Noise Figure Variation Research Articles

A 1.2 V Reactive-Feedback 3.1–10.6 GHz Low-Noise Amplifier in 0.13 $\mu{\hbox {m}}$ CMOS

A 15.1 dB gain, 2.1 dB (min.) noise figure low-noise amplifier (LNA) fabricated in 0.13 mum CMOS operates across the entire 3.1-10.6 GHz ultrawideband (UWB). Noise figure variation over the band is limited to 0.43 dB. Reactive (transformer) feedback reduces the noise figure, stabilizes the gain, and sets the terminal impedances over the desired bandwidth. It also provides a means of separating ESD protection circuitry from the RF input path. Bias current-reuse limits power consumption of the 0.87mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> IC to 9 mW from a 1.2 V supply. Comparable measured results are presented from both packaged and wafer probed test samples

Gain‐clamped Raman fiber amplifier in a counter‐lasing ring‐cavity using a pair of circulators

AbstractAn all‐optical gain‐clamped Raman fiber amplifier (RFA) based on the ring‐lasing technique using a pair of circulators is demonstrated experimentally. The RFA is powered using a pair of 1465‐nm pump laser diodes, which provide a peak gain at around 1565 nm. The analyses of the gain and the noise figure are carried out using different lasing wavelengths between 1550 and 1565 nm. The gain and noise figure variations are 0.4 and 0.5 dB in the gain‐clamping range, respectively. We observe a strong influence of pump‐signal relative‐intensity noise transfer, which results in a noise‐figure penalty at the signal. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 721–724, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21455

The effect of gate leakage on the noise figure of AlGaN/GaN HEMTs

The effect of gate leakage on the noise figure of AlGaN/GaN high electron mobility transistor (HEMTs) is explored. It is shown that these devices have a sizable amount of gate leakage that cannot be ignored when measuring their noise performance. Measurements across a single sample have more than 1 dB of variation in minimum noise figure. We will show this variation is because of gate leakage. A modified van der Ziel model is used to predict this large variation and allows easy noise figure prediction of HEMT and MESFET devices.

A general and rigorous WDM receiver model targeting 10-40-Gb/s channel bit rates

We present a general and rigorously formulated dynamic receiver model aiming at 10-40-Gb/s wavelength division multiplexing (WDM) system design applications. A demultiplexing (DEMUX) characteristic with periodic transfer function has been treated in detail and it has been indicated how the model should be adjusted to take into consideration a general type of noise spectral density (NSD). The bit error ratio (BER) is evaluated accounting for the influence of non-Gaussian detected amplified spontaneous emission (ASE) noise, noise correlation between stochastic noise samples in the receiver, the gain and effective noise figure variation with wavelength of optical amplifiers, channel crosstalk, and intersymbol interference (ISI) effects caused by nonideal signal modulation, fiber dispersion, fiber nonlinearities, optical MUX, and DEMUX filtering and the impulse response of the electrical low-pass filter in the receiver. Also, the influence of shot and thermal noise is taken into account. Numerical results for the BER are presented considering a realistic 16-channel 10-Gb/s WDM system operating in the C-band using normal transmission fibers and including cascaded erbium-doped fiber amplifiers (EDFAs) with dispersion compensating fibers.

Comparative study on temperature-dependent multichannel gain and noise figure distortion for 1.48- and 0.98-μm pumped EDFAs

Temperature dependence of multichannel gain flatness and noise figure (NF) was compared for different pump wavelengths of 1.48 and 0.98 /spl mu/m on silica-based erbium-doped fiber amplifiers (EDFAs) through measurement-based numerical simulation. Owing to its temperature sensitive pump emission cross section, the 1.48-/spl mu/m pumping showed greater temperature sensitivity (maximum 0.75-dB gain flatness distortion with 0.57-dB average gain level shift, 0.3-dB NF variation for 25/spl deg/C change) than the 0.98 /spl mu/m pumping (maximum 0.5-dB gain flatness distortion with 0.015-dB average gain level shift, 0.05-dB NF variation for 25/spl deg/C change). However, it was also found that distortion ripple spectra mainly coming from the changes of signal cross sections and asymmetric gain temperature dependence necessitate compensation techniques in the EDFA link, irrespective of pump wavelength.

Proposal of low-noise amplifier utilizing resonant tunneling transistors

A low-noise amplifier utilizing the negative input resistance of resonant tunneling transistors (RTT's) is proposed. Expected features of the RTT amplifiers are: 1) negligible effect of noise sources at the output, owing to their large power gain; 2) flat variation of noise figure (NF) versus frequency, due to white spectra of noise sources at the input; and 3) a high maximum oscillation frequency (f/sub max/) (over several 100 GHz), Based on simulated DC characteristics, over 500 GHz f/sub max/ and 0.3 dB NF at 100 GHz are predicted for optimized AlGaAs/GaAs/AlGaAs resonant tunneling diodes (RTD's). In an RTT formed by coupling an FET to an optimized RTD, 0.55 dB minimum noise figure and 26 dB associated gain are predicted at 100 GHz. Also, a 1/w/sup 2/ spectrum of the input noise resistance is predicted at low frequencies.

Measured Gain Improvement Characteristics of a Space Diversity Antenna System

A two-element adaptively phased array withelement gains of 18 dB was assembled andevaluated at 136 MHz. The gain improvementof the system over that of a single element wasmeasured while tracking ATS-C. The measuredgain improvement fell within 0.5 dB ofthe theoretical maximum 90 percent of thetime, corresponding to a normalized improvementof 2.5 dB for the two-element array. Athorough analysis of the AGC weighting processused in the system was made with particularemphasis placed on the effects of gainand noise figure variations between arraychannels.

Low-frequency noise figure and its application to the measurement of certain transistor parameters

Low-frequency noise measurements are shown to provide a convenient and reasonably accurate (±10 per cent) means of measuring r'_{b}. Their application to the measurement of the factor <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</tex> in the junction law <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">p_{e} = p_{n} (e_^{qV/nkT} - 1)</tex> is also described, though the values of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</tex> obtained from noise measurements do not check accurately with the values of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">n</tex> determined by other methods. Experimental determinations of the variation of low-frequency noise figure with emitter-bias current are also presented for several transistor types. The observed behavior suggests that the principal source of <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1/f</tex> noise in low-noise transistors may be in the emitter-base transition region instead of on the base surfaces where it is placed in presently accepted noise models.

Design and calculation procedures for low-noise traveling-wave tubes

A step-by-step procedure for designing low-noise traveling-wave tubes is presented in this paper. The procedure permits the rapid calculation of the significant design parameters corresponding to the conditions for minimum noise figure. The procedure includes the use of a special transmission-line type chart which facilitates the calculations and aids in understanding the principles involved in achieving low-noise behavior. By using the chart in connection with a second procedure, noise figure variation with frequency and with the tube parameters can be predicted for arbitrary electron gun design. Measured noise figures for two X-band low-noise tubes designed essentially by these procedures agree with the theoretically predicted noise figures to within 1.5 db.

Measurements of traveling-wave tube noise figure

The general structure of the tube is shown and a brief description of the electrode disposition given. Variation of noise figure is described as a function of the first anode voltage with beam current as a parameter. The independence of current is pointed out. A plot is shown of noise figure as a function of the perveance of the cathode to first-anode region and the possible significance of the beam shape in this region is described. The variation of noise figure with frequency is described and some results are given on the effect of helix size.

Low-Noise Traveling-Wave Tubes for X-Band

The experimental results of a program of study on low-noise traveling-wave tubes for 9,000 mc are described. Tests of tubes utilizing velocity jumps for noise reduction show that a single, gradual jump upward in voltage results in the best noise reduction. The design of a tube having 11.3 db noise figure and 18 db gain at 9,000 mc is given. Curves for the variation of noise figure with magnetic field, operating voltages, and cathode temperature are presented. The experimental results obtained from measuring the noise figure of some of the tubes at different frequencies suggest an empirical modification of the simple theory.