Excess Noise Ratio Research Articles

Multiplication Noise Characterization of InAlAs-APD With Heterojunction

The excess noise and ionization coefficient ratio of InAlAs avalanche photodiodes (APDs) with heterojunctions has been measured. To obtain these values accurately, we used a differential amplifier and determined the optical current at which the avalanche multiplication equals 1. These made it possible to conduct measurements on excess noise including that in the low multiplication region. Measured ionization coefficient ratios at M=10 were 0.18 and 0.17 with multiplication layer widths of 0.2 and 0.7 ?m , respectively. Excess noise was reduced with an increase in the optical input power. This tendency appeared more prominently in APDs with a thin multiplication layer.

Novel method for transmission infrared analysis of clay minerals using silicon wafer substrates

AbstractA novel method for the analysis of clay minerals using Fourier transform infrared spectroscopy is presented. Clay mineral suspensions are dried on a Si wafer substrate for transmission infrared (IR) analysis. Four natural Source Clays from the Source Clays Repository of The Clay Minerals Society, SWy-2, SAz-1, SHCa-1 and KGa-1b, as well as the synthetic hectorite, Laponite RD, were analyzed using the described method with signal to noise (s/n) ratios in excess of 100,000 for the strongly absorbing Si-O stretching frequency. Scanning electron microscopy (SEM) images show that the mineral films possess suitable uniformity and low surface roughness for transmission IR measurements that is confirmed by minimal deviations in the baseline of collected IR spectra. The IR spectra are generated and peak locations are compared to previously reported values, generated from KBr pellet and attenuated total reflectance methods.

Noise model of a reverse‐biased cold‐FET applied to the characterization of its ENR

AbstractThis paper presents a broadband‐noise circuit model for a “cold”‐FET (Vds = 0 V) with a reverse‐biased gate. The noise model includes two intrinsic uncorrelated noise‐current sources whose spectral densities are determined from measurement of the device's S parameters and noise powers. The model is used to characterize the device's excess noise ratio (ENR) for application to full receiver‐noise calibration. Experimental results up to 40 GHz are given. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 40: 326–330, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11370

Extraction of an avalanche diode noise model for its application as an on‐wafer noise source

AbstractThis paper presents a method to characterize the excess noise ratio (ENR) of an unmatched avalanche noise diode for application as an on‐wafer noise source. It is based on the determination of a broadband device noise circuit‐model from its measured reflection coefficient and noise powers. Measured ENR is used to calibrated a noise receiver up to 40 GHz. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 38: 89–92, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10979

A novel on-wafer resistive noise source

We describe a novel on-wafer resistive noise source (ORNS) suitable for noise parameter characterization of microwave devices using the cold noise power measurement technique. The noise source can enhance measurement accuracy by providing a calibrated noise temperature directly at the device reference plane. A procedure to determine the excess noise ratio of the noise source is presented. Noise figure measurements performed up to 40 GHz with the on-wafer noise source and with a commercial coaxial noise source are in good agreement, thereby validating the technique. The novel source is effective as a noise standard up to millimeter-wave frequencies.

A set of waveguide primary thermal noise standards and related calibration systems for the frequency range 8.2-40 GHz

The national metrology laboratory, BNM-LCIE, France, has developed a set of four new waveguide primary thermal noise standards for the frequency band from 8.2 GHz to 40 GHz. Each noise standard is made with silicon carbide microwave absorber and inserted into a section of waveguide made in platinum 10% rhodium; the whole is put inside an electrical oven. The output noise temperature range of the standards obtained from temperature and attenuation measurements is within 948-1012 K/spl plusmn/1.21.8 K, in one standard-type uncertainty. The calibration of gas discharge noise sources and/or solid-state noise sources is achieved by comparison to standards using a switching radiometer. The excess noise ratio given is within 15.35-15.65 dB for gas discharge sources and within 14-16 dB for solid-state sources, with typical uncertainty of 0.02 dB.

An enhanced on-wafer millimeter-wave noise parameter measurement system

A novel on-wafer resistive noise source, useful for noise characterization of microwave devices with the cold noise power measurement technique, is described. The noise source enhances measurement accuracy by providing a calibrated noise temperature directly at the device reference plane. A procedure for determining the excess noise ratio of the noise source is presented and validated up to 40 GHz. The noise source is employed in an on-wafer measurement system, allowing the noise parameters of two-port devices to be extracted. Following a description of the apparatus and measurement procedure, an example of a high-electron-mobility transistor noise parameter measurement at millimeter-wave frequencies is presented.

Characterization and applications of on-wafer diode noise sources

A set of wafer-probable diode noise source transfer standards are characterized using on-wafer noise-temperature methods developed at the National Institute of Standards and Technology (NIST), Boulder, CO. We review the methods for accurate measurement and prediction of on-wafer noise temperature of off-wafer and on-wafer noise source standards. In analogy with the excess noise ratio (ENR) for hot noise temperatures, we introduce a representation for cold noise temperatures called the cold noise ratio (CNR), which is expressed in decibels. The ENR and CNR noise source representations share the property that the difference between off-wafer and on-wafer values may be approximated by the probe loss. We present measurements of the on-wafer ENR and reflection-coefficient information for a preliminary set of on-wafer diode transfer standards at frequencies from 8 to 12 GHz. Such transfer standards could be used in interlaboratory comparisons, as a noise calibration verification tool, as direct calibration artifacts, or as the basis for a new "noise-source probe" conceptualized here.

Microwave noise radiators

For the purposes of Microwave Active Radiometry (1), three noise radiators were developed and tested. One is a conventional noise diode source in a rectangular R-100 waveguide with a 6-dB horn attached, other two noise radiators are made as half-wave dipoles with noise diodes installed. Excess noise ratio and polarization ratio was estimated for the three designs, and the 3-D radiation pattern determined for the dipole models. For evaluation, radiometers operating at 11.5 GHz and 12.5 GHz were used, but some response was also determined with a radiometer operating at 4 GHz.

Definition, realization, and comparison of thermal noise standards

Since the state of the art for noise measurement was described in the 1967 Special Issue of PROCEEDINGS OF THE IEEE, several national standards laboratories outside the U.S. have built up thermal noise standards for the realization of the unit of noise power. Using a design for an above-ambient noise standard made of three distinct parts, a hot thermal noise standard for the waveguide band R 100 has been assembled at the Physikalisch-Technische Bundesanstalt (PTB) in Germany. This primary standard enables the calibration of the excess noise ratio (ENR) of secondary transfer standards with an accuracy of ±0.02 dB. By means of a new broad-band coaxial radiometer this value has been transferred to coaxial systems with almost the same accuracy.

The Impact of Microprocessor Technology on Receiver/Amplifier Noise Measurement

Until recently, receiver noise parameters (noise figure, effective input noise temperature, operating noise temperature) have been measured using classically analog instruments. Certain characteristics of these instruments require the user to do some "off-line" manipulation of the data in order to obtain an accurate, fully corrected result. These calculations involve. corrections for image response, second-stage noise, and reference (cold) temperature; noise generator excess noise ratio variations with frequency; loss compensation; and, conversion to other noise parameters. Since one facet of a microprocessor is data manipulation, it lends itself to "on-line" calculation and potential time savings when applied to noise parameter instrumentation.

Current noise in surface layer integrated resistors

The excess noise ratio n−1, defined as the excess noise intensity over the thermal noise intensity, is used as a parameter for characterizing the current noise of integrated resistors. Theoretically n−1 is proportional to the square of the device current, inversely proportional to the square of the device width, and independent of the device length. This is well verified by experiment. The noise spectrum is of the form 1 ƒ α with α practically equal to unity, as expected for flicker noise. The effect of current crowding near the current-carrying contacts is investigated.

A Combined Stopped Flow Temperature Jump Apparatus With Dual Beam Detection

ABSTRACT Construction of a combined stopped flow temperature jump apparatus using spectrophotometric detection is described. A dual beam ratio technique tracks and compensates for fluctuations in the lamp source. Improvements in electronic circuits, in conjunction with a cell design based on a concentric flow arrangement, has resulted in a highly sensitive detection capability with signal to noise ratios in excess of 104, so that temperature jumps as small as 1°C can be followed.

Zener-diode noise generators

Zener diodes operated in the breakdown region have been investigated as transfer noise standards in the r.f. region. A close correlation has been found between the variation in excess noise ratio (e.n.r., dB) and the temperature coefficient of Zener diodes. In particular, diodes having zero temperature coefficient of voltage also have zero temperature coefficient of e.n.r.

Apparent Frequency Dependence of the Microwave Power Radiated from Gas Discharge Noise Sources (Correspondence)

Historically it has been assumed that the microwave power per unit bandwidth radiated from the plasma of typical argon and neon gas discharge noise sources is frequency independent. There are now both a priori basis and experimental evidence for questioning this assumption. For such frequency independence to exist over a frequency range of 100 MHz to 100 GHz the following conditions must be met: (1) /spl planck/ /spl omega/ / kT<<1; (2) proper matching of the discharge to the guide; (3) an appropriate level of absorptivity of the plasma for these frequencies; (4) a Maxwellian electron velocity distribution function; and (5) absence of collective oscillations. The first three conditions are shown to be met. The fourth condition involves the concept of a radiation temperature. Because the appropriate electron velocity distributions are not Maxwellian this radiation temperature does depend somewhat on frequency. This dependence is limited to a small region around the electron-atom collision frequency. For the discharges of concern it is shown that these collision frequencies are 10/sup 9/ to 10/sup 10/s/sup -1/ and therefore contained in the frequency range of interest. The fifth condition relates to the fourth and recently has been shown in theory to be untrue. Finally there is now available experimental evidence which appears to show a small (0.2-0.3 dB) variation of excess noise ratio with frequency on existing tubes. Suggestions for future experiments and interim considerations are made.

Measurement of Effective Temperatures of Microwave Noise Sources

This report describes a system now in operation for the purpose of calibrating microwave noise sources at three selected frequencies in the range 8.2 to 12.4 Gc. Included are a discussion of the reference standard noise source, an error analysis of the standard source and the comparison system, and evidence of system performance. Results of measurements indicate that the excess noise ratio of a specific commercial argon filled noise source is 15.6 db at 9.8 Gc. A calibration service is now available for tube-in-mount noise sources at the three selected frequencies 9.0 Gc, 9.8 Gc, and 11.2 Gc.

Data on the Temperature Dependence of X-Band Fluorescent Lamp Noise Sources

This paper is concerned primarily with the performance of fluorescent lamps as microwave noise sources at 9,000 mc. In particular, it deals with the temperature dependence of the excess noise ratio of an 8-watt lamp running at a lamp current of 150 ma in a 10° E-plane holder. It was found that 1) the bulb temperature is much higher than that with a lamp current of 75 ma encountered in the 90° H-plane circuit investigated previously at 4,000 mc, hence the temperature coefficient of excess noise versus waveguide temperature obtained in the 4,000 mc circuit does not apply, 2) anomalous and unreproducible inversions in the temperature coefficient at these higher bulb temperatures have been observed, 3) these anomalies can be avoided by operating the bulb at lower temperatures, 40°C to 50°C, where the lamps appear to be just as uniform and stable and probably just as noisy as they are at 4,000 mc.

Ultrashort electromagnetic waves VI — Reception

Mr. Trevor deals with the reception of ultrashort electromagnetic waves over line-of-sight paths under practical conditions. He shows that, when directive antennas are employed, there is an optimum antenna height for which the direct and reflected rays are received in phase producing maximum effect. The concept of excess-noise ratio is developed which evaluates the merit of a receiver in a manner independent of band width, receiver impedance, signal-generator impedance, or frequency. This is the concluding article in a series of six on ultrashort electromagnetic waves. The material contained in these articles was originally presented as a series of lectures before the basic science group of the New York Section at Columbia University. A consolidated reprint will be available (see announcement elsewhere in this issue). PAUL C. CROMWELL, Chairman, Symposium Committee (College of Engineering, New York University, New York 53, N. Y.)