Mechanism of anomalous recovery in advanced SiGe bipolar transistors after low dose rate irradiation for very high total doses

The possible physical mechanism of the anomalous recovery effect in SiGe bipolar transistors is described. The qualitative analysis of saturated oxide trapped charge and interface trap densities at very high total doses as a function of dose rate affords an explain of decreasing excess base current and increasing current gain during further low dose rate irradiation.     

Numerical investigation of a double-junction a:SiGe thin-film solar cell including the multi-trench region

We present a new approach based on the multi-trench technique to improve the electrical performances, which are the fill factor and the electrical efficiency. The key idea behind this approach is to introduce a new multi-trench region in the intrinsic layer, in order to modulate the total resistance of the solar cell. Based on 2-D numerical investigation and optimization of amorphous SiGe double-junction (a-Si:H/a-SiGe:H) thin film solar cells, in the present paper numerical models of electrical and optical parameters are developed to explain the impact of the multi-trench technique on the improvement of the double-junction solar cell electrical behavior for high performance photovoltaic applications. In this context, electrical characteristics of the proposed design are analyzed and compared with conventional amorphous silicon double-junction thin-film solar cells.     

First principles calculation of the opto-electronic properties of (110) growth axis SiGe superlattices

Using two versions of the first principles full potential linear muffin-tin orbitals method (FPLMTO) which enable an accurate treatment of the interstitial regions, the electronic and optical properties of (110) growth axis Si/SiGe superlattices are investigated. A comparative study with (001) growth axis superlattices is made. In particular, it is found that the bottom of the conduction band (CB) is closer to Γ$\Gamma$ in the (110) system but the optical activity is not enhanced. Furthermore, the absorption spectra of the superlattices are calculated and are found to be quite different from those of bulk Si and Ge but fairly close to their average.     

一种低温漂BiCMOS带隙基准电压源的设计

文章介绍了一种低温漂的BiCMOS带隙基准电压源.基于特许半导体(Chartered)0.35 μm BiCMOS工艺,采用Brokaw带隙基准电压源结构,通过一级温度补偿技术,设计得到了一种在-40℃到 85℃的温度变化范围内温度系数为15.2×10-6/℃,输出电压为2.5 V±0.002 V的带隙基准电压源电路.±20%的电源电压变化情况下,输出电压变化为2.2 mV,电源电压抑制比为60 dB.5 V电源电压下功耗为1.19 mW.具有良好的电源抑制能力.     

一种BiCMOS过温保护电路

在分析现有过温保护电路的基础上,针对它们电路结构复杂、功耗较高、工作电压高等缺点提出了一种用于集成电路内部的采用BiCMOS工艺的过温保护电路,电路结构简单、功耗较低、工作电压低、抗干扰能力强,对温度的迟滞特性避免了热振荡对芯片带来的危害。采用0．6μm BiCMOS工艺的HSPICE仿真结果表明,该电路对因电源电压、和工艺参数变化而引起的温度迟滞特性的漂移具有很强的抑制能力。     

一种新型高速低功耗BiCMOS分频器

本文设计了一种基于BiCMOS技术的分频器,结合了双极（Bipolar）和CMOS技术的优点。作为分频器的基本单元,锁存器的工作速度直接影响了分频器的性能。通过分离跟踪差分对与交叉耦合对,并减小后者的偏置电流可以提高锁存器的工作速度。同时,合并两个锁存器的跟踪差分对可以减小分频器的功耗。采用0．8μm BiCMOS模型在Cadence SPECTRE中仿真,可以得到这种新型高速低功耗分频器的工作频率上限可以达到2．4GHz,功耗为-1．61dBm。     

一款2 G/s采样率20 GHz带宽主从式跟踪保持电路设计研究

设计了一款全差分、20 GHz带宽主从式跟踪保持芯片(MS-THA)。该芯片采样率为2 G/s,工作带宽大于20 GHz,采用0.13μm SiGe BiCMOS工艺实现。该芯片采用传统的开关发射极跟随器(SEF)作为跟踪保持核心电路,Cherryhooper电路作为输入缓冲和输出缓冲的带宽增强核心电路,并利用交叉反馈电容抑制馈通。为了验证上述电路的有效性,设计了一个单级THA电路,测试结果为MS-THA电路提供了足够的支持。在单电源+3.3 V供电、输入直流电平为0 V,2 G/s采样率以及-3 dBm输入信号功率条件下,获得的单端输出无杂散动态范围小于-23.5 dB,总功耗约为300 mW。     

可见光LED的进展——超高亮度LED及应用(二)

可见光ＬＥＤ的进展——超高亮度ＬＥＤ及应用（二）张万生梁春广（电子工业部第十三研究所，石家庄，０５００５１）４超高亮度发光管的发展［９～１４］４．１ＩｎＧａＡｌＰＤＨＬＥＤ发光强度达到坎德拉级发光管的高亮度化一直是半导体材料和器件的前沿课题之一，超高...     

低噪声X波段再生式分频组件研究

采用低噪声再生式分频技术,设计了低噪声X波段再生式分频组件。首先研究讨论了再生式分频的噪声理论,分析了有源器件对于近载波噪声和远载波噪声性能的影响。接着设计制作了两级锗硅HBT放大器、混频器、微带结构带通、带阻滤波器和功率分配器,其中低1/f锗硅HBT放大器首次应用于低噪声再生式分频器的设计。最后对分频组件进行了测试,测试结果良好,在近载波相位噪声性能改善6dB;在远载波白噪声段,噪声小于-165dBc/Hz。测试结果与理论计算结果吻合良好,达到了低噪声的设计要求。     

UWB LNA的增益平坦化及稳定性的反馈技术

从异质结晶体管(HBT)的小信号模型着手,得到了几种不同反馈形式下HBT的S参数解析表达式。通过对比不同反馈形式的仿真结果,分析了各种反馈形式对S参数的影响,并着重研究了反馈技术对电路稳定性以及对超宽带低噪声放大器(UWB LNA)增益平坦度的影响。结果表明,采用串联电阻和电感或并联电阻和电容的电抗性负反馈,可以使S21的幅度随着频率的增大而逐渐上升,从而补偿了晶体管本身高频增益的下降,同时,也提高了整个电路的稳定性。采用这种反馈结构,设计了一款3～10 GHz超宽带低噪声放大器。仿真结果表明,该放大器在整个频带范围内无条件稳定,传输增益较高,增益平坦度较好,噪声系数较低,是一款无条件稳定并有着较好增益平坦度的超宽带低噪声放大器。