共查询到20条相似文献,搜索用时 31 毫秒
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Zhenqiang Ma Ningyue Jiang 《Electron Devices, IEEE Transactions on》2005,52(2):248-255
The power gain difference, under different device stability conditions, between common-emitter (CE) and common-base (CB) bipolar junction transistors (BJT) is analyzed comprehensively. The analysis reveals that the CB configuration offers higher maximum available power gain than the CE configuration in the device's high operation frequency range, while the inverse relation holds in the very low frequency range. In the intermediate frequency range, the base resistance value, mainly affected by the base doping concentration, determines which configuration offers higher maximum stable power gain (MSG). These analyses have explicit implications on the operation configurations of SiGe heterojunction bipolar transistors (HBTs). Employing a typical doping profile of Si bipolar junction transistors with a trapezoidal Ge profile in SiGe HBTs usually results in a larger base resistance than the emitter resistance. For these devices, the CE configuration exhibits higher MSG than the CB configuration. Employing a higher base doping concentration than the emitter with a box-type Ge profile considerably reduces the base resistance and thus favors the CB configuration for power amplification in this frequency range. The analysis are quantitatively verified with simulation and measurement results from SiGe HBTs of representative Ge and base doping profiles. 相似文献
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An iteration scheme to calculate the base transit time (τb) for a given collector current density is developed in order to determine the optimal doping profile and Ge profile in the neutral base for minimizing the τb of SiGe HBTs under all levels of injection before the onset of the Kirk effect. We adopt a consistent set of SiGe transport parameters, tuned to measurement data, and include important effects such as the electric-field dependency of the diffusion coefficient and plasma-induced bandgap narrowing in our study. The scheme has been verified with simulation results reported in the literature. Our study shows that under both low and high injection, for a given Ge dose, intrinsic base resistance, and base concentration near the emitter, a retrograde doping profile with a trapezoidal Ge profile gives the minimum τb 相似文献
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Meng-Wei Hsieh Yue-Ming Hsin Kung-Hao Liang Yi-Jen Chan Denny Tang 《Electron Devices, IEEE Transactions on》2006,53(6):1452-1458
This paper investigates the temperature dependence (from 77 to 300 K) of dc, ac, and power characteristics for n-p-n SiGe heterojunction bipolar transistors (HBTs) with and without selectively implanted collector (SIC). In SiGe HBTs without SIC, the valance band discontinuity at the base-collector heterojunction induces a parasitic conduction band barrier while biasing at saturation region and high current operation at cryogenic temperatures. This parasitic conduction band barrier significantly reduces the current gain and cutoff frequency. For transistors biased with fixed collector current, the measured output power, power-added efficiency, and linearity at 2.4 GHz decrease significantly with decreasing operation temperatures. The temperature dependence of output power characteristic is analyzed by Kirk effect, current gain, and cutoff frequency at different temperatures. The parasitic conduction band barrier in SiGe HBTs with SIC is negligible, and thus the device achieves better power performance at cryogenic temperatures compared with that in SiGe HBT without SIC. 相似文献
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Niu G. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2005,93(9):1583-1597
This paper presents an overview of the physics, modeling, and circuit implications of RF broad-band noise, low-frequency noise, and oscillator phase noise in SiGe heterojunction bipolar transistor (HBT) RF technology. The ability to simultaneously achieve high cutoff frequency (f/sub T/), low base resistance (r/sub b/), and high current gain (/spl beta/) using Si processing underlies the low levels of low-frequency 1/f noise, RF noise, and phase noise of SiGe HBTs. We first examine the RF noise sources in SiGe HBTs and the RF noise parameters as a function of SiGe profile design, transistor biasing, sizing, and operating frequency, and then show a low-noise amplifier design example to bridge the gap between device and circuit level understandings. We then examine the low-frequency noise in SiGe HBTs and develop a methodology to determine the highest tolerable low-frequency 1/f noise for a given RF application. The upconversion of 1/f noise, base resistance thermal noise, and shot noises to phase noise is examined using circuit simulations, which show that the phase noise corner frequency in SiGe HBT oscillators is typically much smaller than the 1/f corner frequency measured under dc biasing. The implications of SiGe profile design, transistor sizing, biasing, and technology scaling are examined for all three types of noises. 相似文献
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Qingqing Liang Cressler J.D. Guofu Niu Malladi R.M. Newton K. Harame D.L. 《Electron Devices, IEEE Transactions on》2002,49(10):1807-1813
A physics-based cutoff frequency model considering high-injection heterojunction barrier effects in SiGe HBTs is derived. Compared with other compact modeling approaches, the present model accurately captures the cutoff frequency behavior at very high current densities for SiGe HBTs with deep Si-SiGe heterojunctions. The model also offers better insight into the charge density distribution under Kirk and barrier effect in SiGe HBTs. 相似文献
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Washio K. Ohue E. Oda K. Hayami R. Tanabe M. Shimamoto H. 《Electron Devices, IEEE Transactions on》2002,49(10):1755-1760
Characteristics related to the emitter-base junction of self-aligned selective-epitaxial-growth SiGe heterojunction bipolar transistors (HBTs) were optimized for use with a highly-doped base. The thickness of the Si-cap layer affected both the emitter-base junction concentration and space-charge width, so the dc and ac characteristics of the SiGe HBTs were in turn dependent on this thickness. With a 4/spl times/10/sup 19/-cm/sup -3/ boron-doped base, a 131-GHz cutoff frequency and ECL gate-delay time of 5.4 ps were achieved for the optimized SiGe HBTs. A static frequency divider with a maximum operating frequency of 72.2 GHz and a dynamic frequency divider with a maximum operating frequency of 92.4 GHz were developed for optical-fiber link and millimeter-wave communication systems of the future. 相似文献
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A new analytical model for the base current of Si/SiGe/Si heterojunction bipolar transistors(HBTs) has been developed. This model includes the hole injection current from the base to the emitter, and the recombination components in the space charge region(SCR) and the neutral base. Distinctly different from other models, this model includes the following effects on each base current component by using the boundary condition of the excess minority carrier concentration at SCR boundaries: the first is the effect of the parasitic potential barrier which is formed at the Si/SiGe collector-base heterojunction due to the dopant outdlffusion from the SiGe base to the adjacent Si collector, and the second is the Ge composition grading effect. The effectiveness of this model is confirmed by comparing the calculated result with the measured plot of the base current vs. the collector-base bias voltage for the ungraded HBT. The decreasing base current with the increasing the collector-base reverse bias voltage is successfully explained by this model without assuming the short-lifetime region close to the SiGe/Si collector-base junction, where a complete absence of dislocations is confirmed by transmission electron microscopy (TEM)[1]. The recombination component in the neutral base region is shown to dominate other components even for HBTs with a thin base, due to the increased carrier storage in the vicinity of the parasitic potential barrier at collector-base heterojunction. 相似文献
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Our basic approach is to develop a symmetrical design with equal delay times for collector, base and the total load to simulate the high frequency behaviour of SiGe heterobipolar transistors (HBTs). On this base we have investigated the feasibility of SiGe HBTs with transit frequencies fT above 200 GHz. A symmetrical design reaching fT=208 GHz is presented. The dependence of the high frequency behaviour on Ge content and vertical transistor design is shown. Critical parameters like the maximum current density and the breakthrough voltage are considered. An analytical model is compared to numerical simulations and experimental data. 相似文献
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对SiGe HBT低频噪声的各噪声源进行了较全面的分析,据此建立了SPICE噪声等效电路模型,进一步用PSPICE软件对SiGe HBT的低频噪声特性进行了仿真模拟.研究了频率、基极电阻、工作电流和温度等因素对低频噪声的影响.模拟结果表明,相较于Si BJT和GaAs HBT,SiGe HBT具有更好的低频噪声特性;在低频范围内,可通过减小基极电阻、减小工作电流密度或减小发射极面积、降低器件的工作温度等措施来有效改善SiGe HBT的低频噪声特性.所得结果对SiGe HBT的设计和应用有重要意义. 相似文献
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A current gain cutoff frequency fT of 508 GHz is reported for a SiGe heterojunction bipolar transistor (HBT) operating at 40 K. This 63% increase over the 311 GHz value measured at room temperature results from the overall decrease of the transit and charging times. Two HBTs are compared to highlight the importance of the topology of the HBT to reach maximum performances. 相似文献
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Lombardo S. Pinto A. Raineri V. Ward P. La Rosa G. Privitera G. Campisano S.U. 《Electron Device Letters, IEEE》1996,17(10):485-487
We have fabricated n-p-n, Si/Ge2Si1-x heterojunction bipolar transistors (HBTs) with the GexSi1-x base formed by high-dose Ge implantation followed by solid phase epitaxy. The fabrication technology is a standard self-aligned, double polysilicon process scheme for Si with the addition of the high-dose Ge implantation. The transistors are characterized by a 60 mn-wide neutral base with a Ge concentration peak of ≈8 at.% at the base-collector junction. The HBTs show good electrical characteristics and compared to Si homojunction transistors show lower base resistance, larger values of current gain, and a lower emitter-to-collector transit time 相似文献
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This work quantifies neutral base recombination in UHV/CVD SiGe heterojunction bipolar transistors (HBTs) using calibrated two-dimensional (2-D) simulation. The simulated collector-base conductance through neutral base recombination (NBR) modulation is far below the experimentally observed values, and hence does not explain the measured output resistance degradation under forced-IB operation. In spite of the output resistance degradation, these UHV/CVD SiGe HBTs have approximately the same base current as the silicon control, and hence higher current gain. Based on the observation of the majority carrier concentration limited recombination in the CB junction depletion layer, as opposed to the minority carrier concentration limited recombination in the neutral base, local presence of traps in the CB junction depletion layer is suggested. This explains the measured CB conductance modulation and the related output resistance degradation without compromising the current gain. Numerical simulations using traps locally introduced into the CB junctions successfully reproduced the measured collector-base conductance from simulation without appreciable degradation in current gain 相似文献
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DeLuca P.M. Lutz C.R. Welser R.E. Chi T.Y. Huang E.K. Welty R.J. Asbeck P.M. 《Electron Device Letters, IEEE》2002,23(10):582-584
InGaP/GaInAsN double heterojunction bipolar transistors (HBTs) with compositionally graded bases are presented which exhibit superior dc and radio frequency performance. Reducing the average base layer energy gap and optimizing the emitter-base (e-b) and base-collector (b-c) heterojunctions leads to a 100-mV reduction in the turn-on voltage compared to a baseline InGaP/GaAs process. Simultaneously grading the base layer energy band-gap results in over a 66% improvement in the dc current gain and up to a 35% increase in the unity gain cutoff frequency. DC current gains as high as 250 and cutoff frequencies of 70 GHz are demonstrated. In addition, the InGaP/GaInAsN DHBT structure significantly reduces the common emitter offset and knee voltages, as well as improves the dc current gain temperature stability relative to standard InGaP/GaAs HBTs. 相似文献
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Jagannathan B. Khater M. Pagette F. Rieh J.-S. Angell D. Chen H. Florkey J. Golan F. Greenberg D.R. Groves R. Jeng S.J. Johnson J. Mengistu E. Schonenberg K.T. Schnabel C.M. Smith P. Stricker A. Ahlgren D. Freeman G. Stein K. Subbanna S. 《Electron Device Letters, IEEE》2002,23(5):258-260
This paper reports on SiGe NPN HBTs with unity gain cutoff frequency (fT) of 207 GHz and an fMAX extrapolated from Mason's unilateral gain of 285 GHz. fMAX extrapolated from maximum available gain is 194 GHz. Transistors sized 0.12×2.5 μm2 have these characteristics at a linear current of 1.0 mA/μm (8.3 mA/μm2). Smaller transistors (0.12×0.5 μm2) have an fT of 180 GHz at 800 μA current. The devices have a pinched base sheet resistance of 2.5 kΩ/sq. and an open-base breakdown voltage BVCEO of 1.7 V. The improved performance is a result of a new self-aligned device structure that minimizes parasitic resistance and capacitance without affecting fT at small lateral dimensions 相似文献