Search results for "Noise Figure"
showing 10 items of 27 documents
A novel noise figure and gain test set for microwave devices
2002
A new instrument for the measurement of noise and gain of microwave devices is presented. It differs from the commercial ones in the accomplishment of the gain measurement and is also useful for measuring mismatched devices such as transistors, The instrument is driven via HP-IB by a PC and a user-friendly virtual panel is designed to perform all the required operations. Also included is the possibility of removing the second-stage noise contribution and correcting various sources of error (source ENR variations, temperature variations, etc.). The test set provides a very good accuracy for both matched and mismatched devices, usually limited by source ENR accuracy and step attenuator repeat…
Proposal of Up-to-Date Standards on Methods of Measuring Noise Parameters of Microwave Transistors
1994
One of the most interesting topics for microrwave community is the characterization of low-noise transistors. After so many years, the Standards suggested by IEEE in 1960 are considered obsolete by the experimenters. A new methodology is here proposed as a standard. To support this proposal, an original measuring system for the complete characterization of microwave transistors in terms of noise, gain and scattering parameters from noise figure measurements only is presented.
Comparison between complete and simplified methods for determining the microwave noise parameters of HEMTs
1994
Modem automatic noise parameter measuring systems are based on measurements of some values of F(rs ) for different values of IГs (more than four, for redundancy) realized by adjusting an admittance transformer (tuner) inserted between the noise source and the TUT mput . Such values are then manipulated by means of proper data processing techniques using eqn.( 1) [ 11. This measuring procedure is hereafter referred to as standard to point out that the old `Standards on methods of measuring noise in linear twoports´ published by the IRE Subcommittee on noise in 1960 is considered obsolete by all the experimenters.
Full characterization of low-noise HEMTs using only noise figure measurements
1993
A method for the complete characterization of microwave transistors in terms of noise, gain and scattering parameters using a computer-controlled noise figure measuring set-up only is presented. Selection of the optimum measuring conditions, all the steps of the experimental procedure, the data collecting and processing to derive all the parameters, are fully driven by an original (unpublished) software, even without the presence of an (unskilled) operator. Results are presented about the complete characterization of a series of ten pseudomorphicHEMTs in the 8-16 GHz range. The S-parameters are also compared with those measured by an ANA.
Modeling of low-noise microwave HEMTs for CAD-oriented applications
1993
The simultaneous determination of noise, gain and scattering parameters through a computer-driven noise figure measuring system allowed the rapid and accurate characterization of several samples of low noise HEMTs of the same family. From the measured parameters an equivalent circuit model representing the behavior of the typical device is extracted by means of a decomposition approach. Comparison between the model performance and the set of measured parameters of all devices are reported for the FHR 02FH (by Fujitsu). The modeling procedure is mainly oriented to the CAD of (M)MIC low noise wideband amplifiers. © 1993 John Wiley & Sons, Inc.
Cladding-Pumped Erbium/Ytterbium Co-Doped Fiber Amplifier for C-Band Operation in Optical Networks
2021
Space-division multiplexing (SDM) attracts attention to cladding-pumped optical amplifiers, but they suffer from a low pump power conversion efficiency. To address this issue, ytterbium (Yb3+) and erbium (Er3+) co-doping is considered as an effective approach. However, it changes the gain profile of Er3+-doped fiber amplifiers and induces the gain difference between optical wavelengths in the C-band, significantly limiting the effective band of the dense wavelength-division multiplexed (DWDM) system. This paper is devoted to a detailed study of a cladding-pumped Er3+/Yb3+ co-doped fiber amplifier (EYDFA) through numerical simulations aiming to identify a configuration, before assembling a s…
DC and 1/f noise characterization of cryogenically cooled pseudomorphic HEMT's
2002
Pseudomorphic (AlGaAs/InGaAs/GaAs) HEMT's have exhibited the best noise performance over the entire LF-to-microwave frequency range if compared to MESFET's and conventional GaAs HEMT's, due to either a reduced flicker noise, a lower G/R contribution and a smaller high-field diffusion noise. We have recently investigated the microwave (up to 18 GHz) noise properties of packaged pseudomorphic HEMT's from 290 K down to cryogenic temperature values. The current experimental work is aimed at extending such analysis to the LF noise range and at low temperatures. Cryogenic noise spectra (1 Hz to 100 KHz) and DC characteristics have therefore been recorded and the relevant observations on the devic…
Noise Figures of Merit of rf-SQUID-based Josephson Travelling Wave Parametric Amplifiers
2021
The characterization of the rf-SQUID-based JTWPA in terms of its noise figure and gain for different input states (Fock states or Coherent states) has been carried out. The spectral distribution of the noise temperature Tn and gain G presents a region where the amplifier has a relatively high gain with a thermal noise that can go beyond the standard quantum limit =ℏ/2 (valid only for single mode input states [44]) as shown in Fig. 3. The TWJPA is here biased in its 3WM regime and pumped at p = 12 GHz.
Langevin Approach to Understand the Noise of Microwave Transistors
2004
A Langevin approach to understand the noise of microwave devices is presented. The device is represented by its equivalent circuit with the internal noise sources included as stochastic processes. From the circuit network analysis, a stochastic integral equation for the output voltage is derived and from its power spectrum the noise figure as a function of the operating frequency is obtained. The theoretical results have been compared with experimental data obtained by the characterization of an HEMT transistor series (NE20283A, by NEC) from 6 to 18 GHz at a low noise bias point. The reported procedure exhibits good accuracy, within the typical uncertainty range of any experimental determin…
Advanced PSA Bipolar Transistors for Wireless Applications: Measurements of Scattering Parameters and Noise Figure
1994
A complete investigation on the performance of a series of double polysilicon self-aligned (PSA) bipolar transistors in terms of scattering parameters and noise figure is here reported. The devices have been characterized over the 1-4 GHz frequency range in several bias conditions to the aim of assessing the optimum bias values for the best trade-off between noise and gain performance. This is the first part of an extensive investigation currently performed on 5 families of PSA devices having different emitter configuration and size which have been manufactured by SGS-Thomson to undergo a comparative analysis on the global transistor performance.