• The Transactions of the Korean Institute of Electrical Engineers
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• v.45 no.1
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• pp.93-99
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• 1996

The formation properties and oxidation mechanism of electrochemically oxidized porous silicon(OPS) films have been studied. To examine the humidity-sensitive properties of OPS films, surface-type and bulk-type humidity sensors were fabricated. The oxidized thickness of porous silicon layer(PSL) increases with the charge supplied during electrochemical humidity sensor shows high sensitivity at high relative humidity in low temperature. The sensitivity and linearity can be improved by optimizing a porosity of PSL. (author). refs., figs.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.3
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• pp.292-299
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• 2015

An envelope elimination and restoration transmitter that uses a tri-level envelope encoding scheme is presented for improving the efficiency and linearity of the system. The proposed structure amplifies the same magnitude signal regardless of the input peak-to-average power ratio and reduces the quantization noise by spreading out the noise to the out-of-band frequency, resulting in the enhancement of power efficiency. An improved linearity is also obtained by providing a new timing mismatch calibration technique between the envelope and phase signal. Implementation in a 130 nm CMOS process, transmitter measurements on a 20-MHz long-term evolution input signal show an error vector magnitude of 3.7 % and an adjacent channel leakage ratio of 37.5 dBc at 2.13 GHz carrier frequency.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.1
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• pp.50-54
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• 2011

In this article, the linearity of single power amplifier is improved by suppress $2^{nd}$ and $3^{rd}$ harmonics at output port of high power amplifier and by cancelling of $3^{rd}$ IMD. The matching network in order to suppress harmonics consists of metamaterial like the CRLH. The $2^{nd}$ and $3^{rd}$ harmonics are suppressed over 27 dBc, respectively. A phase of generated $3^{rd}$ IMD at output of DPA (drive power amplifier) has changed in order to offset the $3^{rd}$ IMD of HPA (high power amplifier). The harmonics of the proposed PAM suppress over 6 dB than single HPA. The PAM has a 36.98 dBm of the output power, 21.6 dB of the power gain and 29.4 % of the PAE. The harmonics is a -53 dBc about PAM. This result indicate that a harmonic level is lower 20 dB than reference power amplifier.

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.40 no.6
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• pp.8-15
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• 2003

In this paper, the issue of the differential ring oscillator in designing low phase noise is linearity improvement of delay cell's load resistor. A novel differential delay cell that improves on the Maneatis load is proposed. The linearity improvement of load resistor results in lower phase noise in ring oscillator. For comparison of the phase noise characteristics, Ali Hajimiri's phase noise model is used. In order to have a low ISF(impulse sensitivity function), it is important to have a symmetry between rise time and fall time of oscillation waveform. The ISF value of ing oscillator based on the proposed delay cell is lower than that of the existing ring oscillators. Due to this result, the phase noise is improved by 2~3dBc/Hz for the same power dissipation and oscillation frequency.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.7 s.361
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• pp.29-34
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• 2007

This paper presents a novel photonic bandgap (PBG) structure for size reduction and linearity improvement in power amplifier. The proposed structure is a two-dimensional (2-D) periodic lattice patterned on a dielectric slab that does not require nonplanar fabrication process. Throughout the experi-mental results, this structure has more broad stopband and high suppression performance than conventional three cell PBG and distorted uniplanar compact-PBG (DUC-PBG). This new PBG structure can be applied with power amplifier for linearity improvement. The 3rd intermodulation distortion (IMD3) of the power amplifier using new PBG structure is -36.16 dBc for (code division multiple access) CDMA applications. Compared with power amplifier without the proposed PBG structure, improved IMD3 is -13.49 dBc.

• Journal of Korea Water Resources Association
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• v.50 no.5
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• pp.347-358
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• 2017

This study examined characteristic differences by the rainfall direction on the runoff responses. The directional characteristics of hydrological components in a basin were quantified by von Mises distribution. The runoff hydrograph was derived using the result of convolution integration of each distribution and this hydrograph was compared with GIUH model and observed data. As a result, it was found that runoff response by rainfall direction was more similar the observed rainfall-runoff data than the runoff result using GIUH model. These results implies that runoff modeling could be improved by considering directional components in hydrologic analysis. This study would be helpful to reduce uncertainties of hydrologic analysis considering a non-linearity of rainfall-runoff process by the rainfall direction.

• Journal of The Institute of Information and Telecommunication Facilities Engineering
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• v.8 no.1
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• pp.12-17
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• 2009

In this paper, We play it for the purpose of study about the power amplifier which applied DGS and adaptive bias circuit structure to general Doherty amplifier for the efficiency of a RF power amplifier and a linearity improvement in the WiBro band. As for the IMD3, 3.4dBc was improved with -26.3dBc when we did the measurement result existing Doherty power amplifier and comparison of the Doherty power amplifier which applied an adaptive bias circuit and the DGS which proposed in this paper, and the mean power efficiency verified what was increased in 37%. Also, we were able to know PAE of 36.6% with output power 34.0dBm in P1dB when magnitude of an input signal was 25.6dBm. we did 6dB back off in output P1dB in order to confirm the ACPR which was a nonlinear characteristic and measured the ACPR. we showed the -34.55dBc which was a value of -34.5dBc or below in the 4.77MHz off-set that was a transmission standard. Therefore, we were able to know that we were satisfied with a spectrum mask standard.

• Journal of IKEEE
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• v.19 no.3
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• pp.335-341
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• 2015

Recently a demand for high precision absolute position transducer is increasing in order to control thickness in steel industry. LVDT (linear variable differential transformer) is widely used to measure the absolute position in the linearly moving cylinder under poor factory environment. In this paper we implement the three phase LVDT with a high resolution of one micron and L/D (LVDT to digital) converter. First we designed U, V, and W three phase signaling using FPGA. Second a pulse output algorithm is designed for position information with A and B phase waveforms. Finally the performance is compared with previous sensors. Experiments show that the linearity deviation error is 0.009788 [mm] and the average sinusoidal THD is 0.0751%, which means 2.2% and 33% more improved result than the previous sensors respectively.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.7 no.2
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• pp.62-69
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• 2008

This paper proposes linearization technique that the linearity is improved by controlling IMD between the drive stage and the output stage. From the experimental results of W-CDMA 4FA input signal, this amplifier has ACLR of -48dBc@5MHz offset at 50W average power. Proposed linearization technique provides predistortion effect for using drive amplifier without additional circuit, which is the significant in this paper that it makes up for the weak point of analog predistortion method and feedforward method.

• Journal of the Korean Magnetics Society
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• v.15 no.1
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• pp.48-52
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• 2005

This paper describes a current sensor for precision current measurement of an electronic watt-hour meter that is going to install in houses in the future. As the current sensor is based on an cored principle (the Rogowski principle) it is not subject to usual limitations of saturation and non-linearity of general current transformers. An advantage of the developed current sensor is that non-linearity error in low current range is improved and the construction can be kept simple using an air core. We present a magnetic field analysis of the sensor using a finite-element solver. We compared the measured values versus the calculated values.