• Title/Summary/Keyword: bias modulator

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Transient Chirp Analysis of Ml-DFB Laser Module (Transient chirp 측정을 이용한 Modulator 집적 DFB 레이저 모듈의 특성해석)

  • 오윤경;곽계달
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.35D no.9
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    • pp.35-41
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    • 1998
  • A transient chirp measurement was used to analyze the chirping characteristics of modulator integrated DFB (MI-DFB) laser module. This method measures the wavelength change due to a small variation in modulation with bias. The measurement system includes a monochrometer and digitizing oscilloscope. The chirping characteristics due to packaging influences can also be accounted for. The chirp parameter calculated using this method was compared with the peak-to peak chirp. They showed the same tendency with modulator bias voltage. These results can be used as a reference when optimizing system parameters.

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A CMOS Envelope Tracking Power Amplifier for LTE Mobile Applications

  • Ham, Junghyun;Jung, Haeryun;Kim, Hyungchul;Lim, Wonseob;Heo, Deukhyoun;Yang, Youngoo
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.14 no.2
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    • pp.235-245
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    • 2014
  • This paper presents an envelope tracking power amplifier using a standard CMOS process for the 3GPP long-term evolution transmitters. An efficiency of the CMOS power amplifier for the modulated signals can be improved using a highly efficient and wideband CMOS bias modulator. The CMOS PA is based on a two-stage differential common-source structure for high gain and large voltage swing. The bias modulator is based on a hybrid buck converter which consists of a linear stage and a switching stage. The dynamic load condition according to the envelope signal level is taken into account for the bias modulator design. By applying the bias modulator to the power amplifier, an overall efficiency of 41.7 % was achieved at an output power of 24 dBm using the 16-QAM uplink LTE signal. It is 5.3 % points higher than that of the power amplifier alone at the same output power and linearity.

Off-level Sampling Method for Bias Stabilization of an Electro-Optic Mach-Zehnder Modulator (전기 광학 광변조기의 바이어스 안정화를 위한 오프 레벨 샘플링 방법)

  • 양충열;홍현하;김해근
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.25 no.1B
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    • pp.42-47
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    • 2000
  • A new method for stabilizing the bias of an Electro-Optic mach-Zehnder modulator has been developed to maximize the switching extinction ratio in burst mode packet traffic. By sampling and minimizing the off-level output power of the modulator, a high extinction optical gate switch in obtain regardless of the variation of the packet traffic density.

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Jitter Reduction by Modulator-Bias Control in Analog Fiber-Optic Links Employing a Mach-Zehnder Modulator Followed by an Erbium-Doped Fiber Amplifier (마하-젠더 광 변조기와 EDFA로 구성된 아날로그 광통신 링크에서 변조기 바이어스 조정을 이용한 랜덤 지터의 감소)

  • Lee, Min-Young;Yoon, Young-Min;Shin, Jong-Dug
    • Journal of IKEEE
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    • v.13 no.4
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    • pp.103-109
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    • 2009
  • We report an efficient jitter reduction technique in an analog fier-optic link employing a Mach-Zehnder modulator followed by an erbium-doped fiber amplifier. By adjusting the modulator-bias to $0.089V_{\pi}$, we could increase the RF gain up to 10.65 dB for 10 GHz RF signal and reduce the random jitter by 46.5%, max, at an input optical power of -0.11 dBm to the EDFA.

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Linearity of All Optical Dual EA Modulator for Narrow-band Microwave Optical Transmissions (협대역 마이크로파 광전송을 위한 전광 이중 전계흡수 광변조기의 선형특성)

  • Lee, Gyu-Woong;Han, Sang-Kook
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.36D no.6
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    • pp.87-96
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    • 1999
  • For analog optical transmission of narrow-band microwave signal, a novel all-optical linearization technique of electro-absorption (EA) optical modulator by using dual modulation scheme is proposed and theoretically investigated. By using the dual modulation scheme where the sub-modulator has a different length, DC bias and band-gap wavelength, the DC bias operation point where the third-order intermodulation products of ~30dB and the following increase of spurious free dynamic range (SFDR) of ~20dB wave achieved in sub-octave narrow band operation.

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Optic Link Performances on EOM′s Biasing in Fiber-radio System (주파수 천이를 이용한 광무선 시스템에서 EOM의 바이어스 방식에 따른 광링크 성능 분석)

  • O, Se-Hyeok;Yang, Hun-Gi;Choe, Yeong-Wan
    • Journal of the Institute of Electronics Engineers of Korea SD
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    • v.38 no.2
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    • pp.128-136
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    • 2001
  • This paper evaluates the performance of an optic link in a frequency conversion based fiber-radio system. The proposed link structure simplifies a BS(base station) via making the MMW(millimeter wave) optical pilot tone generated in the CS(control station) be used in the uplink as well as in the downlink. To acquire the optical pilot tone, an EOM(electro-optic modulator) in the CS is biased in three different ways, i.e., MAB(maximum bias), MIB(minimum bias), QB(quadrature bias). We, depending on the biasing of the EOM, evaluate the link performances in two cases; one is for constant laser source power and the other for constant received DC optical power at a PD(photo detector). Based on the simulation results on the downlink CNR and the uplink SFDR(spurious free dynamic range), we finally deduce the effective EOM biasing for each case.

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Dual Bias Modulator for Envelope Tracking and Average Power Tracking Modes for CMOS Power Amplifier

  • Ham, Junghyun;Jung, Haeryun;Bae, Jongsuk;Lim, Wonseob;Hwang, Keum Cheol;Lee, Kang-Yoon;Park, Cheon-Seok;Yang, Youngoo
    • JSTS:Journal of Semiconductor Technology and Science
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    • v.14 no.6
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    • pp.802-809
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    • 2014
  • This paper presents a dual-mode bias modulator (BM) for complementary metal oxide semiconductor (CMOS) power amplifiers (PAs). The BM includes a hybrid buck converter and a normal buck converter for an envelope tracking (ET) mode for high output power and for an average power tracking (APT) mode for low output power, respectively. The dual-mode BM and CMOS PA are designed using a $0.18-{\mu}m$ CMOS process for the 1.75 GHz band. For the 16-QAM LTE signal with a peak-to-average power ratio of 7.3 dB and a bandwidth of 5 MHz, the PA with the ET mode exhibited a poweradded efficiency (PAE) of 39.2%, an EVM of 4.8%, a gain of 19.0 dB, and an adjacent channel leakage power ratio of -30 dBc at an average output power of 22 dBm, while the stand-alone PA has a PAE of 8% lower at the same condition. The PA with APT mode has a PAE of 21.3%, which is an improvement of 13.4% from that of the stand-alone PA at an output power of 13 dBm.

Design and Fabrication of 5.5GHZ SSB optical modulator with polarization reversed structure (LiINbO3 기판의 분극반전을 이용한 5.5 GHz 대역 SSB 광변조기의 설계 및 제작)

  • Jeong, W.J.;Kim, W.K.;Yang, W.S.;Lee, H.M.;Lee, H.Y.;Kwon, S.W.
    • Korean Journal of Optics and Photonics
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    • v.17 no.2
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    • pp.175-180
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    • 2006
  • A single sideband(SSB) modulator operating at 5.5 GHz was fabricated by polarization inversion techniques. The dimension of domain inversion in a $LiINbO_3$ Mach-Zehnder structure was precisely controlled so that the RF signal applied on two Mach-Zehnder arms gives rise to $90^{\circ}$ effective phase difference. The single sideband suppression was maximized by optimization of the polarization status of the optical input and by the DC bias value. The fabricated device showed the center frequency of 5.8 GHz and the maximum sideband suppression of 33dB, where the bandwidth of 15 dB sideband suppression ranged over a 2.5 GHz span. The optical phase delay could be regulated by the DC bias voltage, fur example, the enhanced optical modulation sideband was distinctively switched from the upper sideband to the lower sideband by changing the DC bias voltage from 1.9 V to -10.6 V.

Chirping Characteristics Analysis of Electroabsorption Modulators by Riber Transmission Simulations (전송 모의실험을 통한 전계흡수 광변조기의 파장왜곡 특성해석)

  • Han, Sub;Kim, Kyung-Hyun;Han, Sang-Kook
    • Journal of the Korean Institute of Telematics and Electronics D
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    • v.35D no.5
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    • pp.93-99
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    • 1998
  • The chirping characteristics of InGaAsP electroabsorption modulatiors have been analyzed. The effective .alpha. parameters for large signal modulation were estimated by comparing the pulse shape after fiber transmission with constant chirping assumption.We investigated the structure and the operating condition of the modulator to improve the chirping characteristics. The .alpha. parameters were calculated as the function of wavelength detuning and the bias voltage. To minimize the chirping performance, high bias voltage and a small wavelength detuning and the bias voltage. To minimize the chirping performance, high bias voltage and a small wavelength detuning were preferred. An negative .alpha. value is achieved at the wavelength detuning below 30meV with a proper bias voltage so that pulse compression effect was expected.

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Automatic Off Level Biasing for Electro Optic Mach-Zehnder Modulator (전기적 외부 광변조기의 자동 오프레벨 바이어싱)

  • Yang, Choong-Reol;Ko, Je-Soo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.32 no.7A
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    • pp.672-677
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    • 2007
  • A novel method for stabilizing the bias of an Electro-Optic Mach-Zehnder modulator has been proposed and demonstrated to maximize the switching extinction ratio in burst mode packet traffic. By sampling and minimizing the off-level output power of the modulator, a high extinction optical gate switch in obtain regardless of the variation of the packet traffic density.