• Title, Summary, Keyword: frequency conversion

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Super-High Speed Photo detection through Frequency Conversion for Microwave on Optical Network

  • Choi, Young-Kyu;Shin, Sang-Yeol
    • Journal of information and communication convergence engineering
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    • v.6 no.4
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    • pp.439-443
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    • 2008
  • It is shown that even if the modulating frequency of the light is too high for direct detection the signal can be extracted by frequency conversion at the same time as the detection by means of the nonlinearity of the APD. When this frequency conversion detection is applied to an optical receiver, the detection bandwidth can be increased while the configuration of the optical detection circuit and the signal processing in the subsequent stages are simplified. A fundamental analysis is carried out with an APD which is confirmed experimentally.

Utility AC Frequency to High Frequency ACPower Conversion Circuit with Soft Switching PWM Strategy

  • Sugimura Hisayuki;Ahmed Nabil A.;Ahmed Tarek;Lee Hyun-Woo;Nakaoka Mutsuo
    • KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
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    • v.5B no.2
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    • pp.181-188
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    • 2005
  • In this paper, a DC smoothing filterless soft switching pulse modulated high frequency AC power conversion circuit connected to utility. frequency AC power source is proposed for consumer induction heating hot water producer, steamer and super heated steamer. The operating principle of DC link filterless utility frequency AC-high frequency AC (HF AC) power conversion circuit defined as high frequency cycloinverter is described, which can operate under a principle of ZVS/AVT and power regulation based on alternate asymmetrical PWM in synchronization with the utility frequency single phase AC positive or negative half wave voltage. The dual mode modulation control scheme based on high frequency PWM and commercial frequency AC voltage PDM for the proposed high frequency cycloinverter are discussed to enlarge its soft switching commutation operating range for wide HF AC power regulation. This high frequency cycloinverter is developed for high frequency IH Dual Packs Heater (DPH) type boiler used in consumer and industrial fluid pipeline systems. Based on the experiment and simulation results, this high frequency cycloinverter is proved to be suitable for the consumer use IH-DPH boiler and hot water producers. The cycloinverter power regulation and power conversion efficiency characteristics are evaluated and discussed.

Bilingual Voice Conversion Using Frequency Warping on Formant Space (포만트 공간에서의 주파수 변환을 이용한 이중 언어 음성 변환 연구)

  • Chae, Yi-Geun;Yun, Young-Sun;Jung, Jin Man;Eun, Seongbae
    • Phonetics and Speech Sciences
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    • v.6 no.4
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    • pp.133-139
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    • 2014
  • This paper describes several approaches to transform a speaker's individuality to another's individuality using frequency warping between bilingual formant frequencies on different language environments. The proposed methods are simple and intuitive voice conversion algorithms that do not use training data between different languages. The approaches find the warping function from source speaker's frequency to target speaker's frequency on formant space. The formant space comprises four representative monophthongs for each language. The warping functions can be represented by piecewise linear equations, inverse matrix. The used features are pure frequency components including magnitudes, phases, and line spectral frequencies (LSF). The experiments show that the LSF-based voice conversion methods give better performance than other methods.

Numerical Study on Frequency Up-conversion in USPR using MATLAB

  • Roh, Young-Su
    • Journal of Electrical Engineering and Technology
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    • v.5 no.3
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    • pp.497-502
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    • 2010
  • In this paper, the O-mode ultrashort-pulse reflectometry (USPR) millimeter-wave signals that propagate into the plasma and cover a frequency bandwidth of 33-158 GHz are examined numerically using MATLAB. Two important processes are involved in the computation: the propagation of the USPR impulse signal through a waveguide and the frequency up-conversion using millimeter-wave mixers. These mixers are limited to intermediate frequency signals that are less than 500 mV; thus, it is necessary to disperse the impulse signal into a chirped waveform using the waveguide. The stationary phase method is utilized to derive a closed-form formula for a chirped waveform under the assumption that the USPR impulse is Gaussian. In the process of frequency up-conversion, the chirped waveform is mixed with the mixer LO signal, and the lower frequency components of the RF signal are removed using high pass filters.

A Novel Power Frequency Changer Based on Utility AC Connected Half-Bridge One Stage High Frequency AC Conversion Principle

  • Saha Bishwajit;Koh Kang-Hoon;Kwon Soon-Kurl;Lee Hyun-Woo;Nakaoka Mutsuo
    • Proceedings of the KIPE Conference
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    • pp.203-205
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    • 2006
  • This paper presents a novel soft-switching PWM utility frequency AC to high frequency AC power conversion circuit incorporating boost-half-bridge inverter topology, which is more suitable and acceptable for cost effective consumer induction heating applications. The operating principle and the operation modes are presented using the switching mode and the operating voltage and current waveforms. The performances of this high-frequency inverter using the latest IGBTs are illustrated, which includes high frequency power regulation and actual efficiency characteristics based on zero voltage soft switching (ZVS) operation ranges and the power dissipation as compared with those of the previously developed high-frequency inverter. In addition, a dual mode control scheme of this high frequency inverter based on asymmetrical pulse width modulation (PWM) and pulse density modulation (PDM) control scheme is discussed in this paper in order to extend the soft switching operation ranges and to improve the power conversion efficiency at the low power settings. The power converter practical effectiveness is substantially proved based on experimental results from practical design example.

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A New Compact Double Conversion Gate Mixer using a Half-LO Frequency

  • Lee, Jae-Ryong;Yun, Sang-Won
    • Journal of electromagnetic engineering and science
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    • v.2 no.1
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    • pp.56-58
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    • 2002
  • In this paper, the double conversion gate mixer using a half-LO frequency is described at 25 GHz band. The proposed mixer uses two HEMTs excited by a single LO signal of half-LO frequency in order to generate the second IF signal. That is, the LO signal having the half-LO frequency is only fed into the gate of the first HEMT mixer as a normal gate mixer. The LO signal through the first mixer is find into the second mixer The proposed miler requires not only half of the normal LO frequency, but also lower LO power than the conventional subharmonically pumped milers. Over the bandwidth of 500 MHz at 24.5 GHz, the conversion gain is 2.5 dB, the noise figure is 9 dB, and the isolation between RF and LO port is 32 dB when the LO poller is 0 dBm at 12.65 GHz.

Design and Implementation of an Analog Predistorter for M/W Repeaters (M/W 중계기용 아날로그 Predistorter의 설계 및 구현)

  • Kang, Sang-Gee;Ryu, Joon-Gyu;Chang, Dae-Ig
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.12 no.1
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    • pp.33-38
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    • 2008
  • The probability of an oscillation occurrence in M/W frequency conversion repeaters is low on account of the different operating frequency of the input and output signals. The probability of interference caused by the M/W frequency conversion repeaters to other systems is also low because the systems are used in the line-of-sight. Therefore M/W frequency conversion repeaters are generally used for retransmitting the signal received from base station to the islands. This paper describes the design and implementation of analog predistorter for M/W frequency conversion repeaters in mobile communications. The M/W repeaters convert IF frequency of 1010+/-10MHz to RF frequency of 11GHz. A predistorter can be designed for the M/W repeater operating in either IF or M/W frequency. In this paper IF predistorter operated in 1010MHz is designed and implemented because a M/W predistorter operated in 11GHz is difficult to implement. The IF predistorter can linearize RF modules in the repeater followed by IF stages. The performance test results show that the implemented analog predistorter improves ACPR of 10dB at the output power of 25dBm with the signal frequency of 10.805GHz.

Design of Double-Conversion Down Mixer Using Single Half-LO Frequency at 2.3 GHz (2.3 GHz 대역에서 단일 Half-LO 주파수를 이용한 Double-Conversion Down Mixer 설계)

  • Kim Min-Seok;Moon Ju-Young;Yun Sang-Won
    • The Journal of Korean Institute of Electromagnetic Engineering and Science
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    • v.17 no.8
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    • pp.719-724
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    • 2006
  • In this paper, we designed the double conversion down mixer by using Half-LO frequency in 2.3 GHz band. The IF frequency is obtained by supplying two LO frequencies to HEMT in both gate type and resistive type. The proposed mixer uses Half-LO frequency the same way as conventional sub-harmonic mixers. However the proposed one uses fundamental component of Half-LO frequency in first stage instead of using second harmonic components of Half-LO frequency, and the IF frequency is obtained by resistive type mixer in second stage, thereby the proposed mixer can improve linearity in comparison with conventional active mixer. We can verify that the proposed mixer has an conversion loss of 5dBm and IIP3 of 16.25dBm by using 10 dBm Power.

VARIABLE SPEED CONSTANT FREQUENCY POWER CONVERSION WITH A SWITCHED RELUCTANCE MACHINE

  • Rim, Geun-Hie;Krishnan, R.
    • Proceedings of the KIEE Conference
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    • pp.1030-1034
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    • 1993
  • A converter topology which is capable of four-quadrant(motoring and generation) operation is proposed for the variable speed constant frequency(hereafter referred as VSCF) power conversion scheme. The new converter topology for the VSCF power conversion scheme is made of two functional stages. One is converting stage which consists of six switches and six diodes and it interfaces a three-phase 60Hz at supply and a single-phase variable-frequency ac source. The other is the commutating stage though which each phase-winding is energized.

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Rectifier Design Using Distributed Greinacher Voltage Multiplier for High Frequency Wireless Power Transmission

  • Park, Joonwoo;Kim, Youngsub;Yoon, Young Joong;So, Joonho;Shin, Jinwoo
    • Journal of electromagnetic engineering and science
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    • v.14 no.1
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    • pp.25-30
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    • 2014
  • This paper discusses the design of a high frequency Greinacher voltage multiplier as rectifier; it has a greater conversion efficiency and higher output direct current (DC) voltage at high power compared to a simple halfwave rectifier. Multiple diodes in the Greinacher voltage multiplier with distributed circuits consume excited power to the rectifier equally, thereby increasing the overall power capacity of the rectifier system. The proposed rectifiers are a Greinacher voltage doubler and a Greinacher voltage quadrupler, which consist of only diodes and distributed circuits for high frequency applications. For each rectifier, the RF-to-DC conversion efficiency and output DC voltage for each input power and load resistance are analyzed for the maximum conversion efficiency. The input power with maximum conversion efficiency of the designed Greinacher voltage doubler and quadrupler is 3 and 7 dB higher, respectively;than that of the halfwave rectifier.