A direct-conversion mixer with a DC-offset cancellation for WLAN

This paper presents a 5GHz double-balanced mixer with DC-offset cancellation circuit for direct-conversion receiver compliant with IEEE 802.11a wireless LAN standard. The analog feedback loop is used, to eliminate the DC-offset at the output of the double-balanced mixer. The test results show that the mixer with DC-offset cancellation circuit has voltage conversion gain of 9.5dB at 5.15GHz, noise figure of 13.5dB, IIP3 of 7.6 dBm, 1.73mV DC-offset voltage and 67mW power with 3.3-V power supply. The DC-offset cancellation circuit has less than 0.1mm(2) additional area and 0.3mW added power dissipation. The direct conversion WLAN receiver has been implemented in a 0.35 mu m SiGe BiCMOS technology.

A New Edge-Coupled Two-Terminal Double Heterojunction Phototransistor (ECTT-DHPT) and Its DC Characteristics

A new ECTT-DHPT with InGaAsP(lambda=1.55 mu m) as base and InGaAsP(lambda=1.3 mu m) as collector as well as waveguide was designed and fabricated, the DC characteristics reveal that the ECTT-DRPT can perform good optoelectronic mix operation and linear amplification operation by optically biased at two appropriate value respectively. Responsivity of more than 52A/W and dark current of 70nA (when V-ce=1V) were obtained.

A novel DC-DC charge pump circuit for passive RFID transponder

This paper presents a low-voltage, high performance charge pump circuit suitable for implementation in standard CMOS technologies. The proposed charge pump has been used as a part of the power supply section of fully integrated passive radio frequency identification(RFID) transponder IC, which has been implemented in a 0.35-um CMOS technology with embedded EEPROM offered by Chartered Semiconductor. The proposed DC/DC charge pump can generate stable output for RFID applications with low power dissipation and high pumping efficiency. The analytical model of the voltage multiplier, the comparison with other charge pumps, the simulation results, and the chip testing results are presented.

A direct-conversion mixer with DC-offset cancellation for IEEE 802.11a WLAN receiver

A DC-offset cancellation scheme in the 5GHz direct-conversion receiver compliant with IEEE 802.11a wireless LAN standard is described in this paper. It uses the analog feedback loop to eliminate the DC-offset at the output of the double-balanced mixer. The mixer has a simulation voltage conversion gain of IMB at 5.2GHz, noise figure of 9.67dB, IIP3 of 7.6dBm. The solution provides 39.1dB reduction according to the leakage value at LO and mixer load resistors, the additional noise figure added to mixer is less than 0.9dB, the added power dissipation is 0.1mW and was fabricated in 60GHz 0.35 mu m SiGe BiCMOS technology.

Electroabsorption-modulated DFB laser integrated with dual-waveguide spot-size converter - art. no. 60200N

A 1.55-mu m ridge DFB laser and electroabsorption modulator monolithically integrated with a buried-ridge-stripe dual-waveguide spot-size converter at the output port for low-loss coupling to a cleaved single-mode optical fiber was fabricated by means of selective area growth, quantum well intermixing and dual-core technologies. These devices exhibit threshold current of 28 mA, side mode suppression ratio of 38.0 dB, 3-dB modulation bandwidth of 12.0 GHz, modulator extinction ratios of 25.0 dB dc. The output beam divergence angles of the spot-size converter in the horizontal and vertical directions are as small as 8.0 degrees x 12.6 degrees, respectively, resulting in 3.2 dB coupling loss with a cleaved single-mode optical fiber.

Circuit design and simulation of a CMOS-based preamplifier for brain neural signals

A novel CMOS-based preamplifier for amplifying brain neural signal obtained by scalp electrodes in brain-computer interface (BCI) is presented in this paper. By means of constructing effective equivalent input circuit structure of the preamplifier, two capacitors of 5 pF are included to realize the DC suppression compared to conventional preamplifiers. Then this preamplifier is designed and simulated using the standard 0.6 mu m MOS process technology model parameters with a supply voltage of 5 volts. With differential input structures adopted, simulation results of the preamplifier show that the input impedance amounts to more than 2 Gohm with brain neural signal frequency of 0.5 Hz-100 Hz. The equivalent input noise voltage is 18 nV/Hz(1/2). The common mode rejection ratio (CMRR) of 112 dB and the open-loop differential gain of 90 dB are achieved.

A novel low-power input-independent MOS AC/DC charge pump

This paper presents a novel fully integrated MOS AC to DC charge pump with low power dissipation and stable output for RFID applications. To improve the input sensitivity, we replaced Schottky-diodes in conventional charge pumps with MOS diodes with zero threshold, which has less process defects and is thus more compatible with other circuits. The charge pump in a RFID transponder is implemented in a 0.35um CMOS technology with 0.24 sq mm die size. The analytical model of the charge pump and the simulation results are presented.

Design and Simulation Analysis of Spot-Size Converter in Silicon-On-Insulator

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HIV-1 C亚型密码子优化gp120负载人DC疫苗的构建及体外功能

目的构建HIV-1C亚型gp120负载人树突状细胞(dentriti ccell,DC)疫苗,并对其体外功能进行初步检测。方法利用Amaxa细胞核转染技术将pcDNA3.1-gp120质粒转染至人成熟DC,以Western blot检测gp120的表达。通过流式细胞仪检测DC表面共刺激分子的变化、混合淋巴细胞反应、CD8+T细胞表面活化分子CD25的表达及其分泌IFN-γ的变化。结果通过Western blot检测,gp120在DC中得到了正确表达。经流式细胞仪检测,DC表面分子CD80表达率由刺激前的33.34%上升至43.20%,CD86表达率由刺激前的60.08%上升至90.34%;负载gp120DC刺激淋巴细胞增殖率为86.72%;CD8+T细胞表面分子CD25表达率由刺激前的5.27%上升至74.21%,IFN-γ的表达率达37%。结论负载了HIV-1gp120的人树突状细胞能够显著刺激淋巴细胞的增殖、增强CD8+T细胞表面活化分子CD25表达以及促进CD8+T细胞分泌IFN-γ,为下一步DC治疗性疫苗的体内研究奠定基础。

MBE of GaN with DC-plasma source for nitrogen activation

In this paper we report on the first results of epitaxial growth of GaN layers on GaAs (100) substrates using a modified MBE system, equipped with a DC-plasma source for nitrogen activation in configuration of reverse magnetron at ultra-low pressures.

Design and Fabrication of Power Si1-xGex/Si Heterojunction Bipolar Transistor for Wireless Power Amplifier Applications

A multi-finger structure power SiGe HBT device （with an emitter area of about 166μm^2） is fabricated with very simple 2μm double-mesa technology. The DC current gain β is 144.25. The B-C junction breakdown voltage reaches 9V with a collector doping concentration of 1 × 10^17cm^-3 and a collector thickness of 400nm. Though our data are influenced by large additional RF probe pads, the device exhibits a maximum oscillation frequency fmax of 10.1GHz and a cut-off frequency fτ of 1.8GHz at a DC bias point of IC=10mA and VCE = 2.5V.

An Electroabsorption Modulator Monolithically Integrated with a Semiconductor Optical Amplifier and a Dual-Waveguide Spot-Size Converter

A semiconductor optical amplifier and electroabsorption modulator monolithically integrated with a spotsize converter input and output is fabricated by means of selective area growth,quantum well intermixing,and asymmetric twin waveguide technology. A 1550-1600nm lossless operation with a high DC extinction ratio of 25dB and more than 10GHz 3dB bandwidth are successfully achieved. The output beam divergence angles of the device in the horizontal and vertical directions are as small as 7.3°× 18.0°, respectively, resulting in a 3.0dB coupling loss with a cleaved single-mode optical fiber.

Monolithically Integrated Laser Diode and Electroabsorption Modulator with Dual-Waveguide Spot-Size Converter Output

A 1.60μm laser diode and electroabsorption modulator monolithically integrated with a novel dualwaveguide spot-size converter output for low-loss coupling to a cleaved single-mode optical fiber are demonstrated.The devices emit in a single transverse and quasi single longitudinal mode with an SMSR of 25.6dB. These devices exhibit a 3dB modulation bandwidth of 15. 0GHz, and modulator DC extinction ratios of 16.2dB. The output beam divergence angles of the spot-size converter in the horizontal and vertical directions are as small as 7. 3°× 18. 0°,respectively, resulting in a 3. 0dB coupling loss with a cleaved single-mode optical fiber.

射频能量AC/DC电荷泵的MOS实现研究

在射频能量AC/DC的能源转换实现研究中提出一种采用低阈值MOS管构成的高效电荷泵.新方案消除了现有的肖特基二极管高效电荷泵制作工艺特殊、批次性能不够一致的缺陷.分析表明,通过有机调整MOS管宽长比、器件电容、充电级数等设计参量,可以方便地满足不同的性能要求,实现集成制作方便、性能稳定的高效射频能量AC/DC型电荷泵.