• The Transactions of The Korean Institute of Electrical Engineers
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• v.62 no.12
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• pp.1798-1802
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• 2013

We present a technique for measuring low resistance ranges of a decade resistor with a 4-Terminal connection. With the technique the accuracy of 0.8 % was obtained for a 1 $m{\Omega}$ resistance of the decade resistor. We suggested a proper pattern 4-Terminal measurement results with several 4-Terminal pattern and adapters. Additionally, we should that precise measurements for low resistance can be made usung a digital multimeter(DMM) only.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.11
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• pp.503-507
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• 2005

Both ratio error and phase angle error in voltage transformer(VT) depend on values of VT burden used. Thus, precise measurement of burden is very important for the evaluation of VT. A method of evaluation for VT burden has been developed by employing the portable decade resistor, with AC-DC resistance difference less than 10-3. The burden value(value and power factor) can be obtained by conductance and susceptance, obtained by measuring the change of ratio error and phase angle error caused by the resistance change of decade resistor. The burden value and power factor obtained by the method are consistent with those obtained using power analyzer within corresponding uncertainties.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.8
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• pp.403-407
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• 2006

Standard capacitors, as like as Hamon resistor standards, of series connection/parallel connection ratio $10{\mu}F/1000{\mu}F\;and\;100{\mu}F/10000{\mu}F$ were fabricated for calibration of impedance bridges or analyzers with measuring ranges up to 1 F. The calculated correction terms to the ratio of one measured value in series connection to the value in parallel connection were evaluated to be $1.92{\times}10^{-7}$. These capacitors were designed to be used not only as 100:1 capacitance standards but also as single capacitors or decade capacitors with decade values at frequencies up to 1 kHz.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.7
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• pp.1268-1274
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• 2007

A recently developed methods for the on-site calibration of the voltage transformer (VT) comparator system have been reviewed in the paper. The method utilizes the several traveling standards consisting of the VT, the non-reactive standard resistors, the wide ratio error VT, and the decade resistors. The VT is used for the absolute evaluation of a standard VT belonging to the industry. The non-reactive standard resistor and wide ratio error VT are used for the linearity check of errors in the voltage comparator of the industry. The decade resistors are used for evaluation of a VT burden of the industry.

• ETRI Journal
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• v.31 no.5
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• pp.576-584
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• 2009

A novel tunable transconductor is presented. Input transistors operate in the triode region to achieve programmable voltage-to-current conversion. These transistors are kept in the triode region by a novel negative feedback loop which features simplicity, low voltage requirements, and high output resistance. A linearity analysis is carried out which demonstrates how the proposed transconductance tuning scheme leads to high linearity in a wide transconductance range. Measurement results for a 0.5 ${\mu}m$ CMOS implementation of the transconductor show a transconductance tuning range of more than a decade (15 ${\mu}A/V$ to 165 ${\mu}A/V$) and a total harmonic distortion of -67 dB at 1 MHz for an input of 1 Vpp and a supply voltage of 1.8 V.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.1
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• pp.40-48
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• 2000

1A novel bipolar linear transconductor and its application to operational transconductance amplifier(OTA) for low-voltage low-power signal processing is proposed. The transconductor consists of a npn differential-pair with emitter degeneration resistor and a pnp differential-pair connected to the npn differential-pair in cascade. The bias current of the pnp differential-pair is used with the output current of the npn differential-pair for wide linearity and temperature stability. The OTA consists of the linear transconductor and a translinear current cell followed by three current mirrors. The proposed transconductor has superior linearity and low-voltage low-power characteristics when compared with the conventional transconductor. The experimental results show that the transconductor with transconductance of 50 ${\mu}S$ has a linearity error of less than ${\pm}$0.06% over an input voltage range from -2V to +2V at supply voltage ${\pm}$3V. Power dissipation of the transconductor was 2.44 mW. A prototype OTA with a transconductance of 25 ${\mu}S$ has been built with bipolar transistor array. The linearity of the OTA was same as the proposed transconductor. The OTA circuit also exhibits a transconductance that is linearly dependent on a bias current varying over four decades with a sensitivity of 0.5 S/A.