• Title/Summary/Keyword: Impedance Transformer

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Design of Doherty Amplifier With Push-Pull Structure Using BALUN Transform (발룬을 이용한 푸쉬풀 구조의 도허티 증폭기 설계)

  • 정형태;김성욱;장익수
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.41 no.4
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    • pp.51-58
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    • 2004
  • Push-pull structure with balun transformer is presented for load modulation technique which improves the overall efficiency of power amplifier Under the assumption that output impedance of fumed-off amplifier is high, conventional Doherty amplifier is composed of impedance inverter and peaking amplifier, of which operation is controlled by the input power level. In many case, however, impedance of 'off'amplifier is very low due to matching network or parasitic output capacitance. This paper introduces novel load modulation technique which uses low output impedance of 'off'amplifier. Experimental results show that good linearity and efficient!'enhancement of the proposed push-pull structure

High Selectivity Coupled Line Impedance Transformer with Second Harmonic Suppression

  • Kim, Phirun;Park, Junsik;Jeong, Junhyung;Jeong, Seungho;Chaudhary, Girdhari;Jeong, Yongchae
    • Journal of electromagnetic engineering and science
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    • v.16 no.1
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    • pp.13-18
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    • 2016
  • This paper presents a design of an impedance transformer (IT) with high frequency selectivity characteristics. The frequency selectivity can be controlled by even- and odd-mode impedance of a shunt coupled transmission line (TL). For experimental validation, a 50- to $20-{\Omega}$ IT was implemented at a center frequency ($f_0$) of 2.6 GHz for the long-term evolution signal. The measured results were in good agreement with the simulations, showing a return loss higher than 19 dB over a passband bandwidth of 0.63 GHz (2.28-2.91 GHz) and good sharp frequency selectivity characteristic near to the passband. The series coupled TL provides a transmission zero at 5.75 GHz, whereas the shunt coupled TL provides three transmission zeros located at 2 GHz, 3.1 GHz, and 7.14 GHz.

An Indirect Method to Monitor Plasma Status in a Transformer Coupled Plasma

  • Yu, Dae-Ho;An, Seung-Gyu;Kim, Ji-Hun;Jang, Hong-Yeong
    • Proceedings of the Korean Vacuum Society Conference
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    • 2011.02a
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    • pp.216-216
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    • 2011
  • There have been various direct or indirect methods to measure the characteristics of plasma. Comparing to direct method like Langmuir probe method, indirect measurements which give information as some external parameters like current, voltage, or phase are easier to obtain. In this research, an indirect method to measure averaged plasma density in a transformer coupled plasma(TCP) has been proposed and evaluated. With a simple analytic model connecting electrical characteristics to plasma impedance, direct measurement via double Langmuir probe has been performed. This result may play a meaningful role to diagnose TCP or similar plasma sources

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Test and Analysis of 3-D of Leakage Impedances in a Single-Phase 1MVA HTS Transformer (단상 1MVA 고온초전도 변압기의 누설임피던스 3차원 해석 및 시험)

  • Kim, Sung-Hoon;Kim, Woo-Seok;Lee, Sang-Jin;Choi, Kyeong-Dal;Joo, Hyeong-Gil;Hong, Gye-Won;Han, Jin-Ho;Hahn, Song-Yop;Song, Hee-Suck;Park, Jung-Ho
    • Proceedings of the KIEE Conference
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    • 2003.07b
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    • pp.1003-1005
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    • 2003
  • In this paper, 3-D nonlinear electromagnetic analysis of a single phase 1MVA 22.9 kV/6.6 kV high temperature superconducting(HTS) transformer with double pancake windings was accomplished. The characteristics of 1MVA HTS transformer such as The efficiency, voltage regulation and % impedance voltage drop were obtained by the 3-D non-linear electromagnetic analysis. And in order to verify the 3-D non-linear electromagnetic analysis of a single phase 1MVA HTS transformer, a 1MVA test transformer with windings made of copper tapes with the same size as BSCCO-2223 HTS tape was manufactured. The energy conservation method to perform the analysis of leakage impedances of both a 1MVA HTS transformer and test transformer was used. The characteristic analysis such as efficiency, voltage regulation and % impedance voltage drop of transformer was performed. And the obtained values of both 1MVA HTS transformer and test transformer were compared.

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The analysis of the operating characteristic for the wideband coaxial line impedance transformer (광대역 동축선로 임피던스 변환회로의 동작 특성 분석)

  • Park, Ung-hee
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.23 no.2
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    • pp.165-172
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    • 2019
  • Using two or more coaxial lines, if one port is connected in series and the other port is connected in parallel, it can be implemented the wideband transmission line transformer(TLT). Because the wideband TLT utilizes the outer conductor of the coaxial line, it is difficult to predict the characteristics. In this paper, based on the analysis for the transfer characteristic(S21) according to the loss of the each line in ${\lambda}/4$-microstrip line TLT, the operating characteristic of the fabricated wideband 4:1 TLT using two $25{\Omega}$-coaxial lines is investigated. The fabricated wideband TLT shows the notch characteristic in which the transfer signal sharply decreases at ${\lambda}/4$ frequency of the coaxial line and has a value within -0.2dB of the transfer characteristic(S21) in $0.06{\sim}0.2{\lambda}$ frequency range of the coaxial line. This transfer characteristics(S21) can change the operating frequency range slightly and set the optimum transfer characteristic(S21) at the desired frequency by changing the length of the microstrip line.

Impedance design of tap changing auto transformer based LVRT/HVRT test device (탭 변환 단권변압기 기반 LVRT/HVRT 시험장비의 임피던스 설계)

  • Baek, Seung-Hyuk;Kim, Dong-Uk;Yoon, Young-Doo;Kim, Sungmin
    • Journal of IKEEE
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    • v.24 no.1
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    • pp.216-224
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    • 2020
  • This paper proposes an impedance design method of the test device for evaluating Low Voltage Ride Through(LVRT) and High Voltage Ride Through(HVRT) functions. The LVRT/HVRT test device should have ability to generate the fault voltage specified in the grid code for a certain period and to limit the magnitude of the fault current with the design specification. In this paper, the impedance design method for auto transformer is proposed based on a equivalent model of a tap-change auto-transformer during LVRT/HVRT operation. In addition, to generate various fault voltages required the LVRT/HVRT test, tap impedance design in the auto transformer is considered. To verify the validity of the proposed design method, the design process of the 10MVA LVRT/HVRT test device was conducted and the design results was verified through simulation models.

V/UHF-Band Broadband 2-Way Power Divider (V/UHF-대역 광대역 2분기 전력 분배기)

  • Park, Yeo-Il;Ko, Jin-Hyun;Park, Young-Joo;Park, Dong-Chul
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.18 no.4 s.119
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    • pp.416-422
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    • 2007
  • In this paper, a broadband 2-way power divider which can be used from 20 MHz to 500 MHz in the V/UHF band is designed using transmission-line transformer and ferrite toroid. A 2:1 impedance transformer instead of the conventional 4:1 impedance transformer is realized and this 2:1 transformer is connected with the conventional bridge-type 2-way divider to form a 2-way power divider. Insertion loss of about 3.5 dB, isolation of less than -10 dB, and return loss of less than -10 dB in most band of interest are measured.

Design Analysis of Step-down Multilayer Piezoelectric Transformer

  • Hoonbum Shin;Hyungkeun Ahn;Han, Deuk-Young
    • Journal of Power Electronics
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    • v.3 no.2
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    • pp.139-144
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    • 2003
  • In this paper, 11 and 13 layered step-down piezoelectric transformers were fabricated and their electrical characteristics have been analyzed for AC-adapter. When the voltage is applied to the driving piezoelectric vibrator polarized in the longitudinal direction, the output voltage is generated at the generating piezoelectric vibrator polarized in the thickness direction due to the piezoelectric effects. From the piezoelectric direct and converse effects, symbolic expressions between the electric inputs and outputs of the step-down piezoelectric transformer are derived with an equivalent circuit model. With those expressions, load and frequency characteristics are discussed through the simulations. Output voltage and current from a 11-layered and a 13-layered piezoelectric transformers were measured under the different load and frequency conditions. First we measured resonant frequency from impedance curve and got equivalent impedance value of the piezoelectric transformer from admittance plot. It was shown from experiments that output voltage increase s and resonant frequency changes according to the various resistor loads. Output current decreases inversely proportional to the change of loads. Moreover, the measured output voltage and current are well matched with the simulated results obtained from the proposed equivalent circuit model. Furthermore, a new step-down piezoelectric transformer has been suggested to Increase the output power based on a simulation result having a driving piezoelectric vibrator polarized thickness direction.

Conceptual Design of a Single Phase 33 MVA HTS Transformer with a Tertiary Winding (3차 권선을 고려한 단상 33MVA 고온초전도 변압기의 개념설계)

  • Lee, S.W.;Kim, W.S.;Hahn, S.Y.;Hwang, Y.I.;Choi, K.D.
    • Progress in Superconductivity
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    • v.7 no.2
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    • pp.162-166
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    • 2006
  • We have proposed a 3 phase, 100 MVA, 154 kV class HTS transformer substituting for a 60 MVA conventional transformer. The power transformer of 154 kV class has a tertiary winding besides primary and secondary windings. So the HTS transformer should have the 3rd superconducting winding. In this paper, we designed conceptually the structure of the superconducting windings of a single phase 33 MVA transformer. The electrical characteristics of the HTS transformer such as % impedance and AC loss vary with the arrangement of the windings and gaps between windings. We analyzed the effects of the winding parameters, evaluated the cost of each design, and proposed a suitable HTS transformer model for future power distribution system.

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Application of Expanding-cell FDTD Method to Microstrip-to-Waveguide Transition (Expanding-cell 유한차분법의 마이크로스트립-도파관 변환기에의 적용)

  • 강희진;최재훈
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.11 no.3
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    • pp.345-351
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    • 2000
  • In this paper, we design and analyze a Ka-band microstrip line to rectangular waveguide transition using the expanding-cell FDTD method. The transition under investigation consists of a ridged waveguide, microstrip line, and $\lambda$/4 Chebyshev impedance transformer. To improve the accuracyand efficiency, the expanding-cell FDTD method is applied to analyze the characteristics of a ridged waveguide impedance transformer. To verify the accuracy of the expanding-cell FDTD method, S parameters of the analyzed transition are compared with those of experimental data. The efficiency of the present approach is verified by comparing the computational time for expanding-cell and that for fine cell. The relation between the number of step and operation bandwidth is analyzed by comparing the characteristics of four and three step Chebyshev waveguide impedance transformer.

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