Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “noise diodes”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
NASA NTRS2018

Insights into Space Solar Cell Durability Using SPICE Simulation Seeded by Current-Voltage Characteristics Parametrized Using the Lambert W Special Function

We developed and validated an automated routine for the fitting of I-V curve data to the single diode model according to an exact analytical solution. Our fitting routine was validated to show good noise immunity and high accuracy usingsimulated values from LTSPICE. We are thus able to automate parameter extraction from a dataset or arbitrary size. This parameterization allows for better simulation of performance of real cells and arrays and provides utility for a host of applications relevant to space arrays. We will use this methodology to determine the array performance of radiated cells over time, and simulate the performance of the arrays with bypass diodes and power electronics.

Solar Cell↗
NASA NTRS1979

The low-noise 115-GHz receiver on the Columbia-GISS 4-ft radio telescope

The superheterodyne millimeter-wave radiometer on the Columbia-GISS 4-ft telescope is described. This receiver uses a room-temperature Schottky diode mixer, with a resonant-ring filter as LO diplexer. The diplexer has low signal loss, efficient LO power coupling, and suppresses most of the LO noise at both sidebands. The receiver IF section has a parametric amplifier as its first stage with sufficient gain to overcome the second-stage amplifier noise. A broad-banded quarter-wave impedance transformer minimizes the mismatch between mixer and paramp. At 115 GHz, the SSB receiver noise temperature is 860 K, which is believed to be the lowest figure so far reported for a room-temperature receiver at this frequency.

Cong, H.-I.↗
DOE OSTI2020

Overview of CMOS Sensors for Future Tracking Detectors

Depleted Complementary Metal-Oxide-Semiconductor (CMOS) sensors are emerging as one of the main candidate technologies for future tracking detectors in high luminosity colliders. Their capability of integrating the sensing diode into the CMOS wafer hosting the front-end electronics allows for reduced noise and higher signal sensitivity, due to the direct collection of the sensor signal by the readout electronics. They are suitable for high radiation environments due to the possibility of applying high depletion voltage and the availability of relatively high resistivity substrates. The use of a CMOS commercial fabrication process leads to their cost reduction and allows faster construction of large area detectors. In this contribution, a general perspective of the state of the art of CMOS detectors for High Energy Physics experiments is given. The main developments carried out with regard to these devices in the framework of the CERN RD50 collaboration are summarized.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
NASA NTRS1980

Heterodyne detection of the 752.033-GHz H2O rotational absorption line

A tunable high resolution two stage heterodyne radiometer was developed for the purpose of investigating the intensity and lineshape of the 752.033 GHz rotational transition of water vapor. Single-sideband system noise temperatures of approximately 45,000 K were obtained using a sensitive GaAs Schottky diode as the first stage mixer. First local oscillator power was supplied by a CO2 laser pumped formic acid laser (761.61 GHz), generating an X-band IF signal with theoretical line center at 9.5744 GHz. Second local oscillator power was provided by means of a 3 GHz waveguide cavity filter with only 9 dB insertion loss. In absorption measurements of the H2O taken from a laboratory simulation of a high altitude rocket plume, the center frequency of the 752 GHz line was determined to within 1 MHz of the reported value. A rotational temperature 75 K, a linewidth 5 MHz and a Doppler shift 3 MHz were measured with the line-of-sight intersecting the simulated-plume axis at a distance downstream of 30 nozzle diameters. These absorption data were obtained against continuum background radiation sources at temperatures of 1175 and 300 K.

Dionne, G. F.↗
NASA NTRS2002

Development of Next Generation Lifetime PSP Imaging Systems

This paper describes a lifetime PSP system that has recently been developed using pulsed light-emitting diode (LED) lamps and a new interline transfer CCD camera technology. This system alleviates noise sources associated with lifetime PSP systems that use either flash-lamp or laser excitation sources and intensified CCD cameras for detection. Calibration curves have been acquired for a variety of PSP formulations using this system, and a validation test was recently completed in the Subsonic Aerodynamic Research Laboratory (SARL) at Wright-Patterson Air Force Base (WPAFB). In this test, global surface pressure distributions were recovered using both a standard intensity-based method and the new lifetime system. Results from the lifetime system agree both qualitatively and quantitatively with those measured using the intensity-based method. Finally, an advanced lifetime imaging technique capable of measuring temperature and pressure simultaneously is introduced and initial results are presented.

Watkins, A. Neal↗
NASA NTRS1989

Laboratory and telescope use of the NICMOS2 128 x 128 HgCdTe array

The second generation of Hubble Space Telescope (HST) instruments will include a near-infrared instrument. This choice has driven the development of near-infrared arrays to larger sizes and lower read noises. Rockwell International has delivered an array for use in the Near Infrared Camera and Multi-Object Spectrometer (NICMOS) instrument; this array has been dubbed NICMOS2. NICMOS2 is a 128x128 array of HgCdTe diodes In-bonded to a switched MOSFET readout. The readout was specifically designed for astronomical use with the HST requirement of low read noise a prime goal. These arrays use detector material which is similar to that used by Rockwell in previous arrays (e.g., HgCdTe produced on a sapphire substrate), but the NICMOS2 devices differ substantially from other 128x128 arrays produced by Rockwell in having a read noise of only 30 electrons when read out using appropriate correlated sampling. NICMOS2 has now been characterized in the laboratory, and it has been used on groundbased telescopes.

Rieke, Marcia J.↗
NASA NTRS1993

A 250 GHz planar low noise Schottky receiver

A planar quasi-optical Schottky receiver based on the quasi-integrated horn antenna has been developed and tested over the 230-280 GHz bandwidth. The receiver consists of a planar GaAs Schottky diode placed at the feed of a dipole-probe suspended on a thin dielectric membrane in an etched-pyramidal horn cavity. The diode has a 1.21 micron anode diameter and a low parasitic capacitance due to the use of an etched surface channel. The antenna-mixer results in a measured DSB conversion loss and noise temperature at 258 GHz of 7.2 dB +/- 0.5 dB and 1310 K +/- 70 K, respectively, at room temperature. The design is compatible with SIS mixers, and the low cost of fabrication and simplicity makes it ideal for submillimeter-wave imaging arrays requiring a 10-20 percent bandwidth.

Ali-Ahmad, Walid Y.↗
DOE OSTI2020

Fiber-Optic Silicon Fabry-Perot Interferometric Bolometer: The Influence of Mechanical Vibration and Magnetic Field

Plasma radiation plays an important role in the operation and control of magnetic confinement fusion and is typically measured by bolometers. Here, we study the influence of mechanical vibration and magnetic field, which are typically present in magnetic confinement fusion devices, on the performance of a fiber-optic bolometer (FOB) based on silicon Fabry-Perot interferometer (FPI) demodulated by a scanning diode laser. It is found that both the vibration and magnetic field could cause large noise due to the birefringence of the silicon FPI. To mitigate the birefringence effects, we demonstrated two effective methods: polarization maintaining FOB and polarization scrambling. We show that two methods can be effective in mitigating the effect caused by the sensor birefringence: (1) replacing the regular single-mode fiber in the FOB system with polarization-maintaining fiber and (2) using a polarization scrambler after the laser source. For both methods, no significant increase in the noise was observed in the vibration and magnetic field tests. Finally, our research highlights the importance of the polarization management for the FOB systems toward their practical applications in magnetic-confinement fusion systems.

70 PLASMA PHYSICS AND FUSION TECHNOLOGY↗
NASA NTRS1991

Integrated millimeter-wave corner-cube antennas

An integrated corner-reflector antennas has been designed, fabricated, and measured at millimeter-wave frequencies. The structure consists of a traveling-wave antenna integrated on a 1.2-micron dielectric membrane, and suspended in a longitudinal cavity etched in a silicon wafer. A novel traveling wave antenna design, the modified-bend antenna, with an antenna length of 1.2 lambda and spacing 0.96 lambda from the apex, results in a wideband input impedance centered at 140 Ohm and low cross-polarization levels. Measurements at 180-270 GHz show a well-defined pattern with low sidelobe levels, and a main-beam efficiency of 93 percent and 83 percent at 180 and 222 GHz, respectively. The monolithic approach allows the integration of a matching network and a Schottky-diode or SIS detector at the base of the antenna to yield a low-noise monolithic millimeter-wave receiver.

Gearhart, Steven S.↗
NASA NTRS1997

Solid-state Image Sensor with Focal-plane Digital Photon-counting Pixel Array

A solid-state focal-plane imaging system comprises an NxN array of high gain. low-noise unit cells. each unit cell being connected to a different one of photovoltaic detector diodes, one for each unit cell, interspersed in the array for ultra low level image detection and a plurality of digital counters coupled to the outputs of the unit cell by a multiplexer(either a separate counter for each unit cell or a row of N of counters time shared with N rows of digital counters). Each unit cell includes two self-biasing cascode amplifiers in cascade for a high charge-to-voltage conversion gain (greater than 1mV/e(-)) and an electronic switch to reset input capacitance to a reference potential in order to be able to discriminate detection of an incident photon by the photoelectron (e(-))generated in the detector diode at the input of the first cascode amplifier in order to count incident photons individually in a digital counter connected to the output of the second cascade amplifier. Reseting the input capacitance and initiating self-biasing of the amplifiers occurs every clock cycle of an integratng period to enable ultralow light level image detection by the may of photovoltaic detector diodes under such ultralow light level conditions that the photon flux will statistically provide only a single photon at a time incident on anyone detector diode during any clock cycle.

Fossum, Eric R.↗
NASA NTRS1992

All-solid-state radiometers for environmental studies to 700 GHz

We report results with an all-solid-state radiometer for measurements of the ClO molecule at 649 GHz. The project is part of a program to provide low-noise, low-weight, low-power radiometers for space operation, and special effort has been expended on the development of high-efficiency solid-state frequency multipliers and Schottky-barrier mixers with low local oscillator power requirements. The best measured system noise temperature was 1750 K with the mixer and preamplifier cooled to 77 K. The mixer diode was easily pumped into saturation, indicating that the design has excellent prospects of operating at higher frequencies - our present design goal being 1 THz. We comment on the principal design features of such systems and will report on stratospheric measurements performed with this system.

Zimmermann, Ralph↗
NASA NTRS1993

An 86-106 GHz quasi-integrated low noise Schottky receiver

An integrated planar receiver was developed and tested over the 82-112 GHz bandwidth. The quasi-integrated antenna used in the receiver has a high gain, a high Gaussian coupling efficiency, and a wide bandwidth. The novel mixer design consists of a planar GaAs Schottky diode placed at the feed of a dipole-probe suspended inside an integrated horn antenna. The diode uses an etched surface channel and a planar air bridge for reduced parasitic capacitance. At 92 GHz, the room-temperature antenna-mixer exhibits a double sideband conversion loss and noise temperature of 5.5 +/- 0.5 dB and 770 K +/- 50 K, respectively. The measured DSB conversion loss and noise temperature over a 20 GHz bandwidth (86 GHz-106 GHz) remain less than 6.2 dB +/- 0.5 dB and 1000 K +/- 50 K, respectively. The low cost of fabrication and simplicity of the design makes it ideal for millimeter- and submillimeter-wave receivers.

Ali-Ahmad, Walid Y.↗
NASA NTRS1973

Proton-radiation damage in Gunn oscillators

The irradiation effects of 22 MeV protons on the electrical characteristics of GaAs continuous-wave Gunn oscillators was studied. The radio frequency power output was reduced by 3 decibels at proton fluences in the neighborhood of 1.5 x 10 to the 12th power protons/sq cm. Conductance measurements indicate that the carrier removal rate at high electric fields remained roughly 40 percent less than at low fields. Diode efficiencies of two device groups were found to be monotonically descreasing functions of fluence. Frequency modulation noise was generally unaffected by radiation, but the magnitude of the noise in the noise power spectrum increased significantly. These effects are partially accounted for, in a qualitative fashion, by a model of electron traps having field-dependent net-carrier capture rates and various response times.

Johnson, J. W.↗
NASA NTRS1990

Fiber optic sensors IV; Proceedings of the Third European Congress on Optics, The Hague, Netherlands, Mar. 13, 14, 1990

Recent advances in fiber-optic sensor (FOS) technology are examined in reviews and reports. Sections are devoted to components for FOSs, special fibers for FOSs, interferometry, FOS applications, and sensing principles and influence. Particular attention is given to solder glass sealing technology for FOS packaging, the design of optical-fiber current sensors, pressure and temperature effects on beat length in highly birefringent optical fibers, a pressure FOS based on vibrating-quartz-crystal technology, remote sensing of flammable gases using a fluoride-fiber evanescent probe, a displacement sensor with electronically scanned white-light interferometer, the use of multimode laser diodes in low-coherence coupled-cavity interferometry, electronic speckle interferometry compensated for environmentally induced phase noise, a dual-resolution noncontact vibration and displacement sensor based on a two-wavelength source, and fiber optics in composite materials.

Kersten, Ralf T.↗
NASA NTRS1986

A superconducting tunnel junction receiver for millimeter-wave astronomy

The development and construction of an ultralow noise heterodyne receiver for millimeter wave astronomy is described along with its use for 115.3 GHz Co line observations. The receiver uses a Superconductor-Insulator-Superconductor (SIS) quasiparticle tunnel junction mixer to convert the millimeter wave signal to a microwave intermediate frequency. Experiments aimed at quantitative verification of J. R. Tucker's quantum mixer theory are studied, to see whether it could be used as the basis for the design of a practical receiver. The experimental results were in excellent agreement with the theory, assuming the three frequency approximation. Infinite available gain and negative output resistance were observed for the first time, nonclassical effects which are not seen in conventional diode mixers. Using Tucker's theory, an SIS receiver was then designed and constructed. At 115 GHz, the single sideband receiver noise temperature is 83K, the lowest ever reported in this frequency range. A CO survey toward Cygnus-X region, using this SIS receiver on the Columbia-GISS 4 ft. telescope, is also described.

Pan, S. K.↗
NASA NTRS1993

Intensities and broadening coefficients for the Q branch of the 4nu-2 - nu-1 + nu-2 (471.511/cm) band of CO2

Absolute intensities for the Q-branch of the 4nu-2 - nu-1 + nu-1/2 (20,003-11,101) band in CO2 were measured for the first time. Measurements were performed for lines Q10 to Q28, at temperatures ranging from 385 to 426 K, for pressures from 3 to 40 torr, using our long wavelength tunable diode laser spectrometer. The combination of tunable diode lasers, a White cell, and a blocked impurity band detector made it possible to obtain signal to noise ratios greater than 1000 in the 471/cm spectral region, with about 3 x 10 exp -4/cm spectral resolution. The band strength was found to be 8.6(2) x 10 exp -25 cm/molec at 296 K, and the Hermann-Wallis factor was determined. Comparison with the values listed in the HITRAN 92 data base are presented. Self-, N2- and O2-broadening coefficients were also measured.

Sirota, J. M.↗
NASA NTRS2012

Low Noise Amplifiers and Receivers for Remote Sensing

The study of atmospheric dynamics and climatology depend on accurate and frequent measurements of temperature and humidity profiles of the atmosphere. These measurements furthermore enable highly accurate measurements of ocean topography by providing total column water vapour data for radar path delay correction. The atmospheric temperature profile is characterized at the oxygen molecule absorption frequencies (60 and 118 GHz) and the humidity profile at the water molecule absorption frequencies (23 and 183 GHz). Total column measurements can be achieved by comparing measured radiometric temperatures at atmospheric window channels, such as 90, 130, and 166 GHz. The standard receiver technology for these frequencies was diode mixers with MMIC LNAs being applied at the lower frequencies. The sensitivity of millimeter wave receivers improved significantly with the introduction of the low noise 35 nm gate length InP MMIC amplifiers. We currently achieve 3 dB noise figure at 180 GHz and 2 dB noise figure at 90 GHz with our MMIC low noise amplifiers (LNAs) in room temperature. These amplifiers and the receivers we have built using them made it possible to conduct highly accurate airborne measurements campaigns from the Global Hawk unmanned aerial vehicle, develop millimeter wave internally calibrated radiometers for altimeter radar path delay correction, and build prototypes of large arrays of millimeter receivers for a geostationary interferometric sounder. We use the developed millimeter wave receivers to measure temperature and humidity profiles in the atmosphere and in hurricanes as well as to characterize the path delay error in ocean topography alitmetery.

low noise temperature↗