DEDICATED INSTRUMENTATION FOR HIGH SENSITIVITY, LOW FREQUENCY NOISE MEASUREMENT SYSTEMS

2004 ◽  
Vol 04 (02) ◽  
pp. L385-L402 ◽  
Author(s):  
C. CIOFI ◽  
G. GIUSI ◽  
G. SCANDURRA ◽  
B. NERI
Keyword(s):  
Background Noise ◽  
Flicker Noise ◽  
Low Frequency ◽  
High Sensitivity ◽  
Design Guidelines ◽  
Low Noise ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Low Frequencies ◽  
Noise Measurements

Low Frequency Noise Measurements (LFNM) can be used as very sensitive tool for the characterization of the quality and the reliability of electron devices. However, especially in those cases in which the frequency range of interest extends below 1 Hz, instrumentation with an acceptable low level of background noise is not easily found on the market. In fact, at very low frequencies, the flicker noise introduced by the electronic components which make up the instrumentation becomes predominant and several interesting phenomena which could be detected by means of LFNM may result completely hidden in the background noise. This consideration is not limited to the case of input preamplifiers but does extend to any piece of instrumentation that contributes to the LFNM systems, and in particular to the power supplies used for biasing the Device Under Test. During the last few years, our research groups have been strongly involved in the design of very low noise instrumentation for application in the field of LFNM. In this work we report the main results which we have obtained together with a discussion of the design guidelines that have allowed us, in a few cases, to reach noise levels not to be equalled by any instrumentation available on the market.

scholarly journals Single JFET Front-End Amplifier for Low Frequency Noise Measurements with Cross Correlation-Based Gain Calibration

Electronics ◽  
2019 ◽  
Vol 8 (10) ◽  
pp. 1197
Author(s):  
Graziella Scandurra ◽  
Gino Giusi ◽  
Carmine Ciofi
Keyword(s):  
Background Noise ◽  
Cross Correlation ◽  
Low Frequency ◽  
Open Loop ◽  
Low Noise ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Front End ◽  
Voltage Amplifier ◽  
Noise Measurements

We propose an open loop voltage amplifier topology based on a single JFET front-end for the realization of very low noise voltage amplifiers to be used in the field of low frequency noise measurements. With respect to amplifiers based on differential input stages, a single transistor stage has, among others, the advantage of a lower background noise. Unfortunately, an open loop approach, while simplifying the realization, has the disadvantage that because of the dispersions in the characteristics of the active device, it cannot ensure that a well-defined gain be obtained by design. To address this issue, we propose to add two simple operational amplifier-based auxiliary amplifiers with known gain as part of the measurement chain and employ cross correlation for the calibration of the gain of the main amplifier. With proper data elaboration, gain calibration and actual measurements can be carried out at the same time. By using the approach we propose, we have been able to design a low noise amplifier relying on a simplified hardware and with background noise as low as 6 nV/√Hz at 200 mHz, 1.7 nV/√Hz at 1 Hz, 0.7 nV/√Hz at 10 Hz, and less than 0.6 nV/√Hz at frequencies above 100 Hz.

scholarly journals A Low-Noise and Quasi-Ideal DC Current Source Dedicated to Four-Probe Low-Frequency Noise Measurements

2020 ◽  
Vol 69 (1) ◽  
pp. 194-200 ◽  
Author(s):  
Jean-Marc Routoure ◽  
Sheng Wu ◽  
Carlo Barone ◽  
Laurence Mechin ◽  
Bruno Guillet
Keyword(s):  
Current Source ◽  
Low Frequency ◽  
Low Noise ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Noise Measurements ◽  
Dc Current

Attenuation of Earmuffs against Low Frequency Noise

1987 ◽  
Vol 6 (4) ◽  
pp. 167-174 ◽  
Author(s):  
Jukka Starck ◽  
Jussi Pekkarinen ◽  
Seppo Aatola
Keyword(s):  
Low Frequency ◽  
Peak Level ◽  
Standard Test ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Low Frequencies ◽  
Hearing Protectors ◽  
Noise Measurements ◽  
Attenuation Values ◽  
Very High

The standard test for hearing protectors cannot be applied to determine the attenuation values for low frequency noise or for noise consisting of high intensity impulses. Moreover, the aging of earmuffs and the use of spectacles may cause leakage which decreases attenuation mainly at low frequencies. To study the real attenuation of earmuffs, noise measurements were taken outside and inside the earmuffs of workers at industrial work places, and of military conscripts when shooting with different firearms. The effect of spectacles on the attenuation was measured under laboratory conditions. In industrial workplaces the average attenuation was 4 dB in the 63 and 125 Hz octave bands. For shooting noise the attenuation was found to be good for small calibre weapons but poor for large calibre weapons, which generate very high peak level impulses at low frequencies. Spectacles decreased earmuff attenuation by 9–11 dB.

Low-frequency noise correlations in lateral pnp bipolar transistors

1992 ◽  
Vol 70 (10-11) ◽  
pp. 1112-1117
Author(s):  
A. Nathan ◽  
E. Charbon ◽  
W. Kung ◽  
A. Salim
Keyword(s):  
Integrated Circuit ◽  
Low Frequency ◽  
Intrinsic Noise ◽  
Low Noise ◽  
Bipolar Transistors ◽  
Current Gain ◽  
Low Noise Amplifiers ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Low Frequencies

Measurement results of low-frequency noise behaviour, and in particular, the noise correlations in lateral pnp bipolar transistors are presented for various bias conditions in both forward active and saturation regimes. The correlation in output collector noise is very high with a value close to unity only when the device is in medium injection. At extremely high injection, the degree of coherence degrades, depicting a behaviour similar to the forward current gain of the device. This degradation can be attributed to emitter-crowding effects. The correlation in output noise can be exploited to drastically suppress the intrinsic noise, particularly at low frequencies, making such devices useful for the input stage of amplifiers; the first step towards realisation of ultra low-noise amplifiers in standard integrated circuit technology.

LOW FREQUENCY NOISE PARAMETERS IN AN AlGaN/GaN HETEROSTRUCTURE WITH 33% AND 75% Al MOLE FRACTION

2004 ◽  
Vol 14 (03) ◽  
pp. 762-768
Author(s):  
S. A. VITUSEVICH ◽  
S. V. DANYLYUK ◽  
N. KLEIN ◽  
M. V. PETRYCHUK ◽  
A. E. BELYAEV ◽  
...  
Keyword(s):  
Mole Fraction ◽  
Flicker Noise ◽  
Low Frequency ◽  
High Electron Mobility Transistor ◽  
Low Noise ◽  
Excess Noise ◽  
Frequency Noise ◽  
High Electron ◽  
Low Frequency Noise ◽  
Non Linear

Transport and low frequency noise properties of undoped AlGaN/GaN high electron mobility transistor (HEMT) heterostructures with 33% and 75% Al mole fractions in the ohmic and non-linear regimes of applied voltages are studied. In contrast to the low Al mole fraction, the noise properties of 75 % content structures are not affected by passivation. At small voltages both kinds of structures demonstrate about the same level of l/f excess noise. Deviations from conventional flicker noise were observed at high applied voltages. Additionally, differences in noise behaviour between the two structures were revealed. In the 75% content structures, a noise level suppression was registered in the non-linear regime, which is important for the development of low noise oscillator circuits.

An Investigation into the Microstructure of the Low Frequency Auditory Threshold and of the Loudness Function in the near Threshold Region

1987 ◽  
Vol 6 (1) ◽  
pp. 34-39 ◽  
Author(s):  
Graham P. Frost
Keyword(s):  
Subjective Effects ◽  
Low Frequency ◽  
Frequency Noise ◽  
Threshold Region ◽  
Low Frequency Noise ◽  
Sound Perception ◽  
Low Frequencies ◽  
Auditory Thresholds ◽  
Noise Measurements ◽  
Near Threshold

The minimum audible field (MAF) is the sound pressure level at the threshold of audibility. The MAF threshold contour clearly demonstrates the variations in sensitivity of the auditory system with frequency. This frequency dependent sensitivity is also apparent at higher intensities, the importance of which is demonstrated by the extensive use of the dB(A) weighting in noise measurements. The sparse data available on low frequency auditory thresholds, and on the subjective effects of low level low frequency noise in the threshold region, indicated that a study of low frequency thresholds and near threshold equal loudness contours would fill a significant gap in the understanding of sound perception in this frequency range. This investigation demonstrates the existence of wide variations in individual sensitivity to low frequency sound. The diversity in auditory response to low frequencies between individuals should therefore be a prime consideration in low frequency noise control.

scholarly journals A Chopper-Embedded BGR Composite Noise Reduction Circuit for Clock Generator

Electronics ◽  
2021 ◽  
Vol 10 (18) ◽  
pp. 2257
Author(s):  
Neeru Agarwal ◽  
Neeraj Agarwal ◽  
Chih-Wen Lu ◽  
Masahito Oh-e
Keyword(s):  
Flicker Noise ◽  
Noise Analysis ◽  
Low Frequency ◽  
Low Noise ◽  
Frequency Noise ◽  
Clock Generator ◽  
Low Frequency Noise ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Offset Voltage

A chopper-embedded bandgap reference (BGR) scheme is presented using 0.18 μm CMOS technology for low-frequency noise suppression in the clock generator application. As biasing circuitry produce significant flicker noise, along with thermal noise from passive components, the proposed low-noise chopper-stabilized BGR circuit was designed and implemented for wide temperature range of −40 to 125 °C, including a startup and self-biasing circuit to reduce critical low-frequency noise from the bias circuitry and op amp input offset voltage. The BGR circuit generated a reference voltage of 1.25 V for a supply voltage range of 2.5–3.3 V. The gain of the implemented BGR operational transconductance amplifier is 84.1 dB. A non-overlapping clock circuit was implemented to reduce the clock skew effect, which is also one of the noise contributors. The noise analysis of a chopped bandgap voltage reference was evaluated through cadence periodic steady-state (PSS) analysis and periodic noise (PNoise) analysis. The low-frequency flicker noise was reduced from 1.5 to 0.4 μV/sqrt(Hz) at 1 KHz, with the proposed chopping scheme in the bandgap. Comparisons of the noise performance of the chopper-embedded BGR, with and without a low-pass filter, were also performed, and the results show a further reduction in the overall noise. A reduction in the flicker noise, from 181.3 to 10.26 mV/sqrt(Hz) at 100 KHz, was observed with the filter. All circuit blocks of the proposed BGR scheme were designed and simulated using the EDA tool HSPICE, and layout generation was carried out by Laker. The BGR architecture layout dimensions are 285.25 μm × 125.38 μm.

scholarly journals Measurement of Noise in Supercapacitors

2017 ◽  
Vol 24 (4) ◽  
pp. 645-652 ◽  
Author(s):  
Arkadiusz Szewczyk
Keyword(s):  
Flicker Noise ◽  
Low Frequency ◽  
Frequency Noise ◽  
Data Recording ◽  
Low Frequency Noise ◽  
Noise Measurements ◽  
Noise Data ◽  
Assess Quality

AbstractA developed method and measurement setup for measurement of noise generated in a supercapacitor is presented. The requirements for noise data recording are considered and correlated with working modes of supercapacitors. An example of results of low-frequency noise measurements in commercially available supercapacitors are presented. The ability of flicker noise measurements suggests that they can be used to assess quality of tested supercapacitors.

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