Variable Bandwidth Chopper Amplifier for Eddy-Current Non-Destructive Testing

被引：0

作者：

Silva, Joao ^{[1
]}

Oliveira, David ^{[1
]}

Caetano, Diogo M. ^{[1
]}

Rabuske, Taimur ^{[1
]}

Fernandes, Jorge ^{[1
]}

机构：

[1] Univ Lisbon, Inst Super Tecn, INESC ID, Lisbon, Portugal

来源：

ELECTROMAGNETIC NONDESTRUCTIVE EVALUATION (XX) | 2017年 / 42卷

关键词：

NDT; Eddy Currents; Magneto Resistors; TMR; TMJ; Low-Noise; Chopper; Pseudo Resistor;

D O I：

10.3233/978-1-61499-767-2-187

中图分类号：

TM [电工技术]; TN [电子技术、通信技术];

学科分类号：

0808 ; 0809 ;

摘要：

This work focuses on an amplifier to be integrated in an Eddy Current (EC) Non-Destructive Testing (NDT) system presented in [1]. This system is designed for detection of superficial and internal flaws on conductive materials, using magnetoresistive (MR) sensors. The sensors can be biased with a DC+AC current to allow signal heterodyning. Biasing signal is analogically removed without the use of any digital circuit. Minimum working frequency is 1.5 Hz, allowing larger penetration depths. At such low frequencies, the amplifier presents large flicker (or 1/f) noise, which is mitigated using Chopper Stabilization [2]. The amplifier rejects DC and has a controllable pole frequency that can be tuned from 1.5 Hz to 1 Mhz. This tunability is achieved by implementing a novel tunable pseudo-resistor, to reduce large settling times when changing between sensors. The amplifier has a 12 nV/root Hz at 10 Hz with flicker corner frequency at 10 kHz and a noise floor of 4 nV/root Hz. Simulations were performed in AMS 0.35 mu m CMOS technology.

引用

页码：187 / 194

页数：8

共 5 条

[1]

Caetano D. M., 2014, 11 EUR C NONDESTRUCT, P1

[2]

Djekic D, 2016, IEEE INT SYMP CIRC S, P842, DOI 10.1109/ISCAS.2016.7527372

[3] Circuit techniques for reducing the effects of op-amp imperfections: Autozeroing, correlated double sampling, and chopper stabilization [J].