An integrated low 1/f noise and high-sensitivity CMOS instrumentation amplifier for TMR sensors

2017 ◽  
Vol 31 (08) ◽  
pp. 1750070 ◽  
Author(s):  
Zhiqiang Gao ◽  
Bo Luan ◽  
Jincai Zhao ◽  
Xiaowei Liu
Keyword(s):  
Magnetic Tunnel Junction ◽  
High Sensitivity ◽  
Wheatstone Bridge ◽  
Instrumentation Amplifier ◽  
Noise Spectral Density ◽  
Input Noise ◽  
Magnetoresistive Sensor ◽  
Chip Scale Package ◽  
Equivalent Input Noise ◽  
Dc Current

In this paper, a very low 1/f noise integrated Wheatstone bridge magnetoresistive sensor ASIC based on magnetic tunnel junction (MTJ) technology is presented for high sensitivity measurements. The present CMOS instrumentation amplifier employs the gain-boost folded-cascode structure based on the capacitive-feedback chopper-stabilized technique. By chopping both the input and the output of the amplifier, combined with MTJ magnetoresistive sensitive elements, a noise equivalent magnetoresistance 1 nT/Hz[Formula: see text] at 2 Hz, the equivalent input noise spectral density 17 nV/Hz[Formula: see text](@2Hz) is achieved. The chip-scale package of the TMR sensor and the instrumentation amplifier is only about 5 mm × 5 mm × 1 mm, while the whole DC current dissipates only 2 mA.

scholarly journals A Compact Low-Distortion Low-Power Instrumentation Amplifier

2010 ◽  
Vol 5 (1) ◽  
pp. 33-41
Author(s):  
Jader A. De Lima
Keyword(s):  
Low Frequency ◽  
Design Parameters ◽  
Instrumentation Amplifier ◽  
Cmos Process ◽  
Output Stage ◽  
Noise Spectral Density ◽  
Class Ab ◽  
Input Noise ◽  
Low Distortion ◽  
Equivalent Input Noise

A CMOS instrumentation amplifier based on a simple topology that comprises a double-input Gm-stage and a low-distortion class-AB output stage is presented. Sub-threshold design techniques are applied to attain high figures of differential-gain and rejection parameters. Analyses of input-referred noise and CMRR are comprehensively carried out and their dependence on design parameters determined. The prototype was fabricated in standard n-well CMOS process. For 5V-rail-to-rail supply and bias current of 100nA, stand-by consumption is only 16μW. Low-frequency parameters are ADM=86dB, CMRR=89.3dB, PSRR+=87dB, PSRR-=74dB. For a 6.5pF-damping capacitor, ΦM=73º and GBW=47KHz. The amplifier exhibits a THD of –64.5dB @100Hz for a 1Vpp-output swing. Input-noise spectral density is 5.2μV/ Hz @1Hz and 1.9μV/ Hz @10Hz, which gives an equivalent input-noise of 37.6μV, over 1Hz-200Hz bandwidth. This circuit may be employed for low-frequency, low-distortion signal processing, advantageously replacing the conventional 3-opamp approach for instrumentation amplifiers.

A high-resolution tunneling magneto-resistance sensor interface circuit

2017 ◽  
Vol 31 (04) ◽  
pp. 1750030 ◽  
Author(s):  
Xiangyu Li ◽  
Liang Yin ◽  
Weiping Chen ◽  
Zhiqiang Gao ◽  
Xiaowei Liu
Keyword(s):  
Band Gap ◽  
Temperature Coefficient ◽  
Low Frequency ◽  
Low Noise ◽  
Instrumentation Amplifier ◽  
Interface Circuit ◽  
Input Noise ◽  
Rejection Ratio ◽  
Equivalent Input Noise ◽  
Magneto Resistance

In this paper, a chopper instrumentation amplifier and a high-precision and low-noise CMOS band gap reference in a standard 0.5 [Formula: see text] CMOS technology for a tunneling magneto-resistance (TMR) sensor is presented. The noise characteristic of TMR sensor is an important factor in determining the performance of the sensor. In order to obtain a larger signal to noise ratio (SNR), the analog front-end chip ASIC weak signal readout circuit of the sensor includes the chopper instrumentation amplifier; the high-precision and low-noise CMOS band gap reference. In order to achieve the low noise, the chopping technique is applied in the first stage amplifier. The low-frequency flicker noise is modulated to high-frequency by chopping switch, so that the modulator has a better noise suppression performance at the low frequency. The test results of interface circuit are shown as below: At a single 5 V supply, the power dissipation is 40 mW; the equivalent offset voltage is less than 10 uV; the equivalent input noise spectral density 30 nV/Hz[Formula: see text](@10 Hz), the equivalent input noise density of magnetic is 0.03 nTHz[Formula: see text](@10 Hz); the scale factor temperature coefficient is less than 10 ppm/[Formula: see text]C, the equivalent input offset temperature coefficient is less than 70 nV/[Formula: see text]C; the gain error is less than 0.05%, the common mode rejection ratio is greater than 120 dB, the power supply rejection ratio is greater than 115 dB; the nonlinear is 0.1% FS.

scholarly journals Serial MTJ-Based TMR Sensors in Bridge Configuration for Detection of Fractured Steel Bar in Magnetic Flux Leakage Testing

Sensors ◽  
2021 ◽  
Vol 21 (2) ◽  
pp. 668
Author(s):  
Zhenhu Jin ◽  
Muhamad Arif Ihsan Mohd Noor Sam ◽  
Mikihiko Oogane ◽  
Yasuo Ando
Keyword(s):  
Magnetic Flux ◽  
High Sensitivity ◽  
Wheatstone Bridge ◽  
Low Noise ◽  
Magnetic Flux Leakage ◽  
Noise Spectral Density ◽  
Steel Bar ◽  
Lift Off ◽  
Flux Leakage ◽  
Magnetic Flux Leakage Testing

Thanks to high sensitivity, excellent scalability, and low power consumption, magnetic tunnel junction (MTJ)-based tunnel magnetoresistance (TMR) sensors have been widely implemented in various industrial fields. In nondestructive magnetic flux leakage testing, the magnetic sensor plays a significant role in the detection results. As highly sensitive sensors, integrated MTJs can suppress frequency-dependent noise and thereby decrease detectivity; therefore, serial MTJ-based sensors allow for the design of high-performance sensors to measure variations in magnetic fields. In the present work, we fabricated serial MTJ-based TMR sensors and connected them to a full Wheatstone bridge circuit. Because noise power can be suppressed by using bridge configuration, the TMR sensor with Wheatstone bridge configuration showed low noise spectral density (0.19 μV/Hz0.5) and excellent detectivity (5.29 × 10−8 Oe/Hz0.5) at a frequency of 1 Hz. Furthermore, in magnetic flux leakage testing, compared with one TMR sensor, the Wheatstone bridge TMR sensors provided a higher signal-to-noise ratio for inspection of a steel bar. The one TMR sensor system could provide a high defect signal due to its high sensitivity at low lift-off (4 cm). However, as a result of its excellent detectivity, the full Wheatstone bridge-based TMR sensor detected the defect even at high lift-off (20 cm). This suggests that the developed TMR sensor provides excellent detectivity, detecting weak field changes in magnetic flux leakage testing.

scholarly journals Pressure Sensor with New Electrical Circuit Utilizing Bipolar Junction Transistor

2021 ◽  
Author(s):  
Mikhail
Keyword(s):  
Theoretical Model ◽  
Pressure Sensor ◽  
High Sensitivity ◽  
Wheatstone Bridge ◽  
Electrical Circuit ◽  
Sensor Chip ◽  
Chip Size ◽  
Junction Transistor ◽  
Developed Pressure ◽  
P Type

High sensitivity MEMS pressure sensor chip for different ranges (1 to 60 kPa) utilizing the novel electrical circuit of piezosensitive differential amplifier with negative feedback loop (PDA-NFL) is developed. Pressure sensor chip PDA-NFL utilizes two bipolar-junction transistors (BJT) with vertical n-p-n type structure (V-NPN) and eight piezoresistors (p-type). Both theoretical model of sensor response to pressure and temperature and experimental data are presented. Data confirms the applicability of theoretical model. Introduction of the amplifier allows for decreasing chip size while keeping the same sensitivity as a chip with classic Wheatstone bridge circuit.

An Ultrafast Thin-Film Microcalorimeter with Monola Yer Sensitivity (J/m2)

1995 ◽  
Vol 398 ◽  
Author(s):  
S.L. Lai ◽  
P. Infante ◽  
G. Ramanath ◽  
L.H. Allen
Keyword(s):  
Thin Film ◽  
Heating Rate ◽  
Current Pulse ◽  
High Sensitivity ◽  
Melting Process ◽  
Thermal Mass ◽  
Calorimetric Measurements ◽  
Calorimetric Technique ◽  
Dc Current ◽  
Thin Film Membrane

ABSTRACTWe introduce a high-sensitivity (∼1 J/m2) scanning microcalorimeter that can be used to perform direct calorimetric measurements on thin film samples at ultrafast heating rate (∼104 °C/s). This novel microcalorimeter is fabricated by utilizing SiN thin-film membrane technology, resulting in dramatically reduced thermal mass of the system. Calorimetric measurements are accomplished by applying a dc-current pulse to the thin-film metal (Ni) heater which also serves as a thermometer, and monitoring the real-time voltage and current of the heater. The temperature of the system and the energy delivered to the system are then determined. This calorimetric technique has been demonstrated by measuring the melting process of thin Sn films with thickness ranging from 13 to 1000 Å, and shows potential for calorimetric probing of irreversible reactions at interfaces and surfaces, as well as transformations in nanostructured materials.

scholarly journals A 24.88 nV/√Hz Wheatstone Bridge Readout Integrated Circuit with Chopper-Stabilized Multipath Operational Amplifier

2020 ◽  
Vol 10 (1) ◽  
pp. 399 ◽  
Author(s):  
Kwonsang Han ◽  
Hyungseup Kim ◽  
Jaesung Kim ◽  
Donggeun You ◽  
Hyunwoo Heo ◽  
...  
Keyword(s):  
Integrated Circuit ◽  
Operational Amplifier ◽  
Wheatstone Bridge ◽  
Input Resistance ◽  
Cmos Technology ◽  
Low Noise ◽  
Oxide Semiconductor ◽  
Instrumentation Amplifier ◽  
Readout Integrated Circuit ◽  
Chopper Stabilization

This paper proposes a low noise readout integrated circuit (IC) with a chopper-stabilized multipath operational amplifier suitable for a Wheatstone bridge sensor. The input voltage of the readout IC changes due to a change in input resistance, and is efficiently amplified using a three-operational amplifier instrumentation amplifier (IA) structure with high input impedance and adjustable gain. Furthermore, a chopper-stabilized multipath structure is applied to the operational amplifier, and a ripple reduction loop (RRL) in the low frequency path (LFP) is employed to attenuate the ripple generated by the chopper stabilization technique. A 12-bit successive approximation register (SAR) analog-to-digital converter (ADC) is employed to convert the output voltage of the three-operational amplifier IA into digital code. The Wheatstone bridge readout IC is manufactured using a standard 0.18 µm complementary metal-oxide-semiconductor (CMOS) technology, drawing 833 µA current from a 1.8 V supply. The input range and the input referred noise are ±20 mV and 24.88 nV/√Hz, respectively.

Do Modern Hearing Aids Meet ANSI Standards?

2016 ◽  
Vol 27 (08) ◽  
pp. 619-627 ◽  
Author(s):  
Jourdan T. Holder ◽  
Erin M. Picou ◽  
Jill M. Gruenwald ◽  
Todd A. Ricketts
Keyword(s):  
Quality Control ◽  
Hearing Aids ◽  
Hearing Aid ◽  
Analysis Data ◽  
National Standards ◽  
Control Measures ◽  
Input Noise ◽  
Release Times ◽  
Quality Control Testing ◽  
Equivalent Input Noise

Background: The American National Standards Institute (ANSI) provides standards used to govern standardization of all hearing aids. If hearing aids do not meet specifications, there are potential negative implications for hearing aid users, professionals, and the industry. Recent literature has not investigated the proportion of new hearing aids in compliance with the ANSI specifications for quality control standards when they arrive in the clinic before dispensing. Purpose: The aims of this study were to determine the percentage of new hearing aids compliant with the relevant ANSI standard and to report trends in electroacoustic analysis data. Research Design: New hearing aids were evaluated for quality control via the ANSI S3.22-2009 standard. In addition, quality control of directional processing was also assessed. Study Sample: Seventy-three behind-the-ear hearing aids from four major manufacturers, that were purchased for clinical patients were evaluated before dispensing. Data Collection and Analysis: Audioscan Verifit (version 3.1) hearing instrument fitting system was used to complete electroacoustic analysis and directional processing evaluation of the hearing aids. Frye’s Fonix 8000 test box system (Fonix 8000) was also used to cross-check equivalent input noise (EIN) measurements. These measurements were then analyzed for trends across brands and specifications. Results: All of the hearing aids evaluated were found to be out of specification for at least one measure. EIN and attack and release times were the measures most frequently out of specification. EIN was found to be affected by test box isolation for two of the four brands tested. Systematic discrepancies accounted for ˜93% of the noncompliance issues, while unsystematic quality control issues accounted for the remaining 7%. Conclusions: The high number of systematic discrepancies between the data collected and the specifications published by the manufacturers suggests there are clear issues related to the specific protocols used for quality control testing. These issues present a significant barrier for hearing aid dispensers when attempting to accurately determine if a hearing aid is functioning appropriately. The significant number of unsystematic discrepancies supports the continued importance of quality control measures of new and repaired hearing aids to ensure that the device is functioning properly before it is dispensed and to avoid future negative implications of fitting a faulty device.

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