Showing papers on "Noise (electronics) published in 1978"

Conversion Loss and Noise of Microwave and Millimeterwave Mixers: Part 1--Theory

Abstract: An analysis is presented for the conversion loss and noise of microwave and millimeter-wave mixers. The analysis includes the effects of nonlinear capacitance, arbitrary embedding impedances, nonideality of microwave diodes, and shot, thermal, and scattering noise generated in the diode. Correlation of down-converted components of the time-varying shot noise is shown to explain the "anomalous" noise observed in millimeter-wave mixers. Part 1 of the paper presents the theoretical basis for predicting mixer performance, while Part 2 compares theoretical and experimental results for mixers operating at 87 and 115 GHz.

Pyroelectric detectors and materials

Abstract: A survey on point pyroelectric detectors and materials is given. The performance of a practical detector is characterized by the ratio of a response function and a noise function. Material parameters relevant to detector applications are identified and the crystal properties of these parameters are then discussed by the use of equations of state. The noise function is so defined that the performance of the practical pyroelectric detector as a circuit element can be directly examined and assessed with respect to the ideal thermal detector. Under special conditions, this noise function gives rise to four separate figures of merit of pyroelectric detectors. Finally the temperature dependence and the performance limitations of pyroelectric detectors are discussed.

Graded channel FET's: Improved linearity and noise figure

Abstract: The characteristics of GaAs field-effect transistors were examined as a function of the channel doping profile in the direction perpendicular to the surface. Theoretical considerations predict that improved device linearity is expected for channel doping profiles with relatively low carrier concentrations near the surface. These predictions are experimentally confirmed by comparison of GaAs FET's fabricated with uniform (flat) and exponentionally varying (graded) carrier concentrations as a function of depth. In addition, the graded devices are observed to exhibit noise figures approximately 1 dB lower than those of uniformly doped devices of the same geometry.

Noise in Solid State Devices

Abstract: Publisher Summary The purpose of this chapter is to present a survey of noise in solid-state devices. This chapter also discusses the various noise sources and this is applied to p-n junction diodes, Schottky barrier diodes, tunnel diodes, Josephson junctions, bipolar transistors, junction field effect transistors (JFETs), and metal-oxide-semiconductor field effect transistors (MOSFETs) The most important sources of noise in solid-state devices are thermal noise, shot noise, generation-recombination (g-r) noise, and flicker noise. Moreover, for semiconductor material one encounters noise due to the generation and recombination of carriers. It shows up as fluctuations in the resistance of the sample that can be detected, in turn, by applying a voltage to the sample and measuring the fluctuating current. For simple cases, the noise can be described by one fluctuating number of carriers; either electrons or holes. This is true for the noise due to traps, deep-lying donors or acceptors, Shockley-Read-Hall centers when there is a predominant lifetime.

Co-Channel Interference of Spread Spectrum Systems in a Multiple User Environment

Abstract: This paper considers the mutual interference problem of several users employing the same spread spectrum technique in selected multiple user environments. The spread spectrum techniques consist of pseudo noise (PN), time division multiple access/PN, synchronous and asynchronous frequency hopping (FH). The environment consists of a desired transmitter-receiver pair located in an area where there are M interfering users distributed in accordance with a specified probability density function. Both coherent phase-shift-keyed-and noncoherent frequency-shift-keyed modulations are considered. The general relationship between the probability of bit error of PN and FH systems is derived which is independent of the signal modulation and distribution of users. The degradation of the communication system performance (average probability of bit error) of the desired link as a function of the total number of interfering users within the considered area is investigated. The analysis shows that the mutual interference problem is less severe with users employing synchronous FH than with the other spread spectrum techniques. The comparison between asynchronous FH and PN is highly dependent on the relative location of interferers to the desired link and the time duty factor of the hopping.

Resonant optoacoustic cells for trace gas analysis

Abstract: An analysis of the ultimate detectivity of ideal optoacoustic cells, based on viscous gas equations, gives rigorous expressions for both signal and noise for a one-dimensional optoacoustic cell. Choice of boundary conditions for the noise calculations is dictated by the dissipation fluctuation theorem. Results of noise equivalent power calculations indicate superior performances near dc frequencies over those obtained at resonant conditions. A simplifying dissipative acoustic transmission line model describing optoacoustic cells of quite general geometric configurations is developed that is particularly useful for noise evaluation. In contrast to ideal cells, current optoacoustic cells’ detectivities are practically limited by interfering signals induced by windows’ absorption of infrared radiation; acoustical resonant conditions can help reduce such interference. A resonant optoacoustic cell exhibiting high immunity to windows interference is described that yields two orders of magnitude interference reduction compared with previously operated optoacoustic cells. The cell uses the longitudinal modes of a narrow open tube. Its minimum detectable concentration of ethylene in nitrogen is less than 0.3 parts in 109 for 1 Hz detection bandwidth using a 1 W, 10.5326 μm CO2 laser beam. Electronic noise limits the detectivity, and is ~15 dB higher than the expected Brownian noise of an ideal cell of the same configuration. Measurements with flowing trace gas are given.

Semiconductor integrated circuit device in which difficulties caused by parasitic transistors are eliminated

Abstract: A semiconductor integrated circuit device comprising a CMOS circuit in which parasitic transistors form a parasitic thyristor circuit. In this device, noise absorption resistances are provided at the noise inputs to absorb noise which otherwise might become trigger pulses for the thyristors.

Toward the Energy Resolution Limit of Mercuric Iodide in Room Temperature Low Energy X-Ray Spectrometry

Abstract: Development of mercuric iodide nuclear detectors fabricated from vapor grown single crystals continues with emphasis in our work on their capabilities as room temperature operable low-energy X-ray spectrometers. The influence of trapping in the detector crystal, electronic noise and statistical fluctuations on energy resolution of the detectors are discussed. A room temperature energy resolution value of 490 eV (FWHM) has been measured for Fe-55 (with a corresponding 420 eV value of electronic noise) using a 2mm2 HgI2 detector. The K? and Ks lines of Fe-55 at 5.9 keV and 6.5 keV have been separated, to our knowledge, for the first time at room temperature. A new Fano-factor value of 0.46 has been established for mercuric iodide. In the room temperature HgI2 detector - FET preamplifier combination the latter is the largest contributor to the width of the spectral line in the low energy region. Our efforts are therefore directed toward reducing room temperature preamplifier noise. A room temperature preamplifier noise level of 360 eV (HgI2) has been attained. We are currently investigating use of low noise, low capacitance FET devices in a more optimized preamplifier configuration which should further reduce the noise value (H.E. Kern, IEEE Trans. Nucl. Sci. NS-17). Also under investigation is the effect of Peltier cooling of the input stage of the FET preamplifier.

Estimate of minimum measurable voltage in the SEM

Abstract: The minimum measurable voltage in the SEM is estimated for a voltage contrast linearization scheme with restricted- and unrestricted-aperture analysers, using approximations for the shapes of the energy distribution curves and assuming that the only significant source of noise is on the collected electrons. A similar estimate is also made for Auger electron voltage measurement schemes. A numerical example shows that the hemispherical retarding-potential analyser system (unrestricted aperture) provides the lowest measurable voltage.

1/f noise in membranes.

Abstract: The present situation of 1/f noise in the passage of ions across membranes is examined. A survey of biological and synthetic membranes is given at which a l/f frequency dependence has been observed in the spectrum of voltage or current fluctuations. Empirical relations and theories of 1/f noise in membranes are critically discussed.

Error rate predictions and measurements in the mobile radio data channel

Abstract: A method of predicting the loss in error performance in mobile radio data transmission is given in which the variation in local mean signal level (shadowing) is included as well as fading. Also, the density function of the received signal envelope is found for the case of fading and shadowing. Field measurements are reported of error rates at VHF and UHF due to vehicle ignition noise, and the distribution of errors is plotted.

Noise responsive data input apparatus and method

Abstract: A data input device for use in an electrically noisy environment incorporates a plurality of conductive strips, arranged in rows and columns, mounted on a transparent body in front of a display device. Electrical noise is induced constantly in the conductive strips. When an operator places his finger in close association with one or more of the rows and columns, the amplitude of the electrical noise on such strips changes markedly. The change in noise level is detected and used to provide an output identifying the row and/or column in the vicinity of the operator's finger.

Characterization of Frequency Stability: Uncertainty Due to the Autocorrelation of the Frequency Fluctuations

Abstract: We considered the general sampling form for the estimate of the Allan variance which is the proposed measure of frequency stability in the time domain, and we defined a variable proportional to the difference between the average fractional frequency fluctuations over the time interval ? to derive the autocorrelation coefficient of the process to which the variable belongs. Calculations of the variance of the estimated Allan variance proved that it may be convergent to its true value with infinite sample number for considered spectral densities of frequency noise. We also applied the results to estimations of frequency measurements to know the influence of the autocorrelation of the process considered. In order to obtain some direct estimates of the confidence of the estimate, distributions of the estimate were plotted by means of computer simulations, and were compared with the chi-square distribution. Those results suggested that for white-and flicker-phase noises (and white-frequency noise) we have to take into account the autocorrelation of the process, while for flicker-or random-walk-frequency noise we may regard the process as a nearly independent (and Gaussian) one.

On-Line Pseudo-Error Monitors for Digital Transmission Systems

Abstract: Pseudo-error detectors are devices which show great potential for the measurement of the bit error rate of an on-line digital communications link. They are implemented in the form of a second detector (in addition and in parallel to the traffic data bit detector) which is very perturbation-sensitive. They do not compromise the traffic handling capacity of the system. Four methods of generating the pseudo-error characteristic are described: i) shifted detection threshold; ii) intersymbol interference enhancement; iii) noise addition; iv) sampling phase offset. Practical considerations generally govern the choice of method. Experimental results of pseudo-error detector behavior in the presence of Gaussian noise show that stable characteristics can be achieved to estimate a wide range of bit error rate (BER's) in very modest time intervals. In addition, experimental results in a real complex environment consisting of a 1.544 Mbits/s T1 capacity digital link using QPSK modulation techniques, including both Gaussian and non-Gaussian perturbations, show pseudo-error detection to be reliable for the measurement of BER and for controlling channel switching.

Relative efficiency of the sequential probability ratio test in signal detection

Abstract: The relative efficiency of a sequential hypothesis test compared to a fixed sample size test is defined as the ratio of the expected sample size of the sequential test to the sample size of the fixed sample size test with the same size and power. Asymptotic behavior of the relative efficiency is studied for the detection of a constant signal in additive noise. With some regularity conditions imposed on the noise density, the asymptotic relative efficiency of the sequential probability ratio test with respect to the corresponding fixed sample size likelihood ratio test is a function of the size and the power. As the size a approaches zero and the power approaches unity, this asymptotic relative efficiency has a limiting value depending on the functional relationship of a and 1 - \beta as they approach zero. Comparison of the power functions is also studied.

Cryogenic Millimeter-Wave Receiver Using Molecular Beam Epitaxy Diodes

Abstract: A millimeter-wave cryogenic receiver has been built for the 60-90-GHz frequency band using GaAs mixer diodes prepared by molecuIar beam epitaxy (MBE). The diodes are mounted in a reduced-height image rejecting waveguide mixer which is followed by a cooled parametric amplifier at 4.5-5.0 GHz. At a temperature of 18 K the receiver has a total single-sideband (SSB) system temperature of 312 K at a frequency of 81 GHz. This is the lowest system temperature ever reported for a resistive mixer receiver. The low-noise operation of the mixer is seen to be a result of 1) the short-circuiting of the noise entering the image port and 2) an MBE mixer diode with a noise temperature which is consistent with the theoretical shot noise from the junction and the thermal noise from the series resistance.

The extraction of spectral parameters in photon-correlation spectroscopy

Abstract: This paper contains an analysis and discussion of the factors affecting the accuracy with which spectral parameters can be determined in photon-correlation spectroscopy on Gaussian-Lorentzian light using either direct, homodyne or heterodyne detection. Both weak and strong signals are considered; the dominant noise sources being photodetection and intensity-fluctuation noise respectively. Where possible theoretical analysis is compared with computer simulation. Computer simulation also enables the behaviour, under those conditions which are too complex for direct analysis, to be studied. The effects of different normalization methods is considered; existing analysis on the extraction of spectral linewidth is extended; and the accuracy with which frequency shifts can be measured in heterodyne detection is investigated. The findings are summarized in the form of operating guide-lines for obtaining the greatest accuracy in the determination of the spectral parameters.

Analysis of Intermodulation Noise in Frequency Converters by Volterra Series

Abstract: Frequency converters produce intermodulation noise in the desired signal band which may be a serious problem for communications systems using amplitude modulation. In this paper, we introduce the Volterra series with time-varying kernels to treat intermodulation in frequency converters with one two-terminal nonlinearity. The method gives exact results up to the order calculated (third order here) for any nonlinearity expressable as a power series, will treat frequency dependence in the nonlinearity as well as the terminations, and leads to a convenient algorithm for computer calculation. The mathematics provides a physical picture of intermodulation of a specific order as being produced by the modulation of lower order products through the nonlinearity. In fact, the solution for a given order of intermodulation currents or charges is the solution of a set of linear equations where the driving functions are intermodulation currents of lower order. A program has been written for the specific but important case of an abrupt junction varactor upconverter. Results for an upconverter that may be used for single-sideband operation in the common carrier microwave band show that the largest contribution to intermodulation comes from currents which are at the sum and difference frequencies of the input (IF) signal corresponding to currents above the input port in frequency and currents in the bias circuitry. This paper documents previously unpublished work (1972) done as part of the exploratory study of single-sideband modulation on long-haul microwave radio transmission.

A Binary Quantized Digital Phase Locked Loop: A Graphical Analysis

Abstract: A non-uniform sampling digital phase locked loop (DPLL), with a hard limiter as quantizer, is analyzed by a graphical method in the case of phase and frequency step inputs and no noise. The cycle slipping and the limit cycles phenomena are investigated. An upper-bound to the model gain and, consequently, to the pull-in range is obtained. Also a closed-form expression of acquisition time is derived. Moreover, using a random-walk model, the stationary phase error variance, the mean acquisition time and the mean first slip time have been evaluated. Some two channel configurations are proposed, which allow us to obtain a faster acquisition. Finally the problems relevant to the practical implementation of the loop are analyzed.

Measurements of noise produced by flow past lifting surfaces

Abstract: Wind tunnel studies have been conducted to determine the specific locations of aerodynamic noise production within the flow field about various lifting-surface configurations. The models tested included low aspect ratio shapes intended to represent aircraft flaps, a finite aspect ratio NACA 0012 wing, and a multi-element wing section consisting of a main section, a leading edge flap, and dual trailing edge flaps. Turbulence was induced on the models by surface roughness. Lift and drag were measured for the flap models. Hot-wire anemometry was used for study of the flap-model vortex roll-up. Apparent noise source distributions were measured by use of a directional microphone system, located outside the tunnel, which was scanned about the flow region to be analyzed under computer control. These distributions exhibited a diversity of pattern, suggesting that several flow processes are important to lifting-surface noise production. Speculation concerning these processes is offered.

Point‐contact Josephson mixers at 130 GHz

Abstract: The properties of point‐contact Josephson junctions operated as mixers with an external local oscillator at 130 GHz have been studied, and the results compared with predictions of the resistively shunted junction model It was found that the junction’s output noise could be within a factor of 15 of the model prediction based on the thermal‐driving noise When the coupling to the rf source was optimized, a factor of 2 discrepancy was typical The measured conversion efficiency agreed with the model, within the experimental uncertainty in the equivalent microwave circuit The best coupling was achieved in full‐height waveguide The best overall performance, measured using the hot/cold source technique, was a single sideband conversion efficiency of 030 and a mixer‐noise temperature of 180 K (both ±20%) The best junctions were made of Nb, with carefully prepared points Nonideal behavior in other junctions is ascribed to heating effects There is some evidence that junctions whose resistance exceeds a thr

1/ƒ Noise in solid state single injection diodes

Abstract: 1/ƒ noise calculations and experiments are presented for solid state single injection diodes operating in the ohmic and space-charge-limited current (SCLC) regime. Investigations are performed on diodes both with a planar and with a hemispherical geometry. In the ohmic regime the 1/ƒ voltage noise is proportional to the square of the bias voltage V for both geometrics. In the space-charge regime the 1/ƒ voltage noise is theoretically found to be proportional to V and V 3 4 for planar and hemispherical geometry, respectively. Here the current is proportional to V2 and V 3 2 , respectively. The experiment al results of 1/ƒ voltage noise are found to be in agreement with the calculations for both kinds of geometry.

Low-noise microwave bipolar transistor with sub-half-micrometer emitter width

Abstract: This paper presents details of the fabrication process and performance of an n-p-n silicon microwave bipolar transistor with emitter opening widths as small as 0.3 µm. The fabrication process involves local oxidation, ion implantation, and lateral etching techniques for emitter definition. Noise figure as low as 1.0 dB at 1.5 GHz, 2.0 dB at 4 GHz, and 3.3 d B at 6 GHz were achieved. Measured noise figures and S -parameters are shown to be in approximate agreement with modeled performance based on device structure and process parameters. Prospects for further reductions in bipolar transistor noise figures are discussed.

Narrow-band interference rejection using the complex linear prediction filter

Abstract: The properties of the complex linear prediction filter are considered as used in the prewhitening of narrow-band interference prior to detection or parameter estimation based on optimum (MMSE) linear filtering. The parameter dependence of the filter output power, gain, and frequency response is quantified through the analysis of a single narrow-band interference plus uncorrelated tap noise. It is shown how the filter aperture has its usefulness in controlling the width of the notch formed and the whitening of the rest of the spectrum while the depth of the notch formed is proportional to the inverse of the interference-to-noise ratio.

InSb charge-injection device imaging array

Abstract: InSb CID arrays, in both 1 × 32 line and 16 × 24 two-dimensional format, have been successfully fabricated via a multilayer MIS processing technique. With the 1 × 32 line arrays, two-dimensional images were generated using a scanning mirror and a computer signal-conditioning technique. In this experiment the small temperature difference of a man's face was revealed. Two-dimensional, 16 × 24 area arrays have also been demonstrated in a staring mode by displaying real time raster-scanned IR images directly on a X-Y CRT monitor. The unprocessed IR video signal produced a sharp, clearly recognizable display with no sign of blooming, and exhibited excellent operating characteristics. Theoretical analysis showed that, at low sample rates, background limited performance (BLIP) can be obtained at background photon flux levels of as low as mid-1012photons/s . cm2. The dominant noise source, in this case, is the integrated dark current shot noise. For operation at high sample rates, however, the bandwidth-dependent noise sources limit the array performance and, thus, BLIP occurs at higher background levels. The analysis has been confirmed by measured data on line arrays, resulting in good agreement between the theoretical curve and the experimental data.

Flicker noise in semiconductors: Not a true bulk effect

Abstract: From the fact that good silicon JFET’s do not have any flicker noise, it is concluded that flicker noise in semiconductors and semiconductor devices cannot be a true bulk effect. Since JFET’s have no semiconductor‐oxide interface to speak of, whereas all other semiconductor devices do, this points to the semiconductor‐oxide interface as the source of 1/f noise. This leads to the following model. The carriers are trapped and detrapped by oxide traps, and this gives rise to two distinct noise effects: density fluctuation noise that can be described by the McWhorter model and mobility fluctuation noise that could possibly be described by the Kleinpenning model. The two models might therefore ultimately be unified into a single model, and it would depend on the device under study whether one or the other noise effect would predominate.