Indium nitride thin films are grown on sapphire substrates by metal-organic chemical vapour deposition （MOCVD） By employing three-step layer buffers, the mirror-like layers on two-inch sapphire wafers have been obta...Indium nitride thin films are grown on sapphire substrates by metal-organic chemical vapour deposition （MOCVD） By employing three-step layer buffers, the mirror-like layers on two-inch sapphire wafers have been obtained. The structural, optical and electrical characteristics of InN are investigated by x-ray diffraction, scanning electron microscopy, atomic force microscopy, photoluminescence and infrared optical absorption. The photoluminescence and the absorption studies of the materials reveal a marked energy bandgap structure around 0.70eV at room temperature. The room-temperature Hall mobility and carrier concentration of the film are typically 939 cm^2 /Vs, and 3.9 × 1018cm^-3, respectively.展开更多
A C-band RF pulse compressor is in development at SINAP It comprises of two resonant cavities,two mode convertors and a 3 dB power divider.TE_(0.1.15)mode is selected for obtaining higher quality factor Q_0 of the RF ...A C-band RF pulse compressor is in development at SINAP It comprises of two resonant cavities,two mode convertors and a 3 dB power divider.TE_(0.1.15)mode is selected for obtaining higher quality factor Q_0 of the RF pulse compressor cavities,so that the power gain factor can be 3.2,which is supposed to multiply the RF power from 50 MW to 1 60 MW.In this paper,we report our work on C-band RF pulse compressor,namely the design simulation and cold test results.展开更多
A fully integrated dual-band RF receiver with a low-IF architecture is designed and implemented for GPS-L 1 and Compass-Bl in a 55-nm CMOS process. The receiver incorporates two independent IF channels with 2 or 4 MHz...A fully integrated dual-band RF receiver with a low-IF architecture is designed and implemented for GPS-L 1 and Compass-Bl in a 55-nm CMOS process. The receiver incorporates two independent IF channels with 2 or 4 MHz bandwidth to receive dual-band signals around 1.57 GHz respectively. By implementing a flexible frequency plan, the RF front-end and frequency synthesizer are shared for the dual-band operation to save power consumption and chip area, as well as avoiding LO crosstalk. A digital automatic gain control （AGC） loop is utilized to improve the receiver＇s robustness by optimizing the conversion gain of the analog-to-digital converter （ADC）. While drawing about 20 mA per channel from a 1.2 V supply, this RF receiver achieves a minimum noise figure （NF） of about 1.8 dB, an image rejection （IMR） of more than 35 dB, a maximum voltage gain of about 122 dB, a gain dynamic range of 82 dB, and an maximum input-referred 1 dB compression point of about -36.5 dBm with an active die area of 1.5 × 1.4 mm2 for the whole chip.展开更多
This paper presents a dual-band low noise amplifier for the receiver of a global navigation satellite system. The differences between single band and multi-band design methods are discussed. The relevant parameter ana...This paper presents a dual-band low noise amplifier for the receiver of a global navigation satellite system. The differences between single band and multi-band design methods are discussed. The relevant parameter analysis and the details of circuit design are presented. The test chip was implemented in a TSMC 0.18 μm 1P4M RF CMOS process. The LNA achieves a gain of 16.8 dB/18.9 dB on 1.27 GHz/1.575 GHz. The measured noise figure is around 1.5-1.7 dB on both bands. The LNA consumes less than 4.3 mA of current from a 1.8 V power supply. The measurement results show consistency with the design. And the LNA can fully satisfy the demands of the GNSS receiver.展开更多
In this paper, we continue our W-band photoinjector work. We discuss the production of a high brightness femtosecond bunch using our proposed W-band photoinjector under different parameters. The parameters of the prod...In this paper, we continue our W-band photoinjector work. We discuss the production of a high brightness femtosecond bunch using our proposed W-band photoinjector under different parameters. The parameters of the produced bunch are the energy of 1.2 MeV, the length of 60 fs, the peak current of 90 A, the normalized emittance of 0.4 mm mrad and the energy spread of 1.9%. Finally, we present some application examples of the proposed photoinjector.展开更多
基金Supported by National Science Foundation of China(51475438)Research Project Supported by Shanxi Scholarship Council of china(2014-055)Graduate student education innovation project in Shanxi province(2016BY124)
基金Supported by the Special Funds for Major State Basic Research Project of China under Grant No 2006CB6049, the National Natural Science Foundation of China under Grant Nos 6039072, 60476030, 60421003 and 60676057, the Ministry of Education of China （10416）, the Research Fund for the Doctoral Programme of Higher Education of China （20050284004）, and the Natural Science Foundation of Jiangsu Province （BK2005210 and BK2006126）.
文摘Indium nitride thin films are grown on sapphire substrates by metal-organic chemical vapour deposition （MOCVD） By employing three-step layer buffers, the mirror-like layers on two-inch sapphire wafers have been obtained. The structural, optical and electrical characteristics of InN are investigated by x-ray diffraction, scanning electron microscopy, atomic force microscopy, photoluminescence and infrared optical absorption. The photoluminescence and the absorption studies of the materials reveal a marked energy bandgap structure around 0.70eV at room temperature. The room-temperature Hall mobility and carrier concentration of the film are typically 939 cm^2 /Vs, and 3.9 × 1018cm^-3, respectively.
基金the Accelerator Laboratory of Tsinghua University for experiment supports
文摘A C-band RF pulse compressor is in development at SINAP It comprises of two resonant cavities,two mode convertors and a 3 dB power divider.TE_(0.1.15)mode is selected for obtaining higher quality factor Q_0 of the RF pulse compressor cavities,so that the power gain factor can be 3.2,which is supposed to multiply the RF power from 50 MW to 1 60 MW.In this paper,we report our work on C-band RF pulse compressor,namely the design simulation and cold test results.
基金Project supported by the Science and Technology Innovation Project for the Postgraduates of National University of Defense Technology
文摘A fully integrated dual-band RF receiver with a low-IF architecture is designed and implemented for GPS-L 1 and Compass-Bl in a 55-nm CMOS process. The receiver incorporates two independent IF channels with 2 or 4 MHz bandwidth to receive dual-band signals around 1.57 GHz respectively. By implementing a flexible frequency plan, the RF front-end and frequency synthesizer are shared for the dual-band operation to save power consumption and chip area, as well as avoiding LO crosstalk. A digital automatic gain control （AGC） loop is utilized to improve the receiver＇s robustness by optimizing the conversion gain of the analog-to-digital converter （ADC）. While drawing about 20 mA per channel from a 1.2 V supply, this RF receiver achieves a minimum noise figure （NF） of about 1.8 dB, an image rejection （IMR） of more than 35 dB, a maximum voltage gain of about 122 dB, a gain dynamic range of 82 dB, and an maximum input-referred 1 dB compression point of about -36.5 dBm with an active die area of 1.5 × 1.4 mm2 for the whole chip.
文摘This paper presents a dual-band low noise amplifier for the receiver of a global navigation satellite system. The differences between single band and multi-band design methods are discussed. The relevant parameter analysis and the details of circuit design are presented. The test chip was implemented in a TSMC 0.18 μm 1P4M RF CMOS process. The LNA achieves a gain of 16.8 dB/18.9 dB on 1.27 GHz/1.575 GHz. The measured noise figure is around 1.5-1.7 dB on both bands. The LNA consumes less than 4.3 mA of current from a 1.8 V power supply. The measurement results show consistency with the design. And the LNA can fully satisfy the demands of the GNSS receiver.
文摘In this paper, we continue our W-band photoinjector work. We discuss the production of a high brightness femtosecond bunch using our proposed W-band photoinjector under different parameters. The parameters of the produced bunch are the energy of 1.2 MeV, the length of 60 fs, the peak current of 90 A, the normalized emittance of 0.4 mm mrad and the energy spread of 1.9%. Finally, we present some application examples of the proposed photoinjector.
