The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform
Bumman Kim - One of the best experts on this subject based on the ideXlab platform.
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linear doherty Power amplifier with an enhanced back off efficiency Mode for handset applications
IEEE Transactions on Microwave Theory and Techniques, 2014Co-Authors: Yunsung Cho, Jooseung Kim, Byungjoon Park, Daehyun Kang, Kyunghoon Moon, Bumman KimAbstract:This paper presents a linear Doherty Power amplifier (PA) with enhanced back-off efficiency Mode for handset applications. For linear Doherty operation, we analyze the gain modulation as well as the cancellation of the third-order intermodulation distortion in order to improve the linearity. A compact design method is also discussed to implement on a single chip for a handset. The proposed Doherty PA delivers good performance with regard to the third-generation (3G)/fourth-generation (4G) modulation signals. A switched-load Power-Mode PA is adopted in the proposed Doherty PA to enhance the efficiency in the low-Power region with over 10-dB back-off. For demonstration purposes, the PA is implemented using an InGaP/GaAs heterojunction bipolar transistor and AlGaAs/InGaAs pseudomorphic high electron-mobility transistor process. The PA is tested at 1.85 GHz using both a long-term evolution signal with 16-quadrature amplitude modulation, 7.5-dB peak-to-average Power ratio, and 10-MHz bandwidth (BW) and a wideband code division multiple access signal with 3.3-dB PAPR and 3.84-MHz BW. The proposed linear Doherty PA with an enhanced back-off efficiency Mode delivers good performance in both the high- and low-Power Modes, implying that the dual-Power-Mode Doherty PA configuration can be a promising candidate for extending the battery life of handheld devices in 3G and 4G wireless communication systems.
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A dual Power-Mode multi-band Power amplifier with envelope tracking for handset applications
IEEE Transactions on Microwave Theory and Techniques, 2013Co-Authors: Yunsung Cho, Jooseung Kim, Dongsu Kim, Byungjoon Park, Daehyun Kang, Bumman KimAbstract:This paper presents a dual Power-Mode and multi-band Power amplifier (PA) for handset applications that improves the efficiency in low-Power regions. This PA operates in two Modes through path control by a shunt switched capacitor. The proposed control method provides efficient Mode control without any efficiency degrading and bandwidth (BW) limiting. The proposed PA, in conjunction with a boosted supply modulator for envelope tracking (ET) operation not only in the high-Power Mode, but also in the low-Power Mode, delivers good performance at all average output Power levels. The linearity is improved by ET through a proper envelope-shaping method. For demonstrative purposes, the PA and supply modulator are implemented using an InGaP/GaAs heterojunction bipolar transistor and AIGaAs/InGaAs enhancement/depletion-Mode pseudomorphic high electron-mobility transistor process and a 0.18-μ m CMOS process, respectively. The ET PA is tested across the range of 1.7-2.0 GHz using a long-term evolution signal with 16 quadrature amplitude modulation, a 7.5-dB peak-to-average Power ratio, and 10-MHz BW. The proposed dual Power-Mode multi-band ET PA delivers good performance for high- and low-Power Modes, indicating that the architecture is promising for handset PA applications.
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a handset Power amplifier with high efficiency at a low level using load modulation technique
IEEE Transactions on Microwave Theory and Techniques, 2005Co-Authors: Joongjin Nam, Jinho Shin, Bumman KimAbstract:A new monolithic-microwave integrated-circuit Power amplifier for cellular handsets has been implemented using the load-modulation concept of the Doherty amplifier, which has a high efficiency at a low Power level. In order to get a compact module, the /spl lambda//4 transmission line for the load modulation is replaced by a passive high-pass /spl pi/-network, and the load-modulation circuit is also modified to function as a Power-matching circuit of the main amplifier. The amplifier has two Modes of operation, low- and high-Power Modes, controlled by a control voltage. At the high Power Mode, both the main and auxiliary amplifiers are operational and, at the low Power Mode, only the main amplifier generates output Power enhancing the efficiency. For the code-division multiple-access environment, the amplifier at the low-Power Mode provides Power-added efficiency (PAE) of 39.8% and an adjacent channel Power ratio (ACPR) less than 49.8 dBc at 23.1 dBm, and the high-Power Mode PAE of 37.9% and ACPR of 46.4 dBc at 28 dBm. The efficiency is improved by approximately 18.8% at P/sub out/=23 dBm by the load-modulation technique. For the advanced mobile phone system-Mode operation, the amplifier delivers 26.1 dBm with PAE of 53% and 30.8 dBm with 48.7% at the low and high Modes, respectively.
Byungjoon Park - One of the best experts on this subject based on the ideXlab platform.
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linear doherty Power amplifier with an enhanced back off efficiency Mode for handset applications
IEEE Transactions on Microwave Theory and Techniques, 2014Co-Authors: Yunsung Cho, Jooseung Kim, Byungjoon Park, Daehyun Kang, Kyunghoon Moon, Bumman KimAbstract:This paper presents a linear Doherty Power amplifier (PA) with enhanced back-off efficiency Mode for handset applications. For linear Doherty operation, we analyze the gain modulation as well as the cancellation of the third-order intermodulation distortion in order to improve the linearity. A compact design method is also discussed to implement on a single chip for a handset. The proposed Doherty PA delivers good performance with regard to the third-generation (3G)/fourth-generation (4G) modulation signals. A switched-load Power-Mode PA is adopted in the proposed Doherty PA to enhance the efficiency in the low-Power region with over 10-dB back-off. For demonstration purposes, the PA is implemented using an InGaP/GaAs heterojunction bipolar transistor and AlGaAs/InGaAs pseudomorphic high electron-mobility transistor process. The PA is tested at 1.85 GHz using both a long-term evolution signal with 16-quadrature amplitude modulation, 7.5-dB peak-to-average Power ratio, and 10-MHz bandwidth (BW) and a wideband code division multiple access signal with 3.3-dB PAPR and 3.84-MHz BW. The proposed linear Doherty PA with an enhanced back-off efficiency Mode delivers good performance in both the high- and low-Power Modes, implying that the dual-Power-Mode Doherty PA configuration can be a promising candidate for extending the battery life of handheld devices in 3G and 4G wireless communication systems.
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A dual Power-Mode multi-band Power amplifier with envelope tracking for handset applications
IEEE Transactions on Microwave Theory and Techniques, 2013Co-Authors: Yunsung Cho, Jooseung Kim, Dongsu Kim, Byungjoon Park, Daehyun Kang, Bumman KimAbstract:This paper presents a dual Power-Mode and multi-band Power amplifier (PA) for handset applications that improves the efficiency in low-Power regions. This PA operates in two Modes through path control by a shunt switched capacitor. The proposed control method provides efficient Mode control without any efficiency degrading and bandwidth (BW) limiting. The proposed PA, in conjunction with a boosted supply modulator for envelope tracking (ET) operation not only in the high-Power Mode, but also in the low-Power Mode, delivers good performance at all average output Power levels. The linearity is improved by ET through a proper envelope-shaping method. For demonstrative purposes, the PA and supply modulator are implemented using an InGaP/GaAs heterojunction bipolar transistor and AIGaAs/InGaAs enhancement/depletion-Mode pseudomorphic high electron-mobility transistor process and a 0.18-μ m CMOS process, respectively. The ET PA is tested across the range of 1.7-2.0 GHz using a long-term evolution signal with 16 quadrature amplitude modulation, a 7.5-dB peak-to-average Power ratio, and 10-MHz BW. The proposed dual Power-Mode multi-band ET PA delivers good performance for high- and low-Power Modes, indicating that the architecture is promising for handset PA applications.
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envelope tracking two stage Power amplifier with dual Mode supply modulator for lte applications
IEEE Transactions on Microwave Theory and Techniques, 2013Co-Authors: Daehyun Kang, Byungjoon ParkAbstract:This paper presents an envelope tracking Power amplifier (ET PA) using a dual-Mode supply modulator for handset application. The supply modulator has a combined structure with a linear amplifier and a switching amplifier. The dual-Mode supply modulator operates in high-Power Mode and low-Power Mode by providing the supply voltage of the linear amplifier of 5 and 2.5 V, respectively. For 1.74-GHz long-term evolution signal with 10-MHz bandwidth, 6.44-dB peak-to-average Power ratio, and 16-quadrature amplitude modulation, the ET PA delivers a Power-added efficiency (PAE) of 39.8%, an evolved universal terrestrial radio access adjacent channel leakage ratio (E-UTRAACLR) of - 35.7 dBc, and an error vector magnitude (EVM) of 3.81% at an average output Power of 27 dBm. The ET PA also delivers a PAE of 22.6% at an average output Power of 18 dBm, which is 6.6% higher than that of the conventional ET PA and 13.1% higher than that of the standalone PA. The supply modulator is connected to a drive stage and a Power stage of the PA simultaneously for further enhanced efficiency at a Power back-off region. The dual-Mode two-stage ET PA delivers a PAE of 38.1%, an E-UTRAACLR of - 32.9 dBc, and an EVM of 4.74% at an average output Power of 27 dBm. The dual-Mode two-stage ET PA also delivers a PAE of 26.3% at an average output Power of 18 dBm, which is 7.8% higher than that of the conventional two-stage ET PA and 16.7% higher than that of the standalone PA.
Nobuhiko Sarukura - One of the best experts on this subject based on the ideXlab platform.
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high repetition rate high average Power Mode locked ti sapphire laser with an intracavity continuous wave amplification scheme
Applied Physics Letters, 1999Co-Authors: S Izumida, Hideyuki Ohtake, Nobuhiko SarukuraAbstract:We have demonstrated a high-average-Power, Mode-locked Ti:sapphire laser with an intracavity continuous-wave amplification scheme. The laser generated 150 fs pulses with 3.4 W average Power at a repetition rate of 79 MHz. This simple amplification scheme can be applied for the Power scaling of other lasers.
Daehyun Kang - One of the best experts on this subject based on the ideXlab platform.
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linear doherty Power amplifier with an enhanced back off efficiency Mode for handset applications
IEEE Transactions on Microwave Theory and Techniques, 2014Co-Authors: Yunsung Cho, Jooseung Kim, Byungjoon Park, Daehyun Kang, Kyunghoon Moon, Bumman KimAbstract:This paper presents a linear Doherty Power amplifier (PA) with enhanced back-off efficiency Mode for handset applications. For linear Doherty operation, we analyze the gain modulation as well as the cancellation of the third-order intermodulation distortion in order to improve the linearity. A compact design method is also discussed to implement on a single chip for a handset. The proposed Doherty PA delivers good performance with regard to the third-generation (3G)/fourth-generation (4G) modulation signals. A switched-load Power-Mode PA is adopted in the proposed Doherty PA to enhance the efficiency in the low-Power region with over 10-dB back-off. For demonstration purposes, the PA is implemented using an InGaP/GaAs heterojunction bipolar transistor and AlGaAs/InGaAs pseudomorphic high electron-mobility transistor process. The PA is tested at 1.85 GHz using both a long-term evolution signal with 16-quadrature amplitude modulation, 7.5-dB peak-to-average Power ratio, and 10-MHz bandwidth (BW) and a wideband code division multiple access signal with 3.3-dB PAPR and 3.84-MHz BW. The proposed linear Doherty PA with an enhanced back-off efficiency Mode delivers good performance in both the high- and low-Power Modes, implying that the dual-Power-Mode Doherty PA configuration can be a promising candidate for extending the battery life of handheld devices in 3G and 4G wireless communication systems.
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A dual Power-Mode multi-band Power amplifier with envelope tracking for handset applications
IEEE Transactions on Microwave Theory and Techniques, 2013Co-Authors: Yunsung Cho, Jooseung Kim, Dongsu Kim, Byungjoon Park, Daehyun Kang, Bumman KimAbstract:This paper presents a dual Power-Mode and multi-band Power amplifier (PA) for handset applications that improves the efficiency in low-Power regions. This PA operates in two Modes through path control by a shunt switched capacitor. The proposed control method provides efficient Mode control without any efficiency degrading and bandwidth (BW) limiting. The proposed PA, in conjunction with a boosted supply modulator for envelope tracking (ET) operation not only in the high-Power Mode, but also in the low-Power Mode, delivers good performance at all average output Power levels. The linearity is improved by ET through a proper envelope-shaping method. For demonstrative purposes, the PA and supply modulator are implemented using an InGaP/GaAs heterojunction bipolar transistor and AIGaAs/InGaAs enhancement/depletion-Mode pseudomorphic high electron-mobility transistor process and a 0.18-μ m CMOS process, respectively. The ET PA is tested across the range of 1.7-2.0 GHz using a long-term evolution signal with 16 quadrature amplitude modulation, a 7.5-dB peak-to-average Power ratio, and 10-MHz BW. The proposed dual Power-Mode multi-band ET PA delivers good performance for high- and low-Power Modes, indicating that the architecture is promising for handset PA applications.
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envelope tracking two stage Power amplifier with dual Mode supply modulator for lte applications
IEEE Transactions on Microwave Theory and Techniques, 2013Co-Authors: Daehyun Kang, Byungjoon ParkAbstract:This paper presents an envelope tracking Power amplifier (ET PA) using a dual-Mode supply modulator for handset application. The supply modulator has a combined structure with a linear amplifier and a switching amplifier. The dual-Mode supply modulator operates in high-Power Mode and low-Power Mode by providing the supply voltage of the linear amplifier of 5 and 2.5 V, respectively. For 1.74-GHz long-term evolution signal with 10-MHz bandwidth, 6.44-dB peak-to-average Power ratio, and 16-quadrature amplitude modulation, the ET PA delivers a Power-added efficiency (PAE) of 39.8%, an evolved universal terrestrial radio access adjacent channel leakage ratio (E-UTRAACLR) of - 35.7 dBc, and an error vector magnitude (EVM) of 3.81% at an average output Power of 27 dBm. The ET PA also delivers a PAE of 22.6% at an average output Power of 18 dBm, which is 6.6% higher than that of the conventional ET PA and 13.1% higher than that of the standalone PA. The supply modulator is connected to a drive stage and a Power stage of the PA simultaneously for further enhanced efficiency at a Power back-off region. The dual-Mode two-stage ET PA delivers a PAE of 38.1%, an E-UTRAACLR of - 32.9 dBc, and an EVM of 4.74% at an average output Power of 27 dBm. The dual-Mode two-stage ET PA also delivers a PAE of 26.3% at an average output Power of 18 dBm, which is 7.8% higher than that of the conventional two-stage ET PA and 16.7% higher than that of the standalone PA.
Zeeshan Ahmed - One of the best experts on this subject based on the ideXlab platform.
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ultra sensitive chip based photonic temperature sensor using ring resonator structures
Optics Express, 2014Co-Authors: Mohammad Hafezi, Jingyun Fan, Jacob M Taylor, Gregory F Strouse, Zeeshan AhmedAbstract:Resistance thermometry provides a time-tested method for taking temperature measurements. However, fundamental limits to resistance-based approaches has produced considerable interest in developing photonic temperature sensors to leverage advances in frequency metrology and to achieve greater mechanical and environmental stability. Here we show that silicon-based optical ring resonator devices can resolve temperature differences of 1 mK using the traditional wavelength scanning methodology. An even lower noise floor of 80 μK for measuring temperature difference is achieved in the side-of-fringe, constant Power Mode measurement.
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ultra sensitive chip based photonic temperature sensor using ring resonator structures
arXiv: Optics, 2013Co-Authors: Mohammad Hafezi, Jingyun Fan, Jacob M Taylor, Gregory F Strouse, Zeeshan AhmedAbstract:Resistance thermometry provides a time-tested method for taking temperature measurements. However, fundamental limits to resistance-based approaches has produced considerable interest in developing photonic temperature sensors to leverage advances in frequency metrology and to achieve greater mechanical and environmental stability. Here we show that silicon-based optical ring resonator devices can resolve temperature differences of 1 mK using the traditional wavelength scanning methodology. An even lower noise floor of 80 microkelvin for measuring temperature difference is achieved in the side-of-fringe, constant Power Mode measurement.