• Proceedings of the KIEE Conference
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• 1992.07a
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• pp.311-313
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• 1992

Automated analysis of EEG invariably requires the inclusion of a signal conditioning filter. This paper investigates the EEG waveform distortions caused by the transient responses of the various types of signal conditioning filters. This study explicitly simulates the filter responses to the typical EEG waveform models, and compares the distortions.

• Journal of Sensor Science and Technology
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• v.19 no.3
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• pp.230-237
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• 2010

In sensor signal conditioning and processing, offset and drift characteristics of an operational amplifier are an important factor when the amplifier is used for a precise sensor signal amplifier. In order to use it in high accuracy, an expensive trimming or a complex compensation circuit is required. This paper presents the improved sensor signal conditioning and processing device for ubiquitous sensor network(USN) application or general purpose by developing a hardware of the circuit for reducing the offset voltage and drift characteristics, and a software for its control and sensor signal processing. We realize better offset voltage and drift characteristics of the signal conditioning circuit using low cost operational amplifiers. The experimental results show that this technique is effective in improving the performance of the sensor signal processing device.

• Bulletin of the Korean Space Science Society
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• 2004.10b
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• pp.337-340
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• 2004

Upper stage telemetry system of KSLV- I (Korea Space Launch Vehicle I) is composed of MDU (Master Data Unit), RDU (Remote Data Unit), SRU (Shock Recorder Unit) and Transmitter. RDU is the front-end telemetry data acquisition unit which gathers analog/discrete signals from various sensors and other units, and transmits the processed data to MDU via MIL-STD-I553B data bus. In order to acquire useful data from analog signal, signal conditioning circuits, such as anti-aliasing or amplifying, should be implemented. For this purpose, SCM (Signal Conditioning Module) had been developed. This paper describes hardware structure of SCM and analog signal conditioning circuits for various sensors. Also, sampling time scheme for different sampling rates were designed and tested.

• Journal of Sensor Science and Technology
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• v.5 no.6
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• pp.25-34
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• 1996

In this paper, we have designed signal conditioning circuitry for piezoresistive pressure sensor. Signal conditioning circuitry consists of voltage reference circuit for sensor driving voltage and instrument amplifier for sensor signal amplification. Signal conditioning circuitry is simulated using HSPICE in a single poly double metal $1.5\;{\mu}m$ BiCMOS technology. Simulation results of band-gap reference circuit showed that temperature coefficient of $21\;ppm/^{\circ}C$ at the temperature range of $0\;{\sim}\;70^{\circ}C$ and PSRR of 80 dB. Simulation results of BiCMOS amplifier showed that dc voltage gain, offset voltage, CMRR, CMR and PSRR are outperformed to CMOS and Bipolar, but power dissipation and noise voltage were more improved in CMOS than BiCMOS and Bipolar. Designed signal conditioning circuitry showed high input impedance, low offset and good CMRR, therefore, it is possible to apply sensor and instrument signal conditioning circuitry.

• Journal of Sensor Science and Technology
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• v.26 no.5
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• pp.331-337
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• 2017

A readout circuit for a tactile sensor pad based on force sensing resistors was proposed, which was composed of an analog signal conditioning circuit and a digital circuit with a microcontroller. The conventional signal conditioning circuit has a dc offset voltage in the output signal, which results from the reference voltage applied to the FSR devices. The offset voltage reduces the dynamic range of the circuit and makes it difficult to operate the circuit under a low voltage power supply. In the proposed signal conditioning circuit, the dc offset voltage was removed completely. The microcontroller with A/D converter and D/A converter was used to enlarge the measurement range of pressure. For this, the microcontroller adjusts the FSR reference voltage according to the resistance magnitude of FSR under pressure. The operation of the proposed readout circuit which was connected to a tactile sensor pad with $5{\times}10$ FSR array was verified experimentally. The experimental results show the proposed readout circuit has the wider measurement range of pressure than the conventional circuit. The proposed circuit is suitable for low voltage and low power applications.

• KIEE International Transactions on Electrophysics and Applications
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• v.2C no.5
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• pp.262-267
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• 2002

In this paper, we first studied the factors affecting the motor current (MC) signal, which was strongly affected by the systematic hardware noises depending on polishing such as pad conditioning and arm oscillation of platen and recipe, head motor. Next, we studied the end point detection (EPD) for the chemical mechanical polishing (CMP) process of shallow trench isolation (STI) with reverse moat structure. The MC signal showed a high amplitude peak in the fore part caused by the reverse meal. pattern. We also found that the EP could not be detected properly and reproducibly due to the pad conditioning effect, especially when conventional low selectivity slurry was used. Even when there was no pad conditioning effect, the EPD method could not be applied, since the measured end points were always the same due to the characteristics of the reverse moat structure with an open nitride layer.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.31-32
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• 2006

A signal conditioning circuit for capacitive sensors was developed using a commercial single chip solution. Since capacitive displacement sensors can achieve high resolution and linearity, they have been widely used as precision sensors within the range of several hundred micrometers. However, they inherently have a limitation in low frequency range and some nonlinearity characteristics and so a specially designed signal conditioning circuit is needed to handle these properties. Up to now, several companies already have succeeded in the development of the capacitive sensors system and they are commercially available in the market. In this research, to construct the signal processing circuits more easily and simply, we used a universal LVDT signal conditioner (AD698). Since the AD698 provides one chip solution for a basic signal processing including modulation and demodulation using various internal components, we can build the processing circuits successfully with minimal additional circuits: a compensation circuits for the drift caused by the bias current of OP amplifiers and a fine adjustment circuit for the elimination of nonlinearity. The signal processing circuits shows nonlinearity less than 0.05% in the comparison with a laser interferometer.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.66 no.2
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• pp.82-87
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• 2017

This paper presents performance improvement of CO gas sensor signal conditioner for early fire warning system. The warning system is based on the CO sensor and its advanced signal conditioning modules network that employ electochemical gas sensor. The electochemical has advantage of having a linear output and operating with a low consumption and fast response. This electrochemical gas sensor contains a gas membrane and three electrodes(working, counter, reference electrode) in contact with an electrolyte. To use a three-electrode sensor, a voltage has to be applied between the working and the reference electrode according to the specification of the sensor. In this paper, we designed these requirements that should be considered in temperature compensation algorithm and electrode measurement of CO sensor modules by using advanced signal conditioning method included 3-electrode. Simulation and experimental results show that signal conditioner of CO sensor module using 3-electrode have a advantage linearity, sensitivity and stability, fast response etc..

• Journal of the Korean Society for Precision Engineering
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• v.24 no.9
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• pp.60-67
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• 2007

A signal conditioning circuit for capacitive displacement sensors was developed using a high frequency modulation/demodulation method, and its performance was evaluated. Since capacitive displacement sensors can achieve high resolution and linearity, they have been widely used as precision sensors within the range of several hundred micrometers. However, they inherently have a limitation in low frequency range and some nonlinearity characteristics and so a specially designed signal conditioning circuit is needed to handle these properties. The developed signal processing circuit consists of three parts: linearization, modulation/demodulation, and nonlinearity compensation. Each part was constructed discretely using several IC chips and passive elements. An evaluation system for precision displacement sensors was developed using a laser interferometer, a precision stage, and a PID position controller. The signal processing circuit was tested using the evaluation system in the respect of resolution, repeatability, linearity, and so on. From the experimental results, we know that a highly linear voltage output can be obtained successfully, which is proportional to displacement and the nonlinearity of output is less than 0.02% of full range. However, in the future, further investigation is required to reduce noise level and phase delay due to a low-pass filter. The evaluation system also can be applied effectively to calibration and evaluation of precision sensors and stages.

• The Journal of the Acoustical Society of Korea
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• v.9 no.3
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• pp.31-41
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• 1990

It is difficult to detect such flaws as stress-corrosion cracking or corrossion wastage(loss of bolt diameter) in the threads. In many cases the critical size of a flaw is very small(1-2mm order). This paper describes how it is possible to discriminate small flaw indications in threads using the time difference of thread signals [TDTS] by a signal-conditioning technique.