Compact Readout Electronics for 62-Channel DROS Magnetocardiogram System

Kim, Jin–Mok; Lee, Yongho; Kim, Ki Woong; Kwon, Hyuk‐Chan; Park, Yong-Ki; Sasada, Ichiro

doi:10.1109/tasc.2005.849982

Cited by 8 publications

(3 citation statements)

References 7 publications

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“…An Agilent 35670A spectrum analyzer was used for noise evaluation. Note that for each measurement, the sensor signal was amplified using a specially designed low-noise preamplifier [ 46 ]. In this experimental environment, the amplifier exhibited a white noise level of 1

with a gain of 60 dB.…”

Section: Methodsmentioning

confidence: 99%

Bridge Resistance Compensation for Noise Reduction in a Self-Balanced PHMR Sensor

Lee

Jeon

et al. 2021

Sensors

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Advanced microelectromechanical system (MEMS) magnetic field sensor applications demand ultra-high detectivity down to the low magnetic fields. To enhance the detection limit of the magnetic sensor, a resistance compensator integrated self-balanced bridge type sensor was devised for low-frequency noise reduction in the frequency range of 0.5 Hz to 200 Hz. The self-balanced bridge sensor was a NiFe (10 nm)/IrMn (10 nm) bilayer structure in the framework of planar Hall magnetoresistance (PHMR) technology. The proposed resistance compensator integrated with a self-bridge sensor architecture presented a compact and cheaper alternative to marketable MEMS MR sensors, adjusting the offset voltage compensation at the wafer level, and led to substantial improvement in the sensor noise level. Moreover, the sensor noise components of electronic and magnetic origin were identified by measuring the sensor noise spectral density as a function of temperature and operating power. The lowest achievable noise in this device architecture was estimated at ~3.34 nV/Hz at 100 Hz.

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with a gain of 60 dB.…”

Section: Methodsmentioning

confidence: 99%

Bridge Resistance Compensation for Noise Reduction in a Self-Balanced PHMR Sensor

Lee

Jeon

et al. 2021

Sensors

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show abstract

“…For noise characterization, the sensor current was applied along the magnetic easy axis using a Keithley 2400 Current Source Meter. The sensor signal was amplified by a custom-made low-noise preamplifier [ 58 ] and sampled by a 16-bit ADC model (35670A Keysight FFT Dynamic signal analyzer) with a sampling rate of 512 Hz. Temperature dependence of noise measurements was performed in both CC and CV modes at different sensing currents.…”

Section: Methodsmentioning

confidence: 99%

Operational Parameters for Sub-Nano Tesla Field Resolution of PHMR Sensors in Harsh Environments

Jeon

Das

Kim

et al. 2021

Sensors

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The resolution of planar-Hall magnetoresistive (PHMR) sensors was investigated in the frequency range from 0.5 Hz to 200 Hz in terms of its sensitivity, average noise level, and detectivity. Analysis of the sensor sensitivity and voltage noise response was performed by varying operational parameters such as sensor geometrical architectures, sensor configurations, sensing currents, and temperature. All the measurements of PHMR sensors were carried out under both constant current (CC) and constant voltage (CV) modes. In the present study, Barkhausen noise was revealed in 1/f noise component and found less significant in the PHMR sensor configuration. Under measured noise spectral density at optimized conditions, the best magnetic field detectivity was achieved better than 550 pT/√Hz at 100 Hz and close to 1.1 nT/√Hz at 10 Hz for a tri-layer multi-ring PHMR sensor in an unshielded environment. Furthermore, the promising feasibility and possible routes for further improvement of the sensor resolution are discussed.

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“…The digital pulses were transmitted through fibre-optic cables. Each FLL PCB has a size of 45 mm × 95 mm; the FLL circuits and digital interface circuits are assembled as shown in figure 2 [14]. Figure 3 shows a block diagram of the measurement system.…”

Section: Readout and Control Electronics For Squid Operationmentioning

confidence: 99%

64-channel magnetocardiogram system based on double relaxation oscillation SQUID planar gradiometers

Lee¹,

Kim²,

Kim³

et al. 2006

Supercond. Sci. Technol.

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We developed a magnetocardiogram (MCG) system measuring tangential field components using planar gradiometers. The SQUID insert has 64 planar gradiometers, of which 32 measure the x-component and the other 32 measure the y-component, where the chest surface is in the x and y plane. The SQUID sensor is a double relaxation oscillation SQUID type with high flux-to-voltage transfers. Thus, a room-temperature dc preamplifier with a modest input voltage noise could be used to detect the SQUID output voltage directly. The pickup coils are first-order planar gradiometers with a baseline of 4 cm, and they were connected to the input coils using a superconductive bonding of Nb wires. The sensor coverage area of the 64 channels is 190 mm in diameter, and the average boil-off rate of liquid He is 3.6 L/d in everyday operation of the SQUID system. The SQUID operation of the 64 channels was done by digital controls and the average noise of the MCG system was 4.6 fT Hz −1/2 at 100 Hz, inside a magnetically shielded room.

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Compact Readout Electronics for 62-Channel DROS Magnetocardiogram System

Cited by 8 publications

References 7 publications

Bridge Resistance Compensation for Noise Reduction in a Self-Balanced PHMR Sensor

Bridge Resistance Compensation for Noise Reduction in a Self-Balanced PHMR Sensor

Operational Parameters for Sub-Nano Tesla Field Resolution of PHMR Sensors in Harsh Environments

64-channel magnetocardiogram system based on double relaxation oscillation SQUID planar gradiometers

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