Self-noise spectra for 34 common electromagnetic seismometer/preamplifier pairs

1994 ◽  
Vol 84 (1) ◽  
pp. 222-228
Author(s):  
Peter W. Rodgers
Keyword(s):  
Operational Amplifier ◽  
Low Noise ◽  
The Self ◽  
Noise Model ◽  
Op Amp ◽  
Op Amps ◽  
At Resonance ◽  
Amplitude Density ◽  
Noise Spectra

Abstract Because of a lack of such information, computed self-noise spectra are presented for a total of 34 frequently used electromagnetic-seismometer/preamplifier combinations. For convenience, most of these data are given in three sets of units. Peterson's Low Noise Model is included on each plot for comparison. The self noises of nine frequently employed electromagnetic seismometers properly matched to their operational amplifier (op-amp) preamplifiers are plotted. In terms of amplitude density spectra in (m/sec**2)/Hz**0.5, the values of the self-noise spectra at resonance range from a low of 3 × 10−10 for the GS-13 to a high of 1.3 × 10−8 for the HS-1. Between these two seismometers, in order of increasing noise at resonance, are the SV-1, SL-210V, S-13, SS-1, L-4C, S-6000CD, and the L-22D. To show which seismometers exhibit the lowest noise with which operational amplifier preamplifiers, the self noises of the HS-1, L-22D, L-4C, GS-13, SV-1, and SL-210V are plotted each paired with four commonly used op-amps: the LT1028, OP-227, OP-77, and the LT1012. For the GS-13, the LT1012 was the quietest. For the rest, the OP-227 was the best. For a given seismometer, the differences in self noise between op-amps were frequently a factor of 2 or 3, and as large as 10 in one case. The use of these op-amps in the analog front ends of five current digital seismic recorders is discussed.

Frequency limits for seismometers as determined from signal-to-noise ratios. Part 1. The electromagnetic seismometer

1992 ◽  
Vol 82 (2) ◽  
pp. 1071-1098 ◽  
Author(s):  
Peter W. Rodgers
Keyword(s):  
Operational Amplifier ◽  
Seismic Noise ◽  
Low Noise ◽  
Noise Model ◽  
Noise Voltage ◽  
Signal To Noise ◽  
Noise Current ◽  
System Noise ◽  
Large Gain ◽  
Total Noise

Abstract The range of frequencies that a seismometer can record is nominally set by the corner frequencies of its amplitude frequency response. In recording pre-event noise in very quiet seismic sites, the internally generated self-noise of the seismometer can put further limits on the range of frequencies that can be recorded. Some examples of such low seismic noise sites are Lajitas, Texas; Deep Springs, California; and Karkaralinsk, U.S.S.R. In such sites, the seismometer self-noise can be large enough to degrade the signal-to-noise ratio (SNR) of the recorded pre-event data. The widely used low seismic noise model (LNM) (due to Peterson, 1982; Peterson and Hutt, 1982; Peterson and Tilgner, 1985; Peterson and Hutt, 1989) is used as representative of the input ground motion acceleration power density spectrum (pds) at such very low noise sites. This study determines the range of frequencies for which the SNR of an electromagnetic seismometer exceeds 3 db (a factor of 2 in power and 1.414 in amplitude). In order to do this, an analytic expression is developed for the SNR of a generalized electromagnetic seismometer. The signal pds using Peterson's LNM as an input is developed for an electromagnetic seismometer. Suspension noise is modeled following Usher (1973). In order to determine the electronically caused component of the self-noise, noise properties are compared among three commonly used amplifiers. The advantages and disadvantages of the inverting and noninverting configurations in terms of their SNR are discussed. In most cases, the noninverting configuration is to be preferred as it avoids the use of the large gain setting resistances required in the inverting configuration to avoid loading the seismometer output. A noise model is developed for a typical low noise operational amplifier (Precision Monolithics OP-27). This noise model is used to numerically compute the SNRs for the three electromagnetic seismometers used as examples. The degradation in SNR caused by large gain setting resistances is shown. Numerical examples are given using the Mark Products L-4C and L-22D and the Teledyne Geotech GS-13 electromagnetic seismometers. For each of the example seismometers, the calculated range of frequencies for which their SNR exceeds 3 db is as follows: the GS-13, 0.078 to 56.1 Hz; the L-4C, 0.113 to 7.2 Hz; and the L-22D, 0.175 to 0.6 Hz. For the GS-13, the calculated lower and upper frequencies at which the SNR is 3 db are 0.078 and 56.1 Hz. This compares with the values 0.073 and 59 Hz measured in the noise tests on the vertical GS-13. Expressions for the total noise voltage referred to the input of an operational amplifier are developed in Appendix A. It is shown that in the inverting configuration, although no noise current flows in the input resistor, the noise current appears in the expression for the total noise voltage as if it did. In Appendix B, it is shown that any noise current flowing through an electromagnetic seismometer having a generator greater than several hundred V/m/sec generates a back emf that adds significantly to the noise of the system. This implies that system noise tests that substitute a resistor at the noninverting input of the preamplifier or clamp the seismometer mass will tend to underestimate the system noise.

scholarly journals Intelligent GA optimizer for single supply operational amplifier and MMIC low noise amplifier

2014 ◽  
Vol 10 (1) ◽  
Author(s):  
Neoh Siew Chin ◽  
Izatul Syafina Ishak ◽  
Lim Wei Jer ◽  
Arjuna Marzuki
Keyword(s):  
Circuit Design ◽  
Operational Amplifier ◽  
Low Noise ◽  
Low Noise Amplifier ◽  
Multi Objective ◽  
Op Amp ◽  
Optimization Study ◽  
Noise Amplifier ◽  
5 Ghz ◽  
Single Objective

Single-Supply Operational Amplifier (Op-Amp) is important to the applications on battery-powered equipments whereas MMIC Low Noise Amplifier (LNA) is a type of integrated circuit device used in capturing operating signal in microwave frequency. This paper presents an optimization study of a Single-Supply Op-Amp and a MMIC LNA using Genetic Algorithm (GA). GA is proposed to optimize multiple input variables so as to achieve the required circuit design outputs. In Single-Supply Op-Amp, a single objective GA optimization study is conducted. Based on the single objective circuit design justification, GA is further investigated for its capability to deal with multiple design objectives in 5 GHz MMIC LNA. In this research, the Single-Supply Op-Amp design is synthesized via LTSpice whereas the MMIC LNA design is simulated through Agilent Advanced Design System (ADS). The optimization performance of GA for both single and multi-objective circuit designs is studied and the developed multi-objective GA optimizer is further compared with ADS built-in optimizers of Gradient and Quasi-Newton respectively. From the results, GA is shown to be capable in optimizing both single objective Op-Amp and multi-objective LNA.

The ‘Dozen-Impedance’ Operational Amplifier Module for Experimentation

1989 ◽  
Vol 26 (3) ◽  
pp. 224-232 ◽  
Author(s):  
L. O. Kehinde
Keyword(s):  
Transfer Function ◽  
Operational Amplifier ◽  
Laboratory Experiments ◽  
Op Amp ◽  
Op Amps

This paper presents a ‘dozen-impedance’ op. amp. configuration that can be used for a myriad laboratory experiments on op. amps. From the generated transfer function, a new formalized statement is presented from which the transfer function of op. amp. circuits that fall under this class can be obtained without the rigours of earlier well-known matrix techniques. Some experimental configurations are suggested.

A Low Noise Operational Amplifier Design Using Chopper Stability

2013 ◽  
Vol 562-565 ◽  
pp. 1450-1454
Author(s):  
Xiao Wei Liu ◽  
Liang Liu ◽  
Jian Yang ◽  
Song Chen ◽  
Wei Ping Chen
Keyword(s):  
Operational Amplifier ◽  
Low Frequency ◽  
Low Noise ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Op Amp ◽  
Chopper Stabilization ◽  
Amplifier Design

Noise has become a significant bottleneck limiting the performance of the op amp, and chopper stabilization technology [1] is commonly used to reduce the noise of the op amp. The chopper stabilization technology can significantly reduce the low-frequency 1/f noise of op amp, then reducing the total low-frequency noise of op amp. In this paper, we designed a chopper-stabilized low-noise op amp, and used Cadence software for simulation and debugging.

Improvement of Gain Accuracy and CMRR of Low Power Instrumentation Amplifier Using High Gain Operational Amplifiers

2020 ◽  
Vol 12 (3) ◽  
pp. 168-174
Author(s):  
Rashmi Sahu ◽  
Maitraiyee Konar ◽  
Sudip Kundu
Keyword(s):  
Low Power ◽  
Building Blocks ◽  
High Gain ◽  
The Other ◽  
Operational Amplifiers ◽  
Instrumentation Amplifier ◽  
Biomedical Signals ◽  
Op Amp ◽  
Op Amps ◽  
Multi Stage

Background: Sensing of biomedical signals is crucial for monitoring of various health conditions. These signals have a very low amplitude (in μV) and a small frequency range (<500 Hz). In the presence of various common-mode interferences, biomedical signals are difficult to detect. Instrumentation amplifiers (INAs) are usually preferred to detect these signals due to their high commonmode rejection ratio (CMRR). Gain accuracy and CMRR are two important parameters associated with any INA. This article, therefore, focuses on the improvement of the gain accuracy and CMRR of a low power INA topology. Objective: The objective of this article is to achieve high gain accuracy and CMRR of low power INA by having high gain operational amplifiers (Op-Amps), which are the building blocks of the INAs. Methods: For the implementation of the Op-Amps and the INAs, the Cadence Virtuoso tool was used. All the designs and implementation were realized in 0.18 μm CMOS technology. Results: Three different Op-Amp topologies namely single-stage differential Op-Amp, folded cascode Op-Amp, and multi-stage Op-Amp were implemented. Using these Op-Amp topologies separately, three Op-Amp-based INAs were realized and compared. The INA designed using the high gain multistage Op-Amp topology of low-frequency gain of 123.89 dB achieves a CMRR of 164.1 dB, with the INA’s gain accuracy as good as 99%, which is the best when compared to the other two INAs realized using the other two Op-Amp topologies implemented. Conclusion: Using very high gain Op-Amps as the building blocks of the INA improves the gain accuracy of the INA and enhances the CMRR of the INA. The three Op-Amp-based INA designed with the multi-stage Op-Amps shows state-of-the-art characteristics as its gain accuracy is 99% and CMRR is as high as 164.1 dB. The power consumed by this INA is 29.25 μW by operating on a power supply of ±0.9V. This makes this INA highly suitable for low power measurement applications.

scholarly journals A Four-Channel Low-Noise Readout IC for Air Flow Measurement Using Hot Wire Anemometer in 0.18 μm CMOS Technology

Sensors ◽  
2021 ◽  
Vol 21 (14) ◽  
pp. 4694
Author(s):  
Kyeongsik Nam ◽  
Hyungseup Kim ◽  
Yongsu Kwon ◽  
Gyuri Choi ◽  
Taeyup Kim ◽  
...  
Keyword(s):  
Supply Voltage ◽  
Air Flow ◽  
Low Noise ◽  
Cmos Process ◽  
Significant Information ◽  
Flow Measurements ◽  
Pass Filter ◽  
Low Pass Filter ◽  
Op Amp ◽  
Noise Characteristics

Air flow measurements provide significant information required for understanding the characteristics of insect movement. This study proposes a four-channel low-noise readout integrated circuit (IC) in order to measure air flow (air velocity), which can be beneficial to insect biomimetic robot systems that have been studied recently. Instrumentation amplifiers (IAs) with low-noise characteristics in readout ICs are essential because the air flow of an insect’s movement, which is electrically converted using a microelectromechanical systems (MEMS) sensor, generally produces a small signal. The fundamental architecture employed in the readout IC is a three op amp IA, and it accomplishes low-noise characteristics by chopping. Moreover, the readout IC has a four-channel input structure and implements an automatic offset calibration loop (AOCL) for input offset correction. The AOCL based on the binary search logic adjusts the output offset by controlling the input voltage bias generated by the R-2R digital-to-analog converter (DAC). The electrically converted air flow signal is amplified using a three op amp IA, which is passed through a low-pass filter (LPF) for ripple rejection that is generated by chopping, and converted to a digital code by a 12-bit successive approximation register (SAR) analog-to-digital converter (ADC). Furthermore, the readout IC contains a low-dropout (LDO) regulator that enables the supply voltage to drive digital circuits, and a serial peripheral interface (SPI) for digital communication. The readout IC is designed with a 0.18 μm CMOS process and the current consumption is 1.886 mA at 3.3 V supply voltage. The IC has an active area of 6.78 mm2 and input-referred noise (IRN) characteristics of 95.4 nV/√Hz at 1 Hz.

A Low-noise Low-offset Op Amp in 0.35μm CMOS Process

2006 ◽  
Author(s):  
Zhineng Zhu ◽  
R. Tumati ◽  
S. Collins ◽  
R. Smith ◽  
D.E. Kotecki
Keyword(s):  
Low Noise ◽  
Cmos Process ◽  
Op Amp ◽  
Low Offset

scholarly journals Performance Evaluation of a Resonant-integrated Pumping System

2018 ◽  
Vol 202 ◽  
pp. 02009
Author(s):  
Vincent Chieng-Chen Lee
Keyword(s):  
Performance Evaluation ◽  
Excitation Frequency ◽  
Pressure Head ◽  
Low Noise ◽  
Integrated System ◽  
Positive Outcomes ◽  
Pumping System ◽  
At Resonance ◽  
Impedance Pump ◽  
Maximum Amplification

Impedance pump is a simple valve-less pumping mechanism; it offers a low energy, low noise alternative at both macro- and micro-scale devices. It is also demonstrated to be a promising new technique for producing and amplifying net flow. There have been research studying the effects of series-connected impedance pump, where an increase in net flow is exhibited. In this study, an integrated system of conventional pump and impedance pump is introduced. This paper describes the performance evaluation of this integrated pumping system, with emphasis on the amount of amplification induced as a function of Womersley number (normalized excitation frequency) and normalized pressure head. Due to the nature of the resonant valve-less impedance pump, the integrated pumping system exhibits similar behaviour and characteristics as an impedance pump, such as the pulsatile nature of net flow. Results show positive outcomes where maximum amplification of 91.7% is demonstrated at resonance.

Radiation modes of propeller tonal noise

2021 ◽  
pp. 1-25
Author(s):  
Hanbo Jiang ◽  
Siyang Zhong ◽  
Han Wu ◽  
Xin Zhang ◽  
Xun Huang ◽  
...  
Keyword(s):  
Spherical Harmonics ◽  
Sound Field ◽  
Low Noise ◽  
Noise Model ◽  
Sound Waves ◽  
Tonal Noise ◽  
Noise Sources ◽  
Separate Source ◽  
Radial Forces ◽  
Flow Variables

Abstract This paper focuses on the radiation modes and efficiency of propeller tonal noise. The thickness noise and loading noise model of propellers has been formulated in spherical coordinates, thereby simplifying numerical evaluation of the integral noise source. More importantly, the radiation field can be decomposed and projected to spherical harmonics, which can separate source-observer positions and enable an analysis of sound field structures. Thanks to the parity of spherical harmonics, the proposed model can mathematically explain the fact that thrusts only produce antisymmetric sound waves with respect to the rotating plane. In addition, the symmetric components of the noise field can be attributed to the thickness, as well as drags and radial forces acting on the propeller surface. The radiation efficiency of each mode decays rapidly as noise sources approach the rotating centre, suggesting the radial distribution of aerodynamic loadings should be carefully designed for low-noise propellers. The noise prediction model has been successfully applied to a drone propeller and achieved a reliable agreement with experimental measurements. The flow variables employed as an input of the noise computation were obtained with computational fluid dynamics (CFD), and the experimental data were measured in an anechoic chamber.

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