• ETRI Journal
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• v.46 no.2
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• pp.238-249
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• 2024

Equivalent-time sampling can improve measurement or sensing systems because it enables a broader frequency band and higher delay resolution for periodic signals with lower sampling rates than a Nyquist receiver. Meanwhile, a digital down-conversion (DDC) technique can be implemented using a straightforward radio frequency (RF) circuit. It avoids timing skew and in-phase/quadrature gain imbalance instead of requiring a high-speed analog-to-digital converter to sample an intermediate frequency (IF) signal. Therefore, when equivalent-time sampling and DDC techniques are combined, a significant synergy can be achieved. This study provides a parameter design methodology for optimal equivalent-time sampling using DDC.

• Transactions on Electrical and Electronic Materials
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• v.2 no.4
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• pp.1-6
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• 2001

In this paper, a 1.5 V high-gain high-frequency CMOS complementary operational amplifier is presented. The input stage of op-amp is designed for supporting the constant transconductance on the Input stage by consisting of the parallel-connected rail-to-rail complementary differential pairs. And consisting of the class-AB rail-to-rail output stage using the concept of elementary shunt stage and the grounded-gate cascode compensation technique for improving the low PSRR which was a disadvantage in the general CMOS complementary input stage, the load dependence of open loop gain and the stability of op- amp on the output load are improved, and the high-gain high-frequency operation can be achieved. The designed op-amp operates perfectly on the complementary mode with the 180° phase conversion for a 1.5 V supply voltage, and shows the DC open loop gain of 84 dB, the phase margin of 65°, and the unity gain frequency of 20 MHz. In addition, the amplifier shows the 0.1 % settling time of .179 ㎲ for the positive step and 0.154 ㎲ for the negative step on the 100 mV small-signal step, respectively, and shows the total power dissipation of 8.93 mW.

• The Transactions of the Korean Institute of Power Electronics
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• v.25 no.2
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• pp.133-141
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• 2020

The use of high-gain-voltage step-up converters for distributed power generation systems is being popularized because of the need for new energy generation and power conversion technologies. In this study, a new constructed high-gain-boost DC-DC converter was proposed to coordinate low voltage output DC sources, such as PV or fuel cell systems, with high DC bus (380 V) lines. Compared with traditional boost DC-DC converters, the proposed converter can create higher gain and has wider input voltage range and lower voltage stress for power semiconductors and passive elements. Moreover, the proposed topology produces multilevel DC voltage output, which is the main advantage of the proposed topology. Steady-state analysis in continuous conduction mode of the proposed converter is discussed in detail. The practicability of the proposed DC-DC converter is presented by experimental results with a 300 W prototype converter.

• Korean Journal of Poultry Science
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• v.25 no.1
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• pp.31-37
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• 1998

Two experiment were conducted to evaluate the feeding value of probiotics for the broiler chicks. Basal diets based on corn and soybean meal with no supplemental probiotics contained 21% dietary crude protein for the first 3 weeks and 19% for the rest of two weeks. In experiment 1, 0.2 % probiotics containing 2X 10 6 cfu /ml of Saccharomyces cerevisiae(S), Clostridium butyricum(C), Lactobacillus acidophilus(L), Bacillus polyfermenticus(B) were respectively supplemented to control groups. Two hundred day-olo chicks were randomly assigned to five treatments which had four replicates of 10 chicks each per treatment. Weight gain, feed consurnption, feed conversion ratio (FCR) were weekly measured for 5 weeks. The number of intestinal microflora was examined at the end of experiment. In experiment 1, Weight gain and feed intake of chicks fed probiotics exhibited a significant response compared to those of control for the first three weeks(P<0.01). Weight gain of S or C treatments was higher than that of control for the rest of two weeks, whereas it was significantly lower in L and B treatments than S or C treatments (P<0.01). Chicks fed S or C was significantly increased weight gain(P <0.05) compared to that of control at five weeks of age. FCR of C treatment seemed to improve relative to other supplemental probiotics groups, but was not significantly different. The number of intestinal anaerobes and Lactobacillus in large intestine of chicks fed probiotics supplements was significantly decreased compared to control groups(P<0.01). In experiment 2, there were six treatments: Ti, control; T2, 0.2%S; T3, 0.2%S + 0.2%C; T4, 0.2%S + 0.2%L; T5, 0.2%S + 0.2%B; T6, 0.2%S + 0.1%C + o.i%L + 0.1%B. Control diet based on corn soybean meal contained 21% CP and 3,2OOca1 /g ME with no probiotics. There were four replicates of 10 chicks each per treatment. Weight gain of chicks fed probiotics tended to increase compared to control groups, but were not significantly different between them. FCR was also improved in probiotics treatments. However, there were no significant differences between probiotics supplementation and control groups. The results of these experiments indicated that dietary supplemental probiotics improved weight gain, feed efficiency for the first three weeks of young broiler chicks, whereas supplementation of C, L, B combined probiotics to young broiler chicks was not superior to those of single or two probiotics.

• JSTS:Journal of Semiconductor Technology and Science
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• v.4 no.3
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• pp.168-173
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• 2004

A low power CMOS receiver baseband analog circuit based on alternating filter and gain stage is reported. For the given specifications of the baseband analog block, optimum allocation of the gain, IIP3 and NF of the each block was performed to minimize current consumption. The fully integrated receiver BBA chain is fabricated in $0.18\;{\mu}m$ CMOS technology and IIP3 of 30 dBm with a gain of 55 dB and noise figure of 31 dB are obtained at 4.86 mW power consumption.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.7
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• pp.1386-1392
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• 2009

An analysis is presented for super-high-speed optical demodulation by an avalanche photodiode(APD) with electric mixing. A normalized gain is defined to evaluate the performance of the optical mixing detection. Unlike previous work, we include the effect of the nonlinear variation of the APD capacitance with bias voltage as well as the effect of parasitic and amplifier input capacitance. As a results, the normalized gain is dependent on the signal frequency and the frequency difference between the signal and the local oscillator frequency. However, the current through the equivalent resistance of the APD is almost independent of signal frequency. The mixing output is mainly attributed to the nonlinearity of the multiplication factor. We show also that there is an optimal local oscillator voltage at which the normalized gain is maximized for a given avalanche photodiode.

• Journal of Information Display
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• v.10 no.1
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• pp.28-32
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• 2009

The correlation between the optical performance of the reflective polarizer, which is a key optical component for the brightness enhancement of the liquid crystal display (LCD), and the configuration of optical sheets was investigated in a direct-lit CCFL (cold-cathode fluorescent lamp) backlight. The optical gain of the reflective polarizer, the polarization state of the light emitted from each film, and the loss factor for the polarization conversion process occurring in the lower part of the backlight were determined using a phenomenological approach for the polarization recycling process. The present study suggests that the correlation between the optical performance of the brightness enhancement films and the backlight configuration should be carefully considered in the optimization of the backlight structure.

• Journal of Power Electronics
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• v.18 no.3
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• pp.672-680
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• 2018

A bidirectional exponential-gain switched-capacitor (SC) DC-DC converter is developed in this paper. When compared with existing exponential SC converters, the number of switches is significantly reduced and its structure is simplified. The voltage transfer features, voltage ripple across capacitors, efficiency and output impedance of the proposed converter are analyzed in detail. Optimization of the output impedance is also discussed and the best type of capacitance distribution is determined. A common function of the voltage gain to the output impedance is found among the proposed converter and other popular SC voltage multipliers. Experimental evaluation is carried out with a 6-24V bidirectional prototype converter.

• Journal of the korean Society of Automotive Engineers
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• v.13 no.5
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• pp.73-80
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• 1991

Air/fuel ratio control system for gasoline engines has been analyzed to determine the control gain of the system. In this analysis the engine is modelled to be a simple time delaying element and the ramp-and-jump method is used to control air/fuel ratio. The result shows that it is necessary to measure the air flow rate accurately to enhance the control performance. And also it is shown that the control gain must be determined in some bounded region to meet the fast dynamic response and high catalyst conversion efficiency together.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.4
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• pp.229-236
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• 2019

This study proposes a DC-DC converter topology of solid-state transformer for low-voltage DC distribution. The proposed topology consists of a voltage balancer and bipolar DC-DC converter. The voltage and current equations are obtained on the basis of switching states to design the controller. The open-loop gain of the controller is achieved using the derived voltage and current equations. The controller gain is selected through the frequency analysis of the loop gain. The inductance and capacitance are calculated considering the voltage and current ripples. The prototype is fabricated in accordance with the designed system parameters. The proposed topology and designed controller are verified through simulation and experiment.