The testing technology of low noise chopper amplifier

2014 ◽  
pp. 323-328
Keyword(s):  
Low Noise ◽  
Testing Technology ◽  
Chopper Amplifier

Three-Dimensional Micro-Displacement Control System for a Conductor Defect Detection System

2012 ◽  
Vol 588-589 ◽  
pp. 1431-1436 ◽  
Author(s):  
San Sheng Wang ◽  
Liu Bin Fan ◽  
Gong Chen ◽  
Tong He
Keyword(s):  
Magnetic Field ◽  
Control System ◽  
Detection System ◽  
Three Dimensional ◽  
Sample Surface ◽  
Low Noise ◽  
Central Processor ◽  
Displacement Control ◽  
Destructive Testing ◽  
Testing Technology

This paper proposes a method to detect conductor defects in the field of modern non-destructive testing technology. A self-magnetic field induced by flowing current in the conductor is used in the detection technique, and a three-dimensional micro-displacement stage platform is used to scan the sample surface to obtain the self-magnetic field mapping of the whole sample. The subsequent data processing and imaging technology of the detection signal is also developed. To achieve precise positioning of the triaxial directions, an STM32 microcontroller (MCU) is used as the central processor to design the displacement control system, which communicates with a PC computer through the MCU system. The experimental results demonstrate that the stepper motor driving the magnetic sensor could run uniformly and that the proposed system has the advantages of smooth motion, low noise and high precision. As a consequence, the micro-displacement control system can be used to get a clear mapping of the defects in the sample.

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.

A Monolithic CMOS-MEMS 3-Axis Accelerometer With a Low-Noise, Low-Power Dual-Chopper Amplifier

2008 ◽  
Vol 8 (9) ◽  
pp. 1511-1518 ◽  
Author(s):  
Hongwei Qu ◽  
Deyou Fang ◽  
Huikai Xie
Keyword(s):  
Low Power ◽  
Low Noise ◽  
Cmos Mems ◽  
Chopper Amplifier
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