• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.3
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• pp.207-212
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• 2013

A new CMOS voltage-bias differential LC voltage-controlled oscillator (LC-VCO) with active source degeneration is proposed. The proposed degeneration technique preserves the quality factor of the LC-tank which leads to improvement in phase noise of VCO oscillators. The proposed VCO shows the high figure of merit (FOM) with large tuning range, low power, and small chip size compared to those of conventional voltage-bias differential LC-VCO. The proposed VCO implemented in 0.18-${\mu}m$ CMOS shows the phase noise of -118 dBc/Hz at 1 MHz offset oscillating at 5.03 GHz, tuning range of 12%, occupies 0.15 $mm^2$ of chip area while dissipating 1.44 mW from 0.8 V supply.

• The Journal of the Korea institute of electronic communication sciences
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• v.11 no.11
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• pp.1053-1060
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• 2016

This paper proposes an adaptive equalizer with the digitally controlled active variable capacitor. An equalizing amplifier consists of a main amplifier and a source degeneration RC filter which is implemented using the digitally controlled active variable capacitor for area efficiency and linear loss compensation. The active capacitor changes its capacitance by the amplifier gain control, which is based on miller effect. In the simulated results, the proposed equalizer compensates the high frequency loss and extends the data eye width from 0.31 UI to 0.64 UI.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.248-251
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• 2005

To investigate the degeneration process in the intervertebral disc, a three dimensional (3D) poroelastic finite-element (FE) model was developed. Disc was modeled as two different regions, such as annulus modeled with fiber reinforced 20 node poroelastic ground matrix and nucleus having large porosity. Excess Von Mises stress in the disc element assumed to be a possible source of degeneration under compressive loading condition. Recursive calculation was continued until the desired convergence was attained by changing the permeability and porosity of those elements, which could be predicted from the previous iteration. The degenerated disc model showed that relatively small compressive stresses were generated in the nucleus elements compared to normal disc. Its distribution along the sagittal plane was matched well with a previously reported experimental result. Contrasts to this result, pore pressures in the nucleus were higher than those in the normal disc. Total stress indicated similar values for two different models. This new approach using poroelastic modeling could provide the explanation of the interaction between fluid and solid matrix in the disc during the degeneration process.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.12 s.91
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• pp.1184-1189
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• 2004

A new schematic of quadrature voltage controlled oscillator(QVCO) is designed and fabricated. To obtain quadrature characteristic and low phase noise simultaneously, two differential VCOs are forced to un in quadrature mode by using coupling amplifier with a source degeneration resistor, which is optimized to obtain quadrature accuracy with minimum phase noise degradation. The designed QVCO was fabricated in standard CMOS technology. The measured performance showed the phase noise of below -120 dBc/Hz at 1 MHEz frequency offset, tuning bandwidth of 210 MHz from 2.34 GHz to 2.55 GHz with a tuning voltage varying form 0 to 1.8 V Quadrature error of 0.5 degree and amplitude error of 0.2 dB was measured with conjunction with low-lF mixer. The fabricated QVCO requires 19 mA including 5 mA in the VCO core part fiom a 1.8 V supply.

• Animal cells and systems
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• v.12 no.4
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• pp.313-319
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• 2008

The ultrastructure of oocytes during oogenesis and oocyte degeneration associated with follicle cells in female Sinonovacula constricta(Lamarck, 1818) were investigated by electron microscope observations. Ovarian follicles are surrounded by a matrix of vesicular connective tissue cells(VCT cells). VCT cells contain large quantities of glycogen particles and several lipid droplets in their cytoplasm. It is suggested that VCT cells act as a source of nutrients for vitellogenesis during oogenesis. In early vitellogenic oocytes, several coated vesicles, which appear at the basal region of the oocyte, lead to the formation of membrane-bound vesicles via endocytosis. The uptake of nutritive materials in coated vesicles formed by endocytosis appears through the formation of coated pits on the oolemma during vitellogenesis. During the late stage of oogenesis, yolk precursors(yolk granules), mitochondria and lipid droplets are present in the cytoplasm of late vitellogenic oocytes. In particular, proteinaceous yolk granules containing several different components are intermingles and form immature yolk granules. In the mature oocyte, small immature yolk granules are intermingled and form large mature yolk granules. Vitellogenesis occurs through a process of autosynthesis, involving combined activity of the Golgi complex, mitochondria and rough endoplasmic reticulum in the cytoplasm of vitellogenic oocytes. The process of heterosynthesis is where extraovarian precursors are incorporated into oocytes by endocytosis at the basal region of early vitellogenic oocytes before the formation of the vitelline coat. Follicle cells appear to play an important role in vitellogenesis and oocyte degeneration. The functions of attached follicle cells to the oocyte during oocyte degeneration are phagocytosis and digestion of phagosomes originating from oocyte degeneration. After digestion of phagosomes, it is assumed that the function of follicle cells can permit a transfer of yolk precursors necessary for vitellogenesis and allows for the accumulation of glycogen and lipid during oocyte degeneration, which can be employed by vitellogenic oocytes. Follicle cells of S. constricta may possess a lysosomal system for induction of oocyte breakdown and might resorb phagosomes in the cytoplasm for nutrient accumulation during oocyte degeneration.

• Journal of Korea Society of Industrial Information Systems
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• v.18 no.5
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• pp.1-8
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• 2013

This paper presents a variable gain amplifier(VGA) without passive devices. This VGA employes the architecture of current feedback amplifier and variable gain can be achieved by using the GM ratios of two trans-conductance(gm) circuits. To obtain linearity and high gain, it uses current division technique and source degeneration in feedback GM circuits. Input trans-conductance(GM) circuit was biased by using a tunable voltage controller to obtain variable gain. The prototype of the VGA is designed in $0.35{\mu}m$ CMOS technology and it is operating in sub-threshold region for low power consumption. The the gain of proposed VGA is varied from 23dB to 43dB, and current consumption is $2.82{\mu}A{\sim}3{\mu}A$ at 3.3V. The area of VGA is 1$120{\mu}m{\times}100{\mu}m$.

• International Journal of Contents
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• v.2 no.1
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• pp.29-33
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• 2006

The common-source low noise amplifier(LNA) with inductive degeneration using a genetic algorithm is designed and tested for a down converter in an industrial, scientific and medical (ISM) band application and a wireless broadband internet service (WiBro). The genetic algorithm optimizes the reflection coefficients to be well matched the input and output ports between multistage transistor amplifiers, and it generates low voltage standing wave ratio as well as gain flatness of the amplifier. The stability and the gain flatness of the LNA have been improved by combining the matching circuits and the series feedback microstrip lines with inductive degeneration at common-source port. In the frequency range of ISM band and WiBro application operating at $2.3GHz{\sim}2.5GHz$, the measured power gain and maximum voltage standing wave ratio (VSWR) of the LNA are $41{\pm}0.5dB$ and 1.3, and the noise figure of the LNA is lower than 0.85dB. The above results are agreed well with the theoretical values of the amplifiers.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.30 no.4
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• pp.359-367
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• 1985

This experiment was conducted to study effect of cold water damage on some growth characters related to source and sink at reproductive growth stage in Jinan (sea level 303m). The cold water irrigation duration had irrigated 4, 8 and 12 days at panicle formation stage and reproduction division stage compared to perennial water irrigation. Cold water irrigation shortened culm length and panicle length and degree of panicle exsertion. The shortening effect appeared great at lower internodes when treated at panicle formation stage but at higher internodes when treated at reduction division stage. Cold water irrigation decreased the number of secondary branches and spikelets per panicle, and increased the number of degenerated spikelets being high degeneration when treated at panicle formation stage. Spikelet sterility and impediment of grain filling were affected by duration of cold water irrigation being great when treated at spikelet primodium differentiation stage and reduction division stage in particular. Grain weight was also reduced. Significant relationship existed between spikelets sterility, grain filling and yield. The degeneration of secondary branches and spikelets correlated with leaf area but spikelet sterility and yield with culm length, panicle length and panicle exsertion.

• Development and Reproduction
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• v.12 no.1
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• pp.41-49
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• 2008

Ultrastructural changes occurring during the course of development and degeneration of oocytes in female Ruditapes philippinarum (Adams & Reeve, 1850) are described for clams collected from Gomso Bay, Korea. During the early stages of oogenesis, desomosome-like gap junctions localized between the early vitellogenic oocyte and the follicle cells. Vitellogenesis occurs through a process of autosynthesis, involving the combined activity of the Golgi complex, mitochondria and rough endoplasmic reticulum, and heterosynthesis in which extraovarian precursors are incorporated into oocytes by endocytotic activity, involving the basal region of the early vitellogenic oocytes prior to the formation of the vitelline envelope. The follicle cells appear to play an integral role in vitellogenesis and oocyte degeneration: phagocytosis and intracellular digestion of products originating from oocyte degeneration. These functions can permit a transfer of yolk precursors necessary to vitellogenesis, and they can accumulate nutrients in the cytoplasm, as glycogen and lipids, which can be employed by the vitellogenic oocyte. During the period of oocyte degeneration, follicle cells may have lysosomal system for breakdown, and resorb various phagosomes in the cytoplasm for nutrient storage. But follicle cells probably are not the major source of yolk precursors in vitellogenesis.

• JSTS:Journal of Semiconductor Technology and Science
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• v.1 no.4
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• pp.248-252
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• 2001

A noble single-ended input, double-balanced mixer topology is proposed. The mixer incorporates the common-source amplifier input stage with inductive degeneration for impedance matching. The analysis based on simulations shows that the overall performance of the mixer is excellent and is adjustable by varying the input transistor size to give best characteristics for the given linearity specifications.