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SiGe technology is sincerely challenging III/V and II/VI ...

SiGe technology is sincerely challenging III/V and II/VI

technologies in the realm of high frequency electronics

applications, for example optical fibre and mobile

communications. In this paper a model of SiGe HBT with uniform

impurity doping in the base for high frequency application is

studied. The high frequency parameters are extracted with the

help of simulated Z- and Y- parameters of two port equivalent

circuits of the proposed SiGe HBT device and electrical

parameters are calculated with the help of small-signal analysis of

projected device. Later, the topics are also involved in

instantaneous investigation of effect of Ge concentration on

various electrical as well as HF parameters of this SiGe HBT. This

method is validated by the examination of certain linear relations

of device frequency behaviour as forecasted by the analogous

theoretical analysis. Further, the precision of our method is

validated by simulated S–parameter plots. The device

characteristics of the proposed model are found much advanced

to those of III-V semiconductor devices. These results have been

also validated using a viable numerical device simulator ATLAS

from Silvaco International

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- 1. Journal of Electrical and Control Engineering JECE Electrical Parameter Extraction & Modeling of Si1-xGex HBT for HF Applications Pradeep Kumar#1, R. K. Chauhan*2 #1 Department of ECE, Ideal Institute of Management & Technology, Ghaziabad, INDIA *2 Department of ECE, M.M.M. Engineering College, Gorakhpur, INDIA 1 pradeep.hitesh@gmail.com; 2rkchauhan27@gmail.comAbstract-SiGe technology is sincerely challenging III/V and II/VI submillimeter wave transceiver designs, where progressivetechnologies in the realm of high frequency electronics improvements in transistor bandwidth enable the evolution ofapplications, for example optical fibre and mobile communications and radars ICs operating to higher frequencies.communications. In this paper a model of SiGe HBT with uniform In addition, faster transistors enable the wider band mixed-impurity doping in the base for high frequency application is signal ICs (e.g., analog-to-digital converters, digital-to-analogstudied. The high frequency parameters are extracted with the converters, etc.) that improve the resolution of radars andhelp of simulated Z- and Y- parameters of two port equivalent communications systems [2]. Meanwhile, several hundred GHzcircuits of the proposed SiGe HBT device and electrical applications are starting to expand from the initial nicheparameters are calculated with the help of small-signal analysis ofprojected device. Later, the topics are also involved in markets of Earth, planetary, and space science to the largerinstantaneous investigation of effect of Ge concentration on commercial markets in biomedical imaging, non-metallicvarious electrical as well as HF parameters of this SiGe HBT. This object detection, quality control, and secure communications.method is validated by the examination of certain linear relations For the meantime, application fields related to THzof device frequency behaviour as forecasted by the analogous frequency range are expanded from the initial markets oftheoretical analysis. Further, the precision of our method is planetary, earth and space science [3]–[6] to a biggervalidated by simulated S–parameter plots. The device commercial markets in biomedical imaging, quality control,characteristics of the proposed model are found much advanced secure communications, and non-metallic object detection [7].to those of III-V semiconductor devices. These results have beenalso validated using a viable numerical device simulator ATLAS In present time, THz sensors are prepared from heterodynefrom Silvaco International. semiconductors and novel direct detectors such as quantum-dot single-photon detectors and schottky diodes. THz sources are Keywords-Silicon; SiGe；HBT; Ge Concentration; Small-signal usually achieved through several optical techniques [8]. But,Analysis; Intrinsic Parameters deficient existing oscillators and amplifiers made of active semiconductor transistors become a bottleneck. Furthermore, I. INTRODUCTION improved bandwidth in a transistor normally associates well During the past several years, SiGe HBT technology has with improved RF performance e.g. higher gain and lowerentered the global semiconductor electronics market. Now noise. Thus THz transistors can significantly widen the designSiGe HBT technologies are being increasingly deployed in limitations of existing performance-constrained lowerNorth America, Europe (such as dot5 project) for a wide frequency (RF through millimeter-wave) circuits and systemsvariety of communications circuit applications such as cellular [9][10]. An ample range of space electronics platforms (forphones, in the microwave region and the semiconductor instance analog, digital, and RF) are designed to operate atindustry investing heavily to improve the performance of space and planetary ambient conditions which can be enabledsilicon devices for high frequency applications. The by high-bandwidth bandgap-engineered transistors withoutmultibillion semiconductor industry is rapidly using bulky and power-hungry heating units [11].devices/transistors working in several GHz regions and ispushing to demonstrate useful solid-state transistors, and The purpose of this work is to search physical issues of theresultant circuits built from them, capable of operating near the device modelling of small-signal equivalent circuits for SiGeTHz regime. There are two major driving forces for SiGe solid- HBTs with uniform impurity doping in the base. During thestate devices: 1) high frequency communications and radars last few years, various methods for parameter extraction andand 2) various niche THz applications. Recent research has HBT high frequency small-signal modelling have beenfocused on expanding THz options from two-terminal devices published and developed [12] – [16]. In 2002, Basaran and(e.g., Schottky diodes) to three-terminal devices (transistors) Berroth presented their model to extract the device parametersfor both application areas. In high-frequency communications but it is not a simple and complete extraction method [17]. Forand radars, higher bandwidth transistors are desirable in a ease of extraction process, a simple and accurate method isnumber of applications. Optical fiber communications require depicted in this proposed model. This device is simulated inactive amplifiers in decision circuits, multiplexers, and phase- ATLAS device simulator. In this process Y-, Z- and S-lock loops operating at 100-GHz clock frequency and above parameters are extracted directly by ATLAS. Then the[1]. electrical parameters are calculated with the help of above parameters and small-signal equivalent circuit analysis. In this High current-gain and power-gain frequencies (fT and fmax) work, a numerical simulation results are preferred instead ofare also demanded in microwave, millimeter-wave, and JECE Vol. 2 No. 2, 2012 PP. 27-34 ○2011-2012 World Academic Publishing C 27
- 2. Journal of Electrical and Control Engineering JECEreal measurement results for avoiding the interference fromextrinsic parts in the calculation of small-signal parameters. In this paper, we model the electrical as well as HFparameters and calculate the unity current-gain frequency andunity power-gain frequency for high speed applications of n-p-n SiGe HBT with uniform impurity doping in the base with thehelp of directly extracted Z-, Y-, and S-parameters. At thesame time the effect of Ge concentration is investigated forabove device parameters. With this impulse, we address small-signal HF modelling in the second section. In the third section,the simulation and calculated results are discussed. At last, weconcluded with general protrusions and remarks in section-IV. II. SMALL-SIGNAL HF MODELING In this section, a simple, accurate, and novel extractionmethod is presented for discussing the transistor HFperformance along with procedures to find out the parameters Fig. 1 A small-signal Π equivalent circuit of an HBT device (a) containsof SiGe HBT by means of small-signal π-topology equivalent intrinsic and extrinsic circuit elements. The intrinsic elements (b) can becircuits of this HBT with uniform impurity doping in the base. determined from the admittance parameters of the device at a number of different bias pointsThe algorithm is useful for extracting both intrinsic as well asextrinsic elements. The conventional methods derived from The maximum stable gain is calculated by y21 and y12 assimple bias measurements work very sound when we [18],determine formerly the extrinsic elements of the HBT. Throughdifferent procedures for example DC or optimization can be y 21 (1)used for this strategy [18]. MSG y 12 It is often very hard to accurately determine the values of And the maximum available gain is extracted as [18],parasitic elements of the HBT because the typical DC and cut-off techniques present poor performance for Silicon y 21 (2) MAG (k k 2 1)Germanium HBT devices. So an innovative procedure has been y12developed to circumvent this problem. In this technique only Where k is ‘Rollett stability factor’ and extracted by thisscattering (S)-parameters at different biases are measured. For equation as [18],fitting the measured S-parameters appropriately, linear modelsby way of π-topology have been experienced. For simplicity, 2 Re( y 11) Re( y 22 ) Re( y 12 y 21) k (3)we ignored emitter resistance, the collector resistance, togetherwith the output resistance due to early effect [19]. y 12 y 21 Mansion’s gain is obtained by the following equation as Using ATLAS, the S-parameters which are obtained from [18],AC analysis are simply converted into Y-, Z- or H-parameters.Various Power Gains for example MAG, MSG, as well as 2MAUG (are used for such analysis. Furthermore, a figure-of- y 12 y 21 (4) U merit that has been used extensively such characterization is 4[Re( y 11) Re( y 22 ) Re( y 12 ) Re( y 21)]maximum stable gain. At high frequencies these quantities are The maximum available unilateral gain is calculated by thiscalculated from the measured small-signal scattering equation as [18],parameters due to simplicity of measurement [18]. 2 y 21 (5) MAUG 4 Re( y11) Re( y 22) We get the MAG when both input and output are concurrently conjugate matched. When k > 1, the device is unconditionally stable and MAG exists. It is obvious from Equations (4) and (5), if the device is unilateral (y12 = 0) then U equals to MAUG. The MAG equals to MSG and vice-versa when the device is unconditionally stable. Maximum frequency at which MSG becomes unity is frequently termed as fmax. As power gain with no impedance transformation is achieved by common-emitter microwave transistors. This is the reason why these transistors may comprise useful gain when inserted into a system with 50 Ω [18]. For this model, MSG is called a figure of merit. This device is unconditionally stable here. JECE Vol. 2 No. 2, 2012 PP. 27-34 ○2011-2012 World Academic Publishing C 28
- 3. Journal of Electrical and Control Engineering JECEA. Frequency Response The collector-emitter junction resistance is obtained by the In most HF and millimeter wave circuit applications, it is equation as follows [21],the frequency response of transistor that confines system 1performance. One of the imperative figures of merit in this R CE Re Re context is the unity–gain cutoff frequency (fT), which is given Y 12 Y 22 (12)as [20] 1 1 The collector-emitter junction resistance is expressed by the f T [ (C eb C Cb) b c e] equation as follows [21], gm (6) 1 R BE Re Re Y 11 Y 12 (13) Where and are the EB and CB capacitances, gm is In this method CBE are intrinsic junction capacitances andthe transconductance and , , are the base, emitter, and RBC, RCE and RBE are intrinsic junction resistances.collector transit times, respectively. The transistor cut-off C. Calculation of Extrinsic Parametersfrequency is thus a valuable metric for evaluating different As the device dimension shrinks, the parameters RB andtechnologies. usually limits the maximum transistor in the parasitic capacitances start to measure the high frequencyusual Si BJT’s,. behaviour of the device and have to be taken into account in the equivalent circuit to improve the transistor model accuracy In the context of HF and millimetre-wave applications, the in the broad frequency range from Y parameters under theunity power-gain frequency ( ), or maximum oscillation reverse-bias condition.frequency is a more relevant figure of merit because The extrinsic resistance is obtained by the equation asdepends not only on the intrinsic transistor performance ( ) follows [18],but also the parasitics of the device, as [20] R B Z 11 Z 12 (14) The base-collector junction capacitance can be measured as fT [17], f max 8 C Cb R B I m Y 12 (7) C BC (15) Where RB is the base resistance and CBC is the base- And the base-emitter junction capacitances can becollector junction capacitance. Thus from Equation (7) it is measured as [17],clear that for the higher value of fmax, the value of base-collector junction capacitance and base resistance should be I m Y 12 Y 11 lower. So the cut-off frequency fT increases as transit time C BE (16)decreases which in turn affect the fmax.B. Calculation of Intrinsic Parameters III. RESULTS & DISCUSSION The intrinsic and extrinsic parameters in Fig. 1 can be On the basis of above model and method the values ofextracted by the following method: the base-emitter junction many performance parameters such as electrical parameterscapacitance is calculated by the equation as follows [21], and device high frequency parameters which include various intrinsic as well as extrinsic elements, current-gain (β), I m Y 11 I m Y 12 collector current, base resistance, junction capacitance, C BE maximum oscillation frequency fmax, unity current-gain i (8) frequency (i.e. cut-off frequency) fT, are calculated for n-p-n The base-collector junction capacitance is expressed by the SiGe HBT with uniform impurity doping in the base. Alongequation as follows [21], with this effort, an investigation is also performed regarding the effect of Ge concentration on these parameters. For this I m Y 12 C BC purpose we find out the value of above parameters at different i (9) Ge concentrations. The HBT considered in this paper has the The base-collector junction capacitance is expressed by the base width of 0.1µm. Average Ge concentration in this baseequation as follows [21], region considered in our calculations is varied from 10%-28% as higher than this are not supported by present epitaxial I m Y 22 I m Y 12 technologies and beyond it the improvement associated with C CE Ge seizes may be due to lattice constant mismatch [18]. i (10) ATLAS simulation of SiGe HBT is performed to prove The base-collector junction capacitance is calculated by the precision. All important physical effects, such as impactequation as follows [21], ionization (II) is appropriately modeled and accounted for the 1 simulation for obtaining admirable pact with characteristics. R BC Re The impact ionization results in a strong improvement of Y 12 (11) collector-current. AC simulation needs apposite DC calibration JECE Vol. 2 No. 2, 2012 PP. 27-34 ○2011-2012 World Academic Publishing C 29
- 4. Journal of Electrical and Control Engineering JECEwhich is an important prerequisite for it [18]. For this shows the intrinsic as well as extrinsic element of HBT whilesimulation, it is compulsory to take the complete device the part (b) intrinsic part only. The intrinsic elements (b) can becomposition into account with the aim of considering the determined from extracted Y- parameters of the device at acapacitance between substrate and collector (CCS) as well as number of different bias points.capacitance between base and collector (CBC).A. Determination Of Collector Current, Base Current And Gain Enhancement A very important consequence of adding Ge into the baseof a transistor is its effect on the collector current density (Jc).With Ge in the base, electron injection at the emitter basejunction is made easier, and thus more charge can flow fromthe emitter to the collector with a resultant increase in Jc. Also,because of the Ge-induced band offset, there is a decrease inintrinsic carrier density in the base which also increases Jc [3].As the emitter regions of both a Si BJT and a SiGe, HBT areessentially the same, implying an identical base current density(JB). The net result is that adding Ge increases the current gainof the transistor (β = JC/ JB) as in Figure 4. In testing, themaximum current-gain is found about 912 at 28% Ge content. Fig. 3 Effect of germanium content on collector current Fig. 4 Effect of Ge concentration over current-gain Fig. 2 Collector & Base currents of SiGe HBT This plot indicates that the important DC consequence ofadding Ge into the base, however, lies with the collectorcurrent density. Figure 2 shows the variation of IC & IB ofSiGe HBT at various bias points. Figure 3 shows that effect ofGermanium content on collector current and it is found that theIC increases as the concentration of Ge increases. We alsoinvestigated that the collector current is maximum at 28% Geconcentration and after this Ge concentration it does not followthe rule due to lattice constant mismatch. The simulated SiGe HBT is shown in Figure 5.B. Determination Of Intrinsic & Extrinsic Parameters The intrinsic and extrinsic parameters are determined byFigure 1 and using Equations (8) to (16). Figure 1 is a smallsignal equivalent circuit of SiGe HBT device. The part (a) of it Fig. 5 Simulated SiGe HBT Device with 0.1 µm Base width JECE Vol. 2 No. 2, 2012 PP. 27-34 ○2011-2012 World Academic Publishing C 30
- 5. Journal of Electrical and Control Engineering JECE (1) Collector-Base junction Capacitance (CBC) (2) Base Resistance (RB) The collector–base capacitance is a junction capacitance. From Equation (7) it is clear that the base resistance shouldFrom Equation (6) and Equation (7) it is clear that the value of be low for higher fmax. It can be calculated by Z-parameters asparasitic capacitance should be low for HF response. The in Equation (14). 】collector-base junction capacitance can be calculated byimaginary part of Y12 as in Equation (9). The plot of CBC at ispresented in Figure 6. The effect of germanium on thecapacitance CBC can be visualized in Figure 7. Fig. 8 Effect of Ge concentration on base resistance RB The Z-parameters are calculated from device simulator ATLAS. Figure 8 represents the effect of Ge concentration on base resistance. It is found that RB decreases as the concentration of Ge increases. 30.12 Ω RB has been obtained at 0.28 Ge concentration. C. Determination of S- Parameters Plots Figure 9 to Figure 12 show the simulated S-parameters plots for this device. Because of the intuitive relationship between coefficients S11 and S22 are conveniently on a smith chart, while S21 and S12 are representing the gain response and that’s why they are typically displayed on a polar plot. The S11 for a bipolar transistor always moves clockwise as Fig. 6 Base-collector junction capacitance CBC frequency increases on the smith chart. The Figures 9 to 12 are simulated S11, S12, S21, and S22. From this Figure it can be interpreted that on increasing theGe concentrations the corresponding collector–base D. Determination of Maximum Oscillation Frequency (fmax)capacitance decreases which in turn increases the maximum and Cut-Off Frequency (fT) for Proposed Deviceoscillation frequency fmax [22]. The value of CBC is 2.76 ×10-15 .F at 0.28 Ge concentration. The maximum oscillation frequency fmax is calculated by the method of extrapolation. This method requires the calculation of power-gain i.e. MSG. The power gain is calculated with the help of S- and Y-parameters of Si-Ge HBT device that are extracted from ATLAS. In this work MSG is calculated by Equation (1). The frequency vs. MSG plot is shown in Figure 13. As it is described above, the fmax is extracted at the point where MSG becomes 0 dB from MSG (in dB) versus log (frequency) plot. The extrapolated fmax is calculated 438 GHz at 0.28 Ge concentration from Figure 13. it is investigated that the maximum oscillation frequency fmax increases on increasing the Ge contents till 0.28 concentration beyond 28% it decreases due to lattice constant mismatch. At 0.28 Ge concentration a record 398 GHz corresponding fT is calculated. It is also investigated that the fT increases on increasing Ge concentration till 28% value of Ge contents. Figure 14 dipicts the variation of extrapolted fmax w.r.t. collector current. The Table 1 describes the overall summary of HF operation of SiGe HBT. It is found that this Si-Ge HBT device is operated at fmax and fT near half terahertz. This HBT in half Tera-Hertz frequencies encompass definite water Fig. 7 Effect of germanium on collector-base junction capacitance (CBC) absorption rates and imitate off metal. Apart from these areas, JECE Vol. 2 No. 2, 2012 PP. 27-34 ○2011-2012 World Academic Publishing C 31
- 6. Journal of Electrical and Control Engineering JECEthis device can infiltrate fog and fabrics [23]. Chemical will be helped by these THz devices. This HBT in THz Radardetection, medicine, chemical spectroscopy, transportation, and will accommodate in investigating hidden universe and planetnational security in addition with weapon fields will also be as well as space applications [18]. This data can be valuable forenriched with this HBT. The study of dust & gas chemistry, Dot 5 project.stellar and galactic constituents as well as evolution cosmology Fig. 9 Simulated S11 Fig. 11 Simulated S21 Fig. 10 Simulated S12 Fig. 12 Simulated S22 JECE Vol. 2 No. 2, 2012 PP. 27-34 ○2011-2012 World Academic Publishing C 32
- 7. Journal of Electrical and Control Engineering JECE IV. CONCLUSIONS In this paper, a simple and accurate method of electrical parameter calculation and HF parameter extraction is presented for SiGe HBT with uniform impurity doping in the base. This is performed by simulated Z- and Y- parameters of proposed device and small signal equivalent circuit method. With the help of these parameters we calculated the intrinsic as well as extrinsic device parameters with higher precision. We found the fine value of base resistance and base-collector junction capacitance which are 30.12 Ω and 2.76 fF respectively. These two values are very helpful for figuring out the high frequency response of proposed device. The extrapolated unity power- gain frequency is calculated 438 GHz. The corresponding unity current-gain frequency is calculated 398 GHz. In our investigation we found that the device current-gain and collector current increases with increasing concentration of germanium. The β is calculated 912 at 28% Ge. While the base resistance and base-collector junction decreases with increasing values of Ge. The high frequency response of proposed model depicted near half tera hertz unity power-gain as well as unity current-gain frequencies. After 28% Ge concentration, these are not supported by present epitaxial technologies and beyond it the improvement associated with Ge seizes may be due to Fig. 13 Plot of frequency (HZ) vs. MSG (dB) lattice constant mismatch. The proposed device with such frequency may be helpful in the realm of medicine, chemical spectroscopy and other space applications, and dot 5 project. REFERENCES [1] M. J. W. Rodwell, M. Urteaga, T. Mathew, D. Scott, D. Mensa, Q. Lee, J. Guthrie, Y. Betser, S.C. Martin, R. P. Smith, S. Jaganathan, S. Krishnan, S. I. Long, R. Pullela, B. Agarwal, U. Bhattacharya, L. Samoska, and M. Dahlstrom, “Submicron scaling of HBTs,” IEEE Trans. Electron Devices, vol. 48, no. 11, pp. 2606–2624, 2001. [2] J. C. Candy, and G. C. Temes, Oversampling Delta-Sigma Data Converters. Piscataway, NJ, IEEE Press, 1992. [3] R Mueller, “Terahertz radiation: applications and sources”, The Industrial Physicist, pp. 27–29, 2003. [4] P. D. Coleman, and R. C. Becker, “Present state of the millimeter wave generation and technique art”, IEEE Trans. Microw. Theory Tech., vol. 7, no. 1, pp. 42–61, 1959. [5] P. D. Coleman, “State of the art: Background and recent developments in millimeter and submillimeter waves”, IEEE Trans. Microw. Theory Tech., vol. MTT-11, no. 5, pp. 271–288. 1963. [6] J. C. Wiltse, “History of millimeter and submillimeter waves”, IEEE Trans. Microw. Theory Tech., vol. MTT-32, no. 9, pp. 1118–1127, 1984. [7] M. Mittleman, M. Gupta, R. Neelamani, R. G. Baraniuk, J. V.Rudd and M. Koch, “Recent advances in terahertz imaging”, Appl. Phys. B, Photophys. Laser Chem., vol. 68, no. 6, pp. 1085–1094, 1999. Fig. 14 Plot of collector current (IC) vs. extrapolated fmax (GHz) [8] P. H. Siegel, “Terahertz technology”, IEEE Trans. Microw. Theory Tech., vol. 50, no. 3, pp. 910–928, 2002. TABLE 1 [9] J.S. Rieh, D. Greenberg, A. Stricker, and G. Freeman, “Scaling of SiGe SUMMARY OF SiGe HBT OPERATION heterojunction bipolar transistors”, in Proc. IEEE, 2005, vol. 93, no. 9, pp. Values for SiGe HBT with 1522–1538. Parameter uniform impurity doping in the [10] S. Weinreb, J. C. Bardin and H. Mani, “Design of cryogenic SiGe low base noise amplifiers”, IEEE Trans. Microw. Theory Tech., vol. 55, no. 11, pp. 2306–2312, 2007. fmax (Hz) 4.38 × 1011 [11] Jiahui Yuan, John D. Cressler, Ramkumar Krithivasan, Thrivikraman, Khater Tushar, H. Marwan, David C. Ahlgren, Alvin J. Joseph and Jae- fT (Hz) 3.98 × 1011 Sung Rieh, “On the Performance Limits of Cryogenically Operated SiGe HBTs and Its Relation to Scaling for Terahertz Speeds”, IEEE RB (Ohm) 30.12 Transactions on Electron Devices, VOL. 56, No. 5, 2009. [12] Fu Jun, “Small-signal model parameter extraction for microwave SiGe CBC (F) 2.76 × 10-15 HBTs based on Y- and Z-parameter characterization”, Journal of Semiconductors, Vol. 30, No. 8, 2009. CCE (F) 1.96 × 10-15 [13] J Gao, X Li and H Wang, “An approach to determine small signal model parameters for InP-based heterojunction bipolar transistors”, IEEE Trans β 912 Semicond Manuf, 19(1): 138, 2006. JECE Vol. 2 No. 2, 2012 PP. 27-34 ○2011-2012 World Academic Publishing C 33
- 8. Journal of Electrical and Control Engineering JECE[14] L Degachi and F M Ghannouchi, “Systematic and rigorous extraction R. K. Chauhan was born in Dehradoon, India in method of HBT small-signal model parameters”, IEEE Trans Microw 1967. He received the B.Tech. degree in Theory Tech, 54(2): 682, 2006. Electronics & Communication Engineering, from[15] K Lee, K Choi and S H Kook, “Direct parameter extraction of SiGe G.B.P.U.A.T - Pantnagar, in 1989 and M.E. in HBTs for the VBIC bipolar compact model”, IEEE Trans Electron Control & Instrumentation, from MNNIT- Devices, 52(3): 375, 2005. Allahabad in 1993 and Ph.D in Electronics[16] T R Yang, J M L Tsai and C L Ho, “SiGe HBT’s small-signal pi Engineering, from IT-BHU, Varanasi, INDIA in modeling”, IEEE Trans Microw Theory Tech, 55(7): 1417, 2007. 2002. He joined the department of ECE, Madan Mohan Malviya Engineering College, Gorakhpur,[17] Umut Basaran, and Manfred Berroth, “High frequency noise modeling of India as a lecturer, in 1993, as an Assistant SiGe HBTs using a direct-parameter extraction method”, in Proceedings Professor since 2002 and thereafter as an of IEEE, 2002. Associate Professor since Jan, 2006 to till date in[18] Pradeep Kumar and R. K. Chauhan, “Device parameter optimization the same institute. He also worked as a Professor in Department of ECE, osilicon germanium HBT for THz applications”, International Journal on Faculty of Technology, Addis Ababa University, Ethiopia between 2003 to Electrical Engineering and Informatics, Vol, 2, No. 4, 2010. 2005. He is reviewer of Microelectronics Journal, CSP etc. His research[19] “Device Simulation Software”, ATLAS User’s manual, SILVACO interests include device modeling and simulation of MOS, CMOS and HBT International, 2004. based circuits. He was selected as one of top 100 Engineers of 2010 by[20] J. D. Cressler, “SiGe HBT technology: a new contender for Si-based RF International Biographical Centre, Cambridge, England. and microwave circuit applications”, IEEE Trans. Microw Theory Tech., E-mail: rkchauhan27@gmail.com vol. 46, issue 5, pp. 572–589, 1998. Ph: +91-9235500556 Department of ECE, Madan Mohan Malviya Engineering College, Gorakhpur-[21] J.M. Zamanillo, A. Tazon, A. Mediavilla and C. Navarro, “Simple 273010, India. Algorithm Extracts SiGe HBT Parameters”, Microwaves & RF, pp. 48-57, 1999.[22] Ankit Kashyap and R. K. Chauhan. “Effect of the Ge profile design on the performance of an n-p-n SiGe HBT-based analog circuit”, Microelectronics journal, MEJ: 2554, 2008.[23] Frank Chang. “Terahertz CMOS SoC for Imaging/Communication Systems” tech. ppt, UCLA, High-Speed Electronics Laboratory. Pradeep Kumar was born in Allahabad, India in 1985. He received his B.Tech. degree in Electronics & Communication Engineering from KCNIT Banda in 2006 and M. Tech degree in Digital Systems from Madan Mohan Malviya Engineering College, Gorakhpur, India. He initially joined VINCENTIT Hyderabad in 2006 and thereafter worked as a lecturer in Dr. K.N.M.I.E.T. Modinagar, Ghaziabad between 2007 and 2008. He is currently working as Assistant Professor in the Deptt. Of Electronics & Communication Engineering at Ideal Institute of Management and TechnologyGhaziabad India. His research interests include characterization & modeling ofSiGe HBT based circuits, THz & millimeter-wave circuit application andmixed signal processing.E-mail: pradeep.hitesh@gmail.comPh: +91-9540642891Department of ECE, Ideal Institute of Management and Technology Ghaziabad,INDIA. JECE Vol. 2 No. 2, 2012 PP. 27-34 ○2011-2012 World Academic Publishing C 34

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