基于0.18μm SiGe BiCMOS工艺的25Gb/s宽带可变增益放大器

介绍了一种基于0.18 μm SiGe BiCMOS工艺的,可应用于高速通信的25 Gb/s可变增益放大器(VGA).该放大器由核心电路、输出缓冲器和偏置电路组成,核心电路采用改进型Gilbert结构,增大了电路的增益动态范围;同时采用电感峰化技术克服大寄生电容来实现宽带特性.后仿真结果表明,该可变增益放大器的最大增益为20.15 dB,-3 dB带宽(BW)为26.8 GHz,可支持高达25 Gb/s的数据速率,在3.3 V电源电压下的功耗为26.4 mW,芯片大小为1 120 μm×1 167 μm.     

基于802.11a标准的CMOS正交调制器和上变频器

采用0.18μm CMOS工艺,设计并实现了应用于WLAN IEEE 802.11a的正交调制器和上变频器.正交调制器在传统的Gilbert单元基础上,采用负反馈跨导放大器来提高线性度;上变频器采用LC谐振网络作混频器负载来提高增益和电压输出摆幅.测试结果表明,在1.8V电源电压下,谐振频率点的1dB压缩点P1dB为-3.6dBm,功率转换增益为-3.6dB,电流消耗大约45.8mA.     

Coding‐theoretic constructions for (t,m,s)‐nets and ordered orthogonal arrays

(t,m,s)‐nets are point sets in Euclidean s‐space satisfying certain uniformity conditions, for use in numerical integration. They can be equivalently described in terms of ordered orthogonal arrays, a class of finite geometrical structures generalizing orthogonal arrays. This establishes a link between quasi‐Monte Carlo methods and coding theory. The ambient space is a metric space generalizing the Hamming space of coding theory. We denote it by NRT space (named after Niederreiter, Rosenbloom and Tsfasman). Our main results are generalizations of coding‐theoretic constructions from Hamming space to NRT space. These comprise a version of the Gilbert‐Varshamov bound, the (u,u+υ)‐construction and concatenation. We present a table of the best known parameters of q‐ary (t,m,s)‐nets for qε{2,3,4,5} and dimension m≤50. © 2002 Wiley Periodicals, Inc. J Combin Designs 10: 403–418, 2002; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/jcd.10015     

Fabrication Method,Ferromagnetic Resonance Spectroscopy and Spintronics Devices Based on the Organic-Based Ferrimagnet Vanadium Tetracyanoethylene

Organic-based magnetic materials have been used for spintronic device applications as electrodes of spin aligned carriers and spin-pumping substrates. Their advantages over more traditional inorganic magnets include reduced magnetic damping and lower fabrication costs. Vanadium tetracyanoethylene, V[TCNE]_x (x ≈ 2), is an organic-based ferrimagnet with an above room-temperature magnetic order temperature (T_c ≈ 400 K). V[TCNE]_x has deposition flexibility and can be grown on a variety of substrates via low-temperature chemical vapor deposition (CVD). A systematic study of V[TCNE]_x thin-film CVD parameters to achieve optimal film quality, reproducibility, and excellent magnetic properties is reported. This is assessed by broadband ferromagnetic resonance (FMR) that shows most narrow linewidth of ≈1.5 Gauss and an extremely low Gilbert damping coefficient. The neat V[TCNE]_x films are shown to be efficient spin injectors via spin pumping into an adjacent platinum layer. Also, under an optimized FMR linewidth, the V[TCNE]_x films exhibit Fano-type resonance with a continuum broadband absorption in the microwave range, which can be readily tuned by the microwave frequency.     

Weak martingale solutions to the stochastic Landau–Lifshitz–Gilbert equation with multi-dimensional noise via a convergent finite-element scheme

We propose an unconditionally convergent linear finite element scheme for the stochastic Landau–Lifshitz–Gilbert (LLG) equation with multi-dimensional noise. By using the Doss–Sussmann technique, we first transform the stochastic LLG equation into a partial differential equation that depends on the solution of the auxiliary equation for the diffusion part. The resulting equation has solutions absolutely continuous with respect to time. We then propose a convergent $\theta$-linear scheme for the numerical solution of the reformulated equation. As a consequence, we are able to show the existence of weak martingale solutions to the stochastic LLG equation.     

Spin pumping at the Co2FeAl0.5Si0.5/Pt interface

Spin pumping at the Co2FeAl0.5Si0.5/Pt and Pt/Co2FeAl0.5Si0.5 interfaces has been studied by ferromagnetic resonance technology(FMR). The spin mixing conductance of the Co2FeAl0.5Si0.5/Pt and Pt/Co2FeAl0.5Si0.5 interfaces was determined to be 3.7×1019m 2and 2.1×1019m 2 by comparing the Gilbert damping in a Co2FeAl0.5Si0.5single film, Co2FeAl0.5Si0.5/Pt bilayer film and a Pt/Co2FeAl0.5Si0.5/Pt trilayer film. Spin pumping is more efficient in the Co2FeAl0.5Si0.5/Pt bilayer film than in permalloy/Pt bilayer film.     

基于CMOS工艺的改进型电流注入混频器

设计了一种改进型电流注入混频器.通过在吉尔伯特混频器电路的本振开关管源极引入电感形成谐振电路,消除了开关管源极寄生电容的影响,降低了混频器电路的闪烁噪声,增大了混频器电路的增益.混频器电路的设计采用SMIC 0.35 μm CMOS 工艺库,本振功率为-3 dBm.仿真结果表明,与改进前的混频器电路相比,当本振功率为-3 dBm时,改进型电流注入混频器电路的增益提高了1.76 dB,IIP3提高2.1 dBm,噪声系数降低了0.5 dB.     

80 Gb/s 2 : 1 multiplexer in 0.13-μm SiGe BiCMOS technology

This work presents an ultra-high speed 2 : 1 multiplexer (MUX) in a SiGe BiCMOS technology with fT = 103 GHz. To boost the operating speed, the system scheme is optimized including a 2 : 1 selector circuit directly driving an external 50 Ω load, and two wide-band data buffers and one clock buffer in the input stage. The chip exhibited an open eye at 80 Gb/s with a 160 mV single-ended voltage swing.