant envelope component signals. All of the amplitude and phase information of the original bandpass signal is contained in phase modulation on the component signals. These constant envelope signals can be amplified or translated in frequency by amplifiers or mixers which have nonlinear input-output amplitude transfer characteristics. Passive linear combining of the amplified and/or translated component signals produces an amplified and/or translated replica of the original signal.

654 citations


Journal ArticleDOI
TL;DR: In this article, the effects of pole zero pairs (doublets) on the frequency response and settling time of operational amplifiers were explored using analytical techniques and computer simulation, and it was shown that doublets which produce only minor changes in circuit frequency response can produce major changes in settling time.
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.

300 citations


Journal ArticleDOI
TL;DR: In this paper, the authors described an easily trimmed universal building block for active RC filters which possesses the valuable characteristic that, with suitable design, the Q -value can be made approximately independent of the gain-bandwidth product of the operational amplifiers.
Abstract: An earlier paper by the authors describes an easily trimmed universal building block for active RC filters which possesses the valuable characteristic that, with suitable design, the Q -value can be made approximately independent of the gain-bandwidth product of the operational amplifiers This makes the filter usable for high frequencies, while at the same time the dependence of the Q -value on temperature variations in the operational amplifiers is drastically reduced Design formulas are presented, as well as comparative measurements which verify the theory The building block is shown to have excellent characteristics both as a universal second-order building block and as a standard block for active ladder synthesis of bandpass filters

104 citations


Journal ArticleDOI
TL;DR: In this article, a monolithic sample/hold amplifier is described, which includes the holding capacitor on the chip, and high performance is achieved by the use of a process which produces bipolar transistors and p-channel silicon-gate FET's (SIGFET's) on the same chip.
Abstract: A monolithic sample/hold amplifier is described which includes the holding capacitor on the chip. System design considerations and tradeoffs are discussed, as well as the circuit design details. High performance is achieved by the use of a process which produces bipolar transistors and p-channel silicon-gate FET's (SIGFET's) on the same chip. Performance characteristics obtained include an acquisition time of 10 /spl mu/s (20-V step), an aperture delay time of 80 ns, and a droop rate of 30 mV/s.

97 citations


Journal ArticleDOI
TL;DR: In this paper, the design of an integrated wide-band variable-gain amplifier with maximum dynamic range is approached by considering three basic bipolar transistor configurations from which all others can be derived.
Abstract: The design of an integrated wide-band variable-gain amplifier with maximum dynamic range is approached by considering three basic bipolar transistor configurations from which all others can be derived. The analysis of noise and of distortion shows the importance of transistor base resistance in all three circuits. On the basis of these analyses, one configuration is shown to yield maximum dynamic range, and this configuration is then used as the basis for the development of a new circuit called the improved automatic-gain control (agc) amplifier. A unique biasing scheme allows a considerable reduction in distortion and noise, together with a significant increase in bandwidth compared with conventional circuits.

88 citations


Journal ArticleDOI
TL;DR: In this paper, the noise performance of input amplifiers for optical pulse-code-modulation repeaters is described in terms of an effective noise generator in parallel with the photocurrent induced in the detector and the effective noise, in turn, is related to error performance.
Abstract: This paper describes the noise performance of input amplifiers for optical pulse-code-modulation repeaters. The noise is treated in terms of an effective noise generator in parallel with the photocurrent induced in the detector and the effective noise, in turn, is related to error performance. The analysis applies to both conventional and integrating front ends. Both field effect and bipolar transistor amplifiers are treated. For the latter, an optimum bias current that minimizes the effect of thermal noise is derived. Finally, predicted and measured performance are compared for silicon field-effect transistor input amplifiers at 6.3 Mb/s and 50 Mb/s, and for bipolar transistor and GaAs field-effect transistor input amplifiers at 274 Mb/s.

69 citations


Patent
18 Nov 1974
TL;DR: In this paper, a feed forward system for reducing the distortion products from a device such as an amplifier is proposed, where the distortion sample is adjusted in phase and amplitude and subtractively combined with the device output to produce a distortion-reduced system output.
Abstract: A feed forward system for reducing the distortion products from a device such as an amplifier, wherein a sample of the device input signal is subtractively combined with a sample of the device output signal to produce a sample of the distortion products. The distortion sample is adjusted in phase and amplitude and subtractively combined with the device output to produce a distortion-reduced system output. First and second pilot signals, applied to the device input and output respectively, are detected in the sample of the distortion products and in the system output to produce control signals which adjust the phase and amplitude of the input signal sample and the distortion sample to provide an adaptive system which automatically compensates for uncontrolled variations in the system components. A portion of the distortion sample produced by the feed forward process is fed back to the device input by way of a negative feedback circuit to reduce the signal handling capacity required of components such as an auxiliary amplifier used in processing the distortion sample.

67 citations


Journal ArticleDOI
TL;DR: A unique amplifier configuration is examined that fully exploits the intrinsically high signal-to-noise performance of charge-coupled devices (CCD's) and a floating gate amplifier (FGA) is presented.
Abstract: A unique amplifier configuration is examined that fully exploits the intrinsically high signal-to-noise performance of charge-coupled devices (CCD's). In this amplifier, the signal charge is detected with a conducting `floating gate' embedded in the oxide between a bias electrode and the silicon substrate. The change of voltage on the floating gate produced by the signal charge in the CCD channel is then used to modulate the current flow in a metal-oxide-semiconductor (MOS) transistor. The signal charge remains isolated and can be moved downstream in the CCD channel; thus, it can be detected again by other similar structures. Computer analysis, test structure design, and experimental results of a floating gate amplifier (FGA) are presented.

62 citations


Patent
02 Dec 1974
TL;DR: In this article, an adaptive first mixer of the scanning radio, in response to a signal from a counter in the scanning local oscillator representing the frequency band of the channel being scanned, has its gate electrode connected to the output of a selected RF amplifier of a plurality of RF amplifiers for different bands.
Abstract: To scan channels in a plurality of bands using a single first mixer, an FET transistor in an adaptive first mixer of the scanning radio, in response to a signal from a counter in the scanning local oscillator representing the frequency band of the channel being scanned, has: (1) its gate electrode connected to the output of a selected RF amplifier of a plurality of RF amplifiers for different bands; and (2) its source electrode electrically connected to receive local oscillations through a selected one of a plurality of different impedance networks. These connections enable the adaptive first mixer to maintain sufficiently high conversion gain when receiving signals on channels in any one of a plurality of different frequency bands.

61 citations


Journal ArticleDOI
TL;DR: The design of a wide-band feedforward amplifier in the frequency range 30-300 MHz is described, and the effect of imperfect loop cancellation and circuit imbalance on gain and terminal impedances is investigated.
Abstract: The design of a wide-band feedforward amplifier in the frequency range 30-300 MHz is described. Expressions are derived for feedforward amplifier sensitivity, and the effect of imperfect loop cancellation is described. The effect of circuit imbalance on gain and terminal impedances is investigated. The circuit is realized in thin-film hybrid form, and measurements show 20 dB of distortion improvement at 300 MHz. Practical aspects of circuit adjustment and operation are considered.

59 citations


Journal ArticleDOI
TL;DR: In this article, the design and performance of an X-band amplifier with GaAs Schottky-gate field effect transistors are described, and the amplifier achieves 20 /spl plusmn/ 1.3-dB gain with a 5.5-dB typical noise figure (6.9 dB maximum) over the frequency range of 8.0-12.0 GHz.
Abstract: The design and performance of an X-band amplifier with GaAs Schottky-gate field-effect transistors are described. The amplifier achieves 20 /spl plusmn/ 1.3-dB gain with a 5.5-dB typical noise figure (6.9 dB maximum) over the frequency range of 8.0-12.0 GHz. The VSWR at the input and output ports does not exceed 2.5:1. The minimum output power for 1-dB gain compression is +13 dBm, and the intercept point for third-order intermodulation products is +26 dBm. The design of practical wide-band coupling networks is discussed. These networks minimize the overall amplifier noise figure and maintain a constant gain in the band.

Patent
15 Nov 1974
TL;DR: In this paper, an inductively powered type of electronic transponder for identifying a moving object passing an interrogation area is described, which includes a tuned inductive-capacitive pick-up circuit for receiving interrogating signals and a latching circuit enables a shift register so that the clock pulses serially shift out binary encoded data from the shift register.
Abstract: This disclosure relates to an inductively powered type of electronic transponder for identifying a moving object passing an interrogation area. The transponder includes a tuned inductive-capacitive pick-up circuit for receiving interrogating signals. The picked up interrogating signals are rectified to produce d.c. operating power and are applied to a frequency divider for producing a frequency related transmission signal and clock data rate pulse. A latching circuit enables a shift register so that the clock pulses serially shift out binary encoded data from the shift register. The encoded data is fed to a logic network which is coupled to a balanced switching amplifier for phase modulating the transmission signal for propagation into the interrogation area.

PatentDOI
TL;DR: In this article, a scheme for transmitting wideband signals over a narrow band by directly transmitting low frequency range signals and transmitting amplitude information of partial upper frequency ranges on pilot frequencies is presented.
Abstract: A system for transmitting wide-band signals over a narrow band by directly transmitting low frequency range signals and transmitting amplitude information of partial upper frequency ranges on pilot frequencies is made compatible with existing receivers by making the pilot frequency signals imperceptible in ordinary receivers through the use of a phenomenon known as the masking effect. This is achieved by positive modulation of the pilot frequencies and attentuation to a level 10 db below the level of the low frequency range. If sequential transmission is used, a low level sync signal is produced that does not exceed the signal-to-noise level in existing receivers and is therefore suppressed. In the receivers of the present invention, the low level sync signal is selectively evaluated for control and synchronization of a clock generator but is suppressed below the signal-to-noise ratio of the output and is therefore made inaudible. The sync signal is further processed to control the gain of a modulated pilot signal amplifier and to automatically switch off the upper frequency range signals in the event of sync signal failure or synchronization failure.

Patent
23 Oct 1974
TL;DR: In this paper, a differential input operational amplifier with both inverting and non-inverting inputs connected by way of first and second resistors respectively to an input terminal (the second resistor being in parallel with a first capacitor) is presented.
Abstract: A network particularly useful in thick or thin film circuitry for use in telecommunication systems provides either an all-pass or notch filter function with the same basic component layout but with variously dimensioned component values. The circuit consists of a differential input operational amplifier having both inverting and non-inverting inputs connected by way of first and second resistors respectively to an input terminal (the second resistor being in parallel with a first capacitor) and having its output terminal connected to its inverting input by way of a third resistor and connected by way of a fourth resistor in series with a second capacitor to its non-inverting input, the network having a reference terminal connected by way of a fifth resistor to the junction between the second capacitor and the fourth resistor so as to provide an input port between the reference terminal and the input terminal and an output port between the reference terminal and the amplifier output.

Patent
24 Apr 1974
TL;DR: In this article, a vortex shedding-type flow-metering system is presented, where an obstruction in a flowing fluid develops a series of vortices which are sensed by a pressure-responsive piezo-electric element to produce an alternating voltage having a frequency corresponding to the fluid flow rate.
Abstract: Flow-metering apparatus of the vortex-shedding type wherein an obstruction in a flowing fluid develops a series of vortices which are sensed by a pressure-responsive piezo-electric element to produce an alternating voltage having a frequency corresponding to the fluid flow rate. The piezo-electric voltage signal is processed by electronic circuitry to provide for precise detection of the zero-crossings of the voltage alternations. The resulting frequency signal controls the charge/discharge characteristics of a set of capacitors, with the average charging current corresponding in magnitude to the frequency of vortex shedding. This average current controls an output amplifier in a feedback arrangement to produce a relatively high-powered d-c flow signal over a two-wire transmission line leading to a remote station. In another arrangement, a high-powered pulsating flow signal is developed for transmission over a three-wire transmission line leading to a remote station.

Patent
15 Jan 1974
TL;DR: In this article, an automatic drive control circuit for energizing or driving a sandwich transducer, which includes a mechanical displacement amplifier, piezoelectric crystal drivers and feedback PPI crystals, compares the feedback voltage proportional to displacement and driving voltage.
Abstract: An automatic drive control circuit for energizing or driving a sandwich transducer, which includes a mechanical displacement amplifier, piezoelectric crystal drivers and feedback piezoelectric crystals, compares the feedback voltage proportional to displacement and the driving voltage. The frequency of such driving voltage is automatically adjusted to drive the sandwich transducer at mechanical resonance, which occurs when the feedback voltage equals or exceeds the driving voltage. The drive control includes a sweep circuit coupled to a variable frequency oscillator, which produces an AC square wave signal at a frequency dependent on the sweep signal, and the AC signal is amplified and provided as the driving signal to the sandwich transducer. A comparator compares the driving voltage with the feedback voltage, and when the latter equals or exceeds the former, the sweep circuit locks at a fixed voltage to lock the oscillator AC signal frequency, which is maintained constant while the sandwich transducer is maintained at mechanical resonance.

Journal ArticleDOI
TL;DR: In this article, a temperature controller utilizing a thermistor in a high impedance ac Wheatstone bridge was constructed to maintain the temperature of a 1.3 liter volume to within ±15 μ°C, over a 40h period.
Abstract: We have constructed a temperature controller utilizing a thermistor in a high impedance ac Wheatstone bridge. It maintains the temperature of a 1.3 liter volume constant to within ±15 μ°C, over a 40 h period. The controller employs a ratio transformer, a simple homemade preamplifier, a commercial lock‐in amplifier, a small bipolar power amplifier, and a thermoelectric device. Access to the controlled region can be obtained in a few seconds.

Journal ArticleDOI
TL;DR: A sensitivity analysis for a general second-order multiamplifier RC-active network is described and the proposed configurations are shown to be unconditionally insensitive to variations of the GBWP of the amplifiers.
Abstract: A sensitivity analysis for a general second-order multiamplifier RC-active network is described. The conditions for minimized sensitivity to amplifier gain-bandwidth product (GBWP) are established after first formulating the transfer function gain dependence under the assumption of a single-pole representation of the complex amplifier gain. On the basis of a perturbation technique, approximate expressions are presented for the evaluation of the selectivity and frequency sensitivities. By distinguishing a general form of denominator decomposition, the methods available for realization of high Q's with improved sensitivity are explored. Three special cases of the decomposition are identified; two of these, in common with the general case, suggest the use of twin-T null networks with their attendant high passive sensitivities, but the third gives rise to an additional group of circuits 'realizable as double first-order all-pass sections. By comparison with some previous circuits which require matched amplifiers to achieve a low sensitivity, the proposed configurations are shown to be unconditionally insensitive to variations of the GBWP of the amplifiers.

Journal ArticleDOI
TL;DR: An exact asymptotic method is presented for performing gain calculations on feedback amplifiers and utilizes only Ohm's law, voltage and current division and source conversion and does not require the breaking of the feedback loop.
Abstract: An exact asymptotic method is presented for performing gain calculations on feedback amplifiers. The method is algorithmic and utilizes only Ohm's law, voltage and current division and source conversion and does not require the breaking of the feedback loop. For impedance calculations Blackman's formula is used. A set of quick-reference tables is presented for the most common feedback amplifier configurations.

Journal ArticleDOI
TL;DR: In this paper, the design of a low-distortion, wideband amplifier with 75/spl Omega/input and output impedances is described, and the advantages of a Darlington connection for low distortion are described.
Abstract: The design of a low-distortion, wide-band amplifier with 75-/spl Omega/ input and output impedances is described. Simultaneous shunt and series feedback is used and design equations are derived for terminal impedances, forward gain, loop gain, and noise figure. The advantages of a Darlington connection for low distortion are described. For 0-dBm signal levels, the amplifier achieves third-order intermodulation products of -88 dB relative to the carrier at 300 MHz and 12 channel cross-modulation (CM) of -77 dB at channel 13.

Journal ArticleDOI
TL;DR: In this paper, the basic principles of feedforward are described and both equations and design curves are also described, and two variants of the basic feedforward arrangement are shown to give a more linear output than that available from either separately.
Abstract: Feedforward has largely been ignored as a circuit technique since feedback was introduced in the 1920s. Modern amplifiers can benefit from the application of feedforward as well as feedback and the principle can be applied to both h.f. and X-band amplifiers. The basic principles of feedforward are described and both equations and design curves are included. Two variants of the basic feedforward arrangement are also described. One is arranged for power conservation while the other uses two identical amplifiers at full power to give a more linear output than that available from either separately. The results of these different feedforward arrangements using a pair of proprietary 30 W h.f. amplifiers are included.

Journal ArticleDOI
TL;DR: In this paper, a linear direct reading conductance amplifier which is capable of following conductance changes due to chemical reactions in solution is described, with a sensitivity of 0.05% in each of the six ranges covering 0.025-10-7 Omega -1.
Abstract: A linear direct reading conductance amplifier which is capable of following conductance changes due to chemical reactions in solution is described. It utilizes the simplifications in circuit design offered by operational amplifiers and has a sensitivity of 0.05% in each of the six ranges covering 0.025-10-7 Omega -1. Reactions with half-lives from 2 ms to several hours may be followed.

Journal ArticleDOI
TL;DR: In this paper, it has been shown that an ideal active gyrator can be made with only one amplifier, and its behaviour when used in an inductance-simulating mode is analyzed.
Abstract: Ideal passive gyrators can be made using two operational amplifiers, and it has been proved that they cannot be made with only one amplifier. However, this latter proof led to the discovery that an ideal active gyrator can be made with only one amplifier. A circuit for doing this is presented here, and its behaviour when used in an inductance-simulating mode is analysed.

Journal ArticleDOI
TL;DR: In this paper, the characteristics of the system comprising uniform RC line, charge sensitive terminal amplifiers and waveform shaping filters, as used in the rise-time mode for the location of injected charge signals are described analytically.

Patent
14 Jun 1974
TL;DR: In this article, a load cell fixed beam carries two compression sensitive strain gauges and two tension sensitive strain gauge connected in a Wheatstone bridge circuit to actuate a digital display.
Abstract: Several load cell fixed beams transmit the weight of the useful load of a truck or a scale device from the useful load support to the base structure, such as a truck chassis, or a trailer chassis. The load cell fixed beam carries two compression sensitive strain gauges and two tension sensitive strain gauges connected in a Wheatstone bridge circuit to actuate a digital display. An amplifier or a variable gain amplifier can be provided to intensify the bridge circuit signal. Calibration controls can be provided for setting the readout of the useful load to zero, and further controls can alter the sensitivity of the circuitry to alter the ratio between useful weight and readout.

Patent
26 Jun 1974
TL;DR: In this article, a direct current power supply system for providing power, including standby, to coaxial cable amplifiers in community antenna television networks is presented, where alternating current is rectified and used to power coaxial cables amplifiers spaced along the cable.
Abstract: A direct current power supply system for providing power, including standby, to coaxial cable amplifiers in community antenna television networks Alternating current is rectified and used to power coaxial cable amplifiers spaced along the cable and to maintain a full charge on a storage battery which is continually connected to the input of the cable In the event of failure of the commercial primary power source, the battery feeds power to the cable amplifiers Provision may be made for selectively reversing the output of the power supply to insure that there will be no corrosion deposits caused by electrolysis Finally, the invention also provides circuitry for protecting the storage battery from excessive discharge during power failures of long duration

Patent
06 May 1974
TL;DR: In this article, the first and second operational amplifiers are connected in a positive feedback loop to measure relative humidity within a given environment, where the first amplifier supplies an input signal to the second amplifier enabling the second Amplifier to provide an amplified output signal which is fed back to an input of the first Amplifier.
Abstract: Apparatus for measuring relative humidity within a given environment includes first and second operational amplifiers connected in a positive feedback loop. The first amplifier supplies an input signal to the second amplifier enabling the second amplifier to provide an amplified output signal which is fed back to an input of the first amplifier. First and second thermistors, which sense dewpoint and ambient temperatures, respectively, within the environment, control the gain of the second amplifier in accordance with changes in relative humidity to permit the second amplifier to provide an output signal which varies linearly with percent relative humidity.

Patent
26 Aug 1974
TL;DR: In this paper, an electronic switch which has no moving parts and is actuated by the capacitance of an operator providing a connection between earth ground and an input to the electronics associated with the switch is disclosed.
Abstract: An electronic switch which has no moving parts and is actuated by the capacitance of an operator providing a connection between earth ground and an input to the electronics associated with the switch is disclosed. The electronic switch in the preferred embodiment, includes a plate accessible to the tough of a human operator electrically connected to a first amplifier, and particularly to the input which is isolated from and thus oscillating with respect to earth ground. The output of the first amplifier is simultaneously connected to one end of a storage capacitor, having its other end connected to earth ground, and to one end of a high impedance. A second amplifier, is connected to the other end of the high impedance to provide a switched output, with the switched output having a first state for approximating an electrical short circuit and a second state for approximating an electrical open circuit.

Journal ArticleDOI
TL;DR: In this paper, a systematic RC-active network synthesis procedure for the realization of second-order transfer functions is proposed, which employs a single generalized impedance converter which can be implemented by using only two operational amplifiers.
Abstract: A systematic RC-active network synthesis procedure for the realization of second-order transfer functions is proposed. The realization employs a single generalized impedance converter which can be implemented by using only two operational amplifiers. The sensitivity to passive element variations are found to be low. The sensitivity to variations in the amplifier d.c. gain is minimized and found comparable to that in other low sensitivity structures. A design procedure is developed in which tuning can be achieved by trimming only resistors. With the exception of one case, second-order sections can be cascaded without additional isolating amplifiers. The stability properties as well as the influence of the finite bandwidth of the amplifiers are examined. The design procedure is used to obtain a sixth-order Chebychev low-pass filter, and a sixth-order elliptic band-pass filter. Experimental results show that these realizations are insensitive to temperature and power supply variations.

Patent
Julius Gluck1
15 Aug 1974
TL;DR: A linear direct current amplifier with automatic gain control system for regulating the peak-to-peak amplitude of the signal output that is acquired by scanning a coded label with a hand-held photo optical scanner is disclosed in this article.
Abstract: A linear direct current amplifier with automatic gain control system for regulating the peak-to-peak amplitude of the signal output that is acquired by scanning a coded label with a hand-held photo optical scanner is disclosed. The gain is set primarily by the white background on the coded label and it is further adjusted at the black bar as the pen passes over the label surface on which the code is imprinted. Control circuit feedback compensates for input amplitude and contrast variations.