scholarly journals A Low-Noise Chopper Amplifier with Offset and Low-Frequency Noise Compensation DC Servo Loop

Electronics ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 1797
Author(s):  
Yuekai Liu ◽  
Zhijun Zhou ◽  
Yixin Zhou ◽  
Wenyuan Li ◽  
Zhigong Wang
Keyword(s):  
Frequency Band ◽  
Low Frequency ◽  
Low Noise ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Neural Signals ◽  
Noise Compensation ◽  
Front End ◽  
Servo Loop ◽  
Chopper Amplifier

The low-frequency and low-amplitude characteristics of neural signals poses challenges to neural signals recording. A low noise amplifier (LNA) plays an important role in the recording front-end. A chopper-stabilized analog front-end amplifier (FEA) for neural signal acquisition is presented in this paper. It solves the noise and offset interference caused by the servo loop in the chopper amplifier structure. The proposed FEA employs a switched-capacitor (SC) integrator with offset and low-frequency noise compensation. Moreover, a dc-blocking impedance is placed for ripple-rejection (RR), and a positive feedback loop is employed to increase input impedance. The proposed circuit is design in a 0.18-µm 1.8-V CMOS process. It achieves a bandwidth of up to 9 kHz for local field potential and action potential signals acquisition. The referred-to-input (RTI) noise is 0.72 µVrms in the 1 Hz~200 Hz frequency band and 3.46 µVrms in the 200 Hz~5 kHz frequency band. The noise effect factor is 0.43 (1 Hz~200 Hz) and 2.08 (200 Hz~5 kHz). CMRR higher than 87 dB and PSRR higher than 85 dB are achieved in the entire pass-band. It consumes a power of 3.96 µW/channel and occupies an area of 0.244 mm2/channel.

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 Low-Frequency Noise Evaluation on a Commercial Magnetoimpedance Sensor at Submillihertz Frequencies for Space Magnetic Field Detection

Sensors ◽  
2019 ◽  
Vol 19 (22) ◽  
pp. 4888
Author(s):  
Tao Wang ◽  
Chen Kang ◽  
Guozhi Chai
Keyword(s):  
Magnetic Field ◽  
Low Frequency ◽  
Temperature Stability ◽  
Space Missions ◽  
Low Noise ◽  
Integration Time ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Field Detection ◽  
Measurement Limit

The purpose of this study was to measure the low-frequency noise and basic performance of a commercial magnetoimpedance (MI) sensor at sub-millihertz frequencies for use in space missions. Normally, space missions require measuring very weak magnetic fields with a long integration time, such as the space gravitational wave detection mission requiring sub-millihertz frequencies. We set up a platform for measuring the performance on this MI sensor, including low-frequency noise, measurement limit, linearity, and temperature stability. The results show that the low-frequency noise of the MI sensor is below 10 nT/√Hz at 1 mHz and below 100 nT/√Hz at 0.1 mHz; its measurement limit is 600 pT. The MI sensor is characterized by high precision, small size, and low noise, demonstrating considerable potential for application in magnetically sensitive experiments requiring long integration time. This is an effect way to solve the problem that there is on one suitable magnetic sensor at space magnetic field detection, but the sensor requires improvements in temperature stability.

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

scholarly journals Noise Measurements Of Resistors With The Use Of Dual-Phase Virtual Lock-In Technique

2015 ◽  
Vol 22 (4) ◽  
pp. 503-512
Author(s):  
Adam Witold Stadler ◽  
Andrzej Kolek ◽  
Zbigniew Zawiślak ◽  
Andrzej Dziedzic
Keyword(s):  
Noise Suppression ◽  
Excitation Frequency ◽  
Low Frequency ◽  
Noise Signal ◽  
Low Noise ◽  
Frequency Noise ◽  
Dual Phase ◽  
Low Frequency Noise ◽  
Electronic Components ◽  
Lock In

Abstract Measurement of low-frequency noise properties of modern electronic components is a very demanding challenge due to the low magnitude of a noise signal and the limit of a dissipated power. In such a case, an ac technique with a lock-in amplifier or the use of a low-noise transformer as the first stage in the signal path are common approaches. A software dual-phase virtual lock-in (VLI) technique has been developed and tested in low-frequency noise studies of electronic components. VLI means that phase-sensitive detection is processed by a software layer rather than by an expensive hardware lock-in amplifier. The VLI method has been tested in exploration of noise in polymer thick-film resistors. Analysis of the obtained noise spectra of voltage fluctuations confirmed that the 1/f noise caused by resistance fluctuations is the dominant one. The calculated value of the parameter describing the noise intensity of a resistive material, C = 1·10−21 m3, is consistent with that obtained with the use of a dc method. On the other hand, it has been observed that the spectra of (excitation independent) resistance noise contain a 1/f component whose intensity depends on the excitation frequency. The phenomenon has been explained by means of noise suppression by impedances of the measurement circuit, giving an excellent agreement with the experimental data.

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.

scholarly journals Virtual instruments in low-frequency noise spectroscopy experiments

2015 ◽  
Vol 28 (1) ◽  
pp. 17-28
Author(s):  
Adam Stadler ◽  
Andrzej Dziedzic
Keyword(s):  
Thick Film ◽  
Virtual Instrument ◽  
Low Frequency ◽  
Low Noise ◽  
Frequency Noise ◽  
Low Frequency Noise ◽  
Noise Sources ◽  
Noise Component ◽  
Noise Spectroscopy ◽  
Noise Map

Low-frequency noise spectroscopy (LFNS) is an experimental technique to study noise spectra, typically below 10 kHz, as a function of temperature. Results of LFNS may be presented as the ?so-called? noise maps, giving a detailed insight into fluctuating phenomena in electronic devices and materials. The authors show the usefulness of virtual instrument concept in developing and controlling the measurement setup for LFNS experiments. An example of a noise map obtained for polymer thick-film resistors (PTFRs), made of commercial compositions, for temperature range 77 K - 300 K has been shown. The experiments proved that 1/f noise caused by resistance fluctuations is the dominant noise component in the studied samples. However, the obtained noise map revealed also thermally activated noise sources. Furthermore, parameters describing noise properties of resistive materials and components have been introduced and calculated using data from LFNS. The results of the work may be useful for comparison of noise properties of different resistive materials, giving also directions for improvement of thick-film technology in order to manufacture reliable, low-noise and stable PTFRs.

Sign in / Sign up

Export Citation Format

Share Document