IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 59, NO. 2, FEBRUARY 2011 479 An Accurate Two-Port De-Embedding Technique for RF/Millimeter-Wave Noise Characterization and Modeling of Deep Submicrometer Transistors Xi Sung Loo, Kiat Seng Yeo, Senior Member, IEEE, Kok Wai J. Chew, Member, IEEE, Lye Hock Kelvin Chan, Shih Ni Ong, Manh Anh Do, Senior Member, IEEE, and Chirn Chye Boon Abstract—An accurate and simple noise de-embedding technique is proposed for high-frequency noise characterization of transistors. It is demonstrated on 0.13- m CMOS devices for up to 80 GHz. The proposed technique adopts a generalized two-port fixture model in conjunction with a set of shielded based structures, which enable simple de-embedding of fixture parasitic for up to the Metal 1 level. Unlike other methods, it is capable of simultaneously accounting for the parasitic effects of probe to pad contact impedances and metal finger parasitic while using only three dummy test structures. Also, it is designed to accommodate nonsymmetry between bond pad parasitic elements at two-port without consuming additional silicon area. This corresponds to a reduction in noise de-embedding error, which increases along the frequency domain (6% of NFmin at 80 GHz). Meanwhile, underestimation of metal finger parasitic by conventional techniques has lead to degradation in noise performance (NFmin) of 0.13- m CMOS transistors by more than 3.5 dB at 80 GHz. Further validation results from extracted gate capacitance and transistor gain performance provide solid support to the proposed de-embedding technique. Index Terms—Layout, MOSFETs, scattering parameters, semiconductor device noise. I. INTRODUCTION APID advancement in wireless technology over the past few decades has pushed transistor devices to operate in the vicinity of 100-GHz frequency. As a consequence, high-frequency noise has emerged as a dominant issue in RF integrated circiut (RFIC) design, which is further worsened by scaling of power supply and increase in complexity of RF circuits. This drives the need for precise transistor noise model, which relies greatly on accurate high-frequency noise characterization of the transistor device. A robust noise de-embedding technique is therefore essential to correctly extract the intrinsic noise parameters of the transistor device by completely removing surrounding parasitic noise effects of the test fixture. However, the dominance of fixture parasitic effects as a result of drastic re- R Manuscript received June 26, 2010; revised September 24, 2010; accepted November 03, 2010. Date of publication January 10, 2011; date of current version February 16, 2011. X. S. Loo, K. W. J. Chew, and S. N. Ong are with VIRTUS, Integrated Circuit (IC) Design Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798, and also with GLOBALFOUNDRIES Singapore Pte Ltd., Singapore 738406. K. S. Yeo, L. H. K. Chan, M. A. Do, and C. C. Boon are with VIRTUS, Integrated Circuit (IC) Design Centre of Excellence, School of Electrical and Electronic Engineering, Nanyang Technological University, Singapore 639798. Digital Object Identifier 10.1109/TMTT.2010.2097770 duction in NFmin of CMOS device along the scaling trend [1], [2] has imposed great challenges to noise de-embedding. Several publications on noise de-embedding techniques, which are based on the series-parallel equivalent-circuit model [3]–[5] and generalized network model of test fixture [6]–[10], have been reported. The latter type of technique is well known for its high generality and ability to account for the transmission line effects of interconnects at high frequency. However, the forward coupling mechanisms that exist on the lossy substrate of the test fixture is not addressed in cascade two-port-based techniques [6]–[8]. Meanwhile, high generality of a four-port-based noise de-embedding technique [9], [10] is compromised by ideality assumptions made on the intrinsic standards of test structures. This results in accuracy degradation of the de-embedding method at high frequency. On the other hand, the complexity level of equivalent-circuit-model-based techniques increases from [3]–[5] as accuracy at higher frequency of characterization becomes critical. The more recent technique [5] is superior to other methods, as it is able to remove parasitic effects of the test fixture for up to metal fingers (Fig. 3). Therefore, it is increasingly important for transistor characterization as the de-embedding reference plane is shifted closer to the desired boundary of device. However, it ignores the parasitic effects of probe to pad contact impedance and could only de-embed for up to the Metal 2 level of the test fixture. It is also associated with expensive implementation cost and high de-embedding complexity, as it requires the same number of test structures as [9] for the same purpose. In this paper, a simple and accurate noise de-embedding methodology is presented for noise characterization and modeling of two-port transistor devices. It provides more accurate prediction of the bond pad parasitic than other methods and could de-embed test fixture parasitic for up to the Metal 1 level while consuming 40% less silicon area than [5]. In the proposed de-embedding technique, the test fixture parasitic is modeled by generalized two-port networks to achieve high de-embedding accuracy and alleviate the complexity of de-embedding due to parasitic extraction. In particular, the proposed noise de-embedding technique would be demonstrated on CMOS devices. Such a noise de-embedding technique would be explained in length in Section II. In Section III, the noise de-embedding result is compared with other methods. II. NOISE DE-EMBEDDING METHODOLOGY In the proposed noise de-embedding technique, two port netand are used, respectively, to model works (Fig. 1), 0018-9480/$26.00 © 2011 IEEE 480 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 59, NO. 2, FEBRUARY 2011 M ;M M Fig. 1. Test fixture model of transistor test structure (DUT), which encom), parallel coupling network passes cascade parasitic networks ( ), and series parasitic network ( ). Note that DUT is the acronym for ( “device-under-test.” M Fig. 4. Types of dummy test structures that are adopted in proposed noise de-embedding techniques: OPEN, SHORT, PAD SHORT-OPEN, and PAD OPEN-SHORT. Fig. 2. Schematic layout of ground shielded based transistor test structure (DUT) in ground–signal–ground (G–S–G) configuration. Fig. 5. Network/circuit models of dummy test structures that used for extraction of fixture parasitic. The circuit model of the PAD SHORT-OPEN structure is identical to [4], with the exception that the bond pad parasitic components are not assumed to be the same, which results in higher generality and accuracy. Fig. 3. De-embedding techniques that are proposed in [3], [4], and [6]–[10] are designed to remove test fixture parasitics up to interconnect boundaries (Å ) only. The proposed technique, which is based on mix series-parallel configurations of the parasitic, is able to establish de-embedding reference plane at the Metal 1 level of metal fingers (B). both series and parallel parasitic of interconnects plus metal finand are not necessary to be reciprocal and gers. Both are valid regardless of circuit configuration of parasitic components. The complicated steps in extraction of fixture parasitic components are avoided as only two-port network parameters and are needed to be known. Both cascading netof and , represent the bond pad parasitics that works, appear at Port 1 and Port 2, respectively. Instead of modeling it with a single admittance element [6]–[8], it is described by two , major components, probe to pad contact impedance . The proposed noise and pad to ground impedance de-embedding technique differs from [4] in that the bond pad and are not necessary to be parasitic elements of identical. As a result, it could be applied to more general circumstances. A. Test Structure Fig. 2 illustrates the schematic layout of the ground shielded based [12] transistor test structure that is used for characterization purposes. It consists of eight metal layers and is fabricated on GLOBALFOUNDRIES’ 0.13- m CMOS technology. The intrinsic nMOS device lies in the fixture gap of the Metal 1 ground shield and is surrounded by P guard rings. The wide Metal 1 ground shield is set as the ground reference plane and has a negligible resistance value [12]. The enlarged view of an nMOS device is shown in Fig. 3. LOO et al.: ACCURATE TWO-PORT DE-EMBEDDING TECHNIQUE 481 Fig. 6. Comparisons between measured (DUT) and de-embedded power gain (jS j) of transistor devices [(a) Width = 1 2 5 m, Length = 0:13 m and (b) and (c) Width = 4 2 16 m, Length = 0:25 m]at various dc-biasing conditions [(a) and (b) V = V = 1:2 V and (c) V = 1 V, V = 0:4 V] for frequency range from 4 to 80 GHz. In order to minimize the parasitic effects of narrow interconnects, broad signal pads are designed to allow probes moving closer to the intrinsic nMOS device. Meanwhile, the width of the signal pad is optimized to minimize the coupling between pads. Edges on the interconnects and bond pads are chamfered to minimize parasitic effects that are induced by step discontinuities [13]. Four types of dummy test structures (Fig. 4) are required for characterization of fixture parasitic, namely, OPEN, SHORT, PAD SHORT-OPEN, and PAD OPEN-SHORT. However, only three dummy test structures are required for fabrication as PAD OPEN-SHORT could be realized by simply rotating PAD SHORT-OPEN 180 during on-wafer measurement. This directly saves the cost of implementation while fulfilling the requirement of proposed noise de-embedding technique. The OPEN test structure is simply a fixture frame (without device) that encompasses lead fingers at both the Metal 1 and Metal 2 level. The SHORT test structure is a similar version of OPEN test structure with no fixture gap. The lead fingers are directly connected to a highly conductive Metal1 ground shield through Via1 without introducing additional connection parasitic, as compared to [5]. Also, the forward coupling effects on the proposed SHORT structure can be neglected as there is no fixture gap. With these layout configurations, the parasitic effects of lead fingers can be effectively de-embedded up to the Metal 1 level. Both the OPEN and SHORT structures that are presented in [3] and [4] differs from the proposed technique that the metal fingers are not included. On the other hand, both PAD SHORT-OPEN and PAD OPEN-SHORT structure consist of only bond pads, which are shorted by wide interconnects at only one port than the other. B. Characterization of Fixture Parasitic The equivalent two-port network/circuit models of test structures are shown in Fig. 5. The model of the OPEN structure is similar to the DUT test fixture model, but without the intrinsic two-port device due to its layout configuration. On the other hand, the parasitic effects of the Mp in SHORT structure is ignored as there is negligible forward coupling effect, whereas the couplings to ground at device boundaries are shunted by SHORT interconnections. Bond pad parasitic elements that appear at Port 1 and Port 2 of test fixture are extracted from one-port -parameter measurements on both the PAD SHORT-OPEN structure and PAD OPEN-SHORT structure. The procedure for extraction of the fixture parasitic is summarized as follows. Step 1) Extract parasitic components of bond pad from measured one-port -parameters of PAD SHORT-OPEN structure and PAD OPEN-SHORT structure (1) (2) where is the system characteristic impedance. Step 2) Determine two-port network parameters of series from measured parasitic network parameters of SHORT structure . The obtained , is converted into the -matrix result, (3) where equivalent and -matrices are converted from their (4) Step 3) Extract two-port network parameters of parallel parfrom measured paramasitic network eters of the OPEN structure (5) (6) 482 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 59, NO. 2, FEBRUARY 2011 =125 Fig. 7. Comparisons between measured (DUT) and de-embedded noise parameters (NFmin, Rn, and Topt) of transistor devices [(a) and (b) Width m, : m and (c) Width m, Length : m] at various dc-biasing conditions [(a)–(d) V V : V) for frequency range from Length 4 to 26 GHz. Note that the de-embedded noise parameters by proposed technique and other compared techniques [3]–[5] are almost identical in (c) and (d). = 0 13 = 4 2 16 = 0 25 = DS = 1 2 C. Procedure for -Parameter De-Embedding D. Procedure for Noise De-Embedding The procedure for -parameter de-embedding is as follows: Step 1) De-embed parasitic effects of and from parameters of transistor raw measured . Convert the de-embedded result structure to the -matrix (7) Step 2) De-embed parasitic effects of (8) and convert the Step 3) De-embed parasitic effects of to the matrix, de-embedded result, (9) The procedure for noise de-embedding is as follows. , Step 1) Convert measured noise parameters ( , and ) to the noise correlation matrix (in chain representation) by method , , , and [14]. Calculate from , , , and by applying method [15]. , to , and Step 2) Convert de-embed parasitic noise effects of cascade components where , , and superscript denotes the LOO et al.: ACCURATE TWO-PORT DE-EMBEDDING TECHNIQUE 483 Fig. 7. (Continued.) Comparisons between measured (DUT) and de-embedded noise parameters (NFmin, Rn, and Topt) of transistor devices [(e) and (f) Width = 4 2 16 m, Length = 0:25 m] at various dc-biasing conditions [(e) and (f) V = 1 V, V = 0:4 V] for frequency range from 4 to 26 GHz. Note that the de-embedded noise parameters by proposed technique and other compared techniques [3]–[5] are almost identical in (e) and (f). Hermitian complex conjugate transpose (10) Step 3) De-embed parasitic noise effects of series network. to Convert where A. Impact of Fixture Parasitic on Transistor Power Gain (11) Step 4) De-embed parasitic noise effects of the parallel netto work. Convert where (12) to and calculate the Step 5) Lastly, convert noise parameters of the intrinsic transistor device , and ) by applying the ( method [14] where at millimeter-wave frequencies ( 30 GHz) is performed by an Agilent E8361A PNA (with a frequency extension module) through -parameter measurements. Additional OPEN and SHORT structures of [3] and [4] (without metal fingers) are fabricated for verification purposes. All test structures of [3]–[5] are based on the same shielded pad frame as the proposed structures for fair comparison of de-embedding techniques. (13) III. DE-EMBEDDING VERIFICATION AND RESULTS Noise measurements of 0.13- m nMOS devices are performed by the ATN NP5B measurement system in conjunction with HP8510C VNA for a frequency range from 4 to 26 GHz. Measurements at frequency below 4 GHz are avoided as the measured NFmin of the transistor approaches an uncertainty limit of instrument [1], [2]. Meanwhile, device characterization In this section, the performance of de-embedding techniques at millimeter-wave frequencies is investigated on transistor . Fig. 6(a) shows the measured and de-empower gain m, bedded power gain of the nMOS device (Width m) by various techniques at a dc bias of Length and V. The difference between performance of the proposed technique with and without considering parasitic effects of probe to pad contact resistance is small (0.5 dB at 80 GHz) for frequencies below 80 GHz. This implies that the large discrepancy between performance of the proposed technique and [3] and [4] at high frequencies is mainly due to parasitic effects of metal fingers (3 dB at 80 GHz). On the other hand, de-embedding performance of the proposed technique is identical to [5] when the probe to pad con. In contrast, a tact resistance is neglected slight improvement of transistor power gain over frequency is observed (0.5 dB at 80 GHz) when the effect of probe to pad contact resistance is taken into account by the proposed technique. This clearly demonstrates that the proposed technique is more accurate than [5] at millimeter-wave frequencies. In order to substantiate the verification results discussed above, the de-embedded power gain of large width nMOS devices at different dc-bias modes is also demonstrated. Fig. 6(b) and (c) shows the measured and de-embedded m, power gain of an nMOS device (Width m) by various techniques at both triode Length 484 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 59, NO. 2, FEBRUARY 2011 2 2 2 Fig. 8. Results from reciprocity tests (S = S ) confirm that both transistor devices [(a) Width = 1 5 m, Length = 0:13 m and (b) Width = 4 16 m, Length = 0:25 m] are passive at V = V DS = 0 V. Comparisons between measured and de-embedded NFmin of transistor devices [(c) Width = 1 5 m, Length = 0:13 m and (d) Width = 4 16 m, Length = 0:25 m] for frequency range from 4 to 80 GHz at cutoff mode. 2 ( V, V) and saturation regions ( and V). The comparison results of de-embedding techniques are consistent with those observed in Fig. 6(a) for the device with a smaller width. However, the impact of de-embedding is smaller for larger gain device due to dominance of intrinsic transistor performance over the surrounding test fixture parasitic. For example, the transistor power gain performance shows improvement of only 3.2 dB at 80 GHz after de-embedding by the proposed technique as compared to 11 dB for the device with a smaller width at the same dc-biasing and V). Both de-embedded power condition ( gain performance by the proposed technique and [5] are almost identical ( 0.2-dB difference at 80 GHz) as the impact of contact resistance becomes smaller for the transistor device with a large size. Nevertheless, the results presented in Fig. 6(a)–(f) confirms that the proposed de-embedding technique remains valid regardless of transistor geometries. B. Comparison of Noise De-Embedding Results The impact of de-embedding techniques on noise performance of the nMOS device with different geometry is also investigated. Fig. 7(a) and (b) shows the measured and de-embedded noise parameters of transistor device m, Length m) for a frequency (Width and range from 4 to 26 GHz at the saturation mode ( V). As evidenced from the results presented in the previous section, clear separation between the predicted NFmin by the proposed technique and [3] and [4] beyond 15 GHz is mainly contributed by parasitic effects of metal fingers. On the other hand, de-embedded noise parameters by the proposed technique are in good agreement with [5] for even a lesser number of dummy test structures used. However, the distinction between de-embedded noise performance of the large size transistor by the proposed technique and [3] and [4] remains negligible for frequencies below 26 GHz at both saturation [see Fig. 7(c) and (d)] and triode regions [see Fig. 7(e) and (f)]. Further, de-embedding by both the proposed technique and compared techniques only resulted in a slight improvement of the transistor NFmin by less than 1 dB at 26 GHz. These results support the claim by [17] that nMOS devices with smaller width or size are more vulnerable to de-embedding errors as the transistor test structure (DUT) is increasingly dominated by fixture components. Direct noise measurement at millimeter-wave frequencies is impossible due to the limitation of the existing noise measurement system. Instead, the noise parameters of a transistor can LOO et al.: ACCURATE TWO-PORT DE-EMBEDDING TECHNIQUE 485 = DS = 0 Fig. 9. (a) Comparisons between extracted gate capacitance of 0.13-m nMOS devices by different de-embedding techniques at V V V. Com[magnitude (b) and phase (c)] for frequency range from 4 to 80 GHz. parisons between bond pad parasitic elements at two-port Z ; Z ) and Y ; Y (d) Residual error (expressed in percentage of device NFmin) in de-embedded NFmin of the nMOS device as a result of failure to account for the discrepancy between bond pad parasitic elements at two ports. NF50 of input and output bond pad parasitic networks M ; M are also shown for same frequency range from 4 to 80 GHz. ( ( ) ( be calculated directly from its two-port network parameters [15] once it operates as a passive device. The equality between and (both magnitude and phase) in Fig. 8(a) and (b) confirms that both of the transistor devices mentioned above are reand V). ciprocal and passive at the cutoff mode ( Fig. 8(c) and (d) illustrates the comparisons between the extracted and de-embedded NFmin of the nMOS devices by various techniques for frequency from 4 to 80 GHz at zero gate and drain bias. Both results presented in Fig. 8(c) and (d) show that the difference between the de-embedded NFmin by the proposed technique and [3] and [4] increases consistently along the frequency axis as the impact of metal finger parasitic becomes significant at millimeter-wave frequencies. It exhibits the largest m, impact on the transistor with smaller size (Width m), as clearly shown by the 4-dB margin in Length between the de-embedded NFmin by the proposed technique and [3] and [4] at 80 GHz. Similar to the results presented in Fig. 6(a)–(f), noise de-embedding performance of both the proposed technique and [5] are highly correlated with each other for the same OPEN and SHORT structures used. The performance of the five-step de-embedding technique would be worse than ) predicted if it is based on the original proposed structures in [5] (nonshielded based), which can de-embed t he fixture parasitic for up to the Metal 2 level only. C. Validation of Metal Finger Parasitic Effects In order to verify the accuracy of the de-embedding techV gate caniques, the total zero bias is extracted at pacitance of the 0.13- m nMOS device a sufficiently low frequency (2 GHz) such that it could be ap[18]. Note that the intrinsic comproximated by ponents of the nMOS device are negligible since it is turned off [18]. The extracted gate capacitance after de-embedding is then compared with the reference value that is calculated based on process parameters of the 0.13- m CMOS technology. The results in Fig. 9(a) clearly show that the extracted gate capacitance using the proposed technique and [5] are closely matched with the reference value. It varies proportionally with the device of Device #1 of Device size as indicated ( #2). This confirms that the proposed technique could correctly de-embed the test fixture parasitic up to the metal fingers. Meanwhile, extracted gate capacitance of Device #1 by [3] and [4] is 486 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 59, NO. 2, FEBRUARY 2011 about five times higher than actual value as the parasitic capacitance between metal fingers is included in the result. D. Variability of Bond Pad Parasitic Elements Variability between bond pad parasitic elements of and is also investigated and its impact on the noise de-embedding result is discussed. In order to produce stable and consistent results, the skating distances of probes are maintained around 50 to 60 m [16]. Fig. 9(b) and (c) shows the extracted bond pad parasitic components of the test fixture, which include and pad to ground probe to pad contact impedances ). Note that the impedance value of admittances has a magnitude of approximately 40% higher than on average for frequency range from 4 to 80 GHz. This is mainly due to the discrepancy in surface profiles of probes, which resulted in a different contact area between the probe and bond pad [11]. In contrast, the difference between pad to ground admittances is negligible even at 80 GHz. Variations between bond parasitic elements at the input and output ports resulted in increasing separation between NF50 of bond pad parasitic and along the frequency domain [see networks, Fig. 9(d)]. Failure to account for such variation by [4] would induce 3.9% to 6% error (at 80 GHz) in the de-embedded NFmin of the transistor devices highlighted in Fig. 9(d). In other words, more accurate prediction of the bond pad parasitic by the proposed technique has led to better noise de-embedding performance than other reported work [3]–[8]. IV. CONCLUSION In this paper, an accurate and simple noise de-embedding methodology has been proposed for high-frequency noise characterization of transistor devices. It is developed based on a generalized two-port fixture model in conjunction with a set of shielded-based test structures, which enable accurate de-embedding of the test fixture parasitic for up to metal fingers. The proposed noise de-embedding technique has been validated on 0.13- m technology based CMOS transistors for up to 80 GHz. It shows superior performance to techniques [3] and [4] at high frequencies as the parasitic effects of metal fingers dominate. Compared to technique [5], which has similar de-embedding capability (for up to metal fingers), the proposed technique consumes less silicon area, is simpler, and has been proven to be more accurate in high-frequency characterization of the active CMOS device. Further, better prediction of the bond pad parasitic gives additional boost to the noise de-embedding performance of the proposed technique as compared to other reported work [3]–[8]. These advantages confirmed that the proposed de-embedding technique is suitable for noise characterization of CMOS devices at millimeter-wave frequencies. Moreover, the proposed technique can also be applied to other types of active devices, which include III–V compound transistors. ACKNOWLEDGMENT The authors are grateful to GLOBALFOUNDRIES Singapore Pte Ltd., Singapore, for fabricating the test structures. REFERENCES [1] “The International Roadmap for Semiconductors (ITRS),” 2007. [Online]. Available: www.itrs.net/reports.html [2] C.-H. Chen, Y.-L. Wang, M. H. Bakr, and Z. Zeng, “Novel noise parameter determination for on-wafer microwave noise measurements,” IEEE Trans. Instrum. Meas., vol. 57, no. 11, pp. 2462–2471, Nov. 2008. [3] M. C. A. M. Koolen, J. A. M. Geelen, and M. P. J. G. Versleijen, “An improved de-embedding technique for on-wafer high-frequency characterization,” in Proc. Bipolar Circuits Technol. Meeting, Sep. 9–10, 1991, pp. 188–191. [4] T. E. Kolding and C. R. Iversen, “Simple noise de-embedding technique for on-wafer shielded based test fixtures,” IEEE Trans. Microw. Theory Tech., vol. 51, no. 1, pp. 11–15, Jan. 2003. [5] I. M. Kang, S.-J. Jung, T.-H. Choi, J.-H. Jung, C. Chung, H.-S. Kim, H. Oh, H. W. Lee, G. Jo, Y.-K. Kim, H.-G. 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Theory Tech., vol. MTT-25, no. 10, pp. 819–822, Oct. 1977. [14] H. Hillbrand and P. Russer, “An efficient method for computer aided noise analysis of linear amplifier networks,” IEEE Trans. Circuits Syst., vol. CAS-23, no. 4, pp. 235–238, Apr. 1976. [15] R. Q. Twiss, “Nyquist’s and Thevenin’s theorems generalized for nonreciprocal linear networks,” J. Appl. Phys., vol. 26, no. 5, pp. 599–602, May 1955. [16] T. E. Kolding, “General accuracy considerations of microwave on-wafer silicon device measurements,” in IEEE MTT-S Int. Microw. Symp. Dig., 2000, vol. 3, pp. 1839–1842. [17] C. K. Liang and B. Razavi, “Systematic transistor and inductor modeling for millimeter-wave design,” IEEE J. Solid-State Circuits, vol. 44, no. 2, pp. 450–457, Feb. 2009. [18] M. Je, J. Han, H. Shin, and K. Lee, “A simple four-terminal small signal model of RF MOSFETs and its parameter extraction,” Microelectron. Rel., vol. 43, no. 4, pp. 601–609, 2003. Xi Sung Loo was born in Kuala Lumpur, Malaysia, in 1982. He received the B.E. (Hons.) degree in electrical and electronic engineering from Nanyang Technological University, Singapore, in 2007, and is currently working toward the Ph.D. degree at Nanyang Technological University. His research interests mainly focus on design, layout optimization, and high-frequency noise characterization of RF CMOS devices for modeling purposes. LOO et al.: ACCURATE TWO-PORT DE-EMBEDDING TECHNIQUE Kiat Seng Yeo (SM’09) received the B.E. (Hons.) degree in electronics and Ph.D. degree in electrical engineering from Nanyang Technological University, Singapore, in 1993 and 1996, respectively. In 1996, he joined the School of Electrical and Electronic Engineering, Nanyang Technological University, as a Lecturer, and became an Associate Professor and Professor in 2002 and 2009, respectively. He became Sub-Dean (Student Affairs) in 2001, Head of the Department of Circuits and Systems in 2005, and Interim Director, VIRTUS, Integrated Circuit (IC) Design Centre of Excellence in 2009. He provides consultancy services to statutory boards and multinational corporations in the areas of semiconductor devices and electronic circuit design. He has been extensively involved in the modeling and fabrication of small MOS/bipolar integrated technologies for the last 17 years. His current research interests include the design of new circuits and systems (based on scaled technologies) for low-voltage low-power applications, RFIC design, integrated circuit design of BiCMOS/CMOS multiple-valued logic circuits, domino logic and memories, and device characterization of deep-submicrometer MOSFETs. Kok Wai J. Chew (M’02) received the B.E. (Hons.) degree in electrical engineering and M.Eng. and Ph.D. degrees in electrical engineering from Nanyang Technological University, Singapore, in 1996, 1999, and 2007, respectively. In 1998, he joined Chartered Semiconductor Manufacturing, Singapore, as an Engineer with the Mixed-Signal/RF CMOS Technology Development Group, where he was involved in mixed-signal process characterization and integration, RF CMOS device layout, and characterization. In 2002, he became a Senior Engineer and joined the SPICE Modeling Group, where he is currently responsible for RF CMOS and SiGe BiCMOS actives and passives test-chip design, characterization, modeling, and customer support across all technologies. He is a Member of Technical Staff and Group Leader for RF CMOS characterization and modeling. He has authored or coauthored over 15 papers in leading technical journals and conferences worldwide. He holds 18 U.S. patents. His research interests include characterization and modeling of RF MOS/bipolar transistors, RF passives, and noise characterization and modeling of MOS transistors. Lye Hock Kelvin Chan was born in Penang, Malaysia, in 1983. He received the B.E. (Hons.) degree in electrical and electronic engineering from Nanyang Technological University, Singapore, in 2007, and is currently working toward the Ph.D. degree at Nanyang Technological University. His research interests mainly focus on design and high-frequency noise modeling of RF CMOS device for low-power applications. 487 Shih Ni Ong was born in Johor, Malaysia, in 1983. She received the B.E. (Hons.) degree in electrical and electronic engineering from Nanyang Technological University, Singapore, in 2007, and is currently working toward the Ph.D. degree at Nanyang Technological University. Her research interests mainly focus on high-frequency noise characterization and modeling of RF CMOS device for IC design purposes. Manh Anh Do (SM’05) received the B.Sc degree in physics from the University of Saigon, Saigon, Vietnam, in 1969, and the B.E. (Hons.) degree in electronics and Ph.D. degree in electrical enigneering from the University of Canterbury, Canterbury, New Zealand, in 1973 and 1977, respectively. From 1977 to 1989, he held various positions including: Design Engineer, Production Manager, and Research Scientist in New Zealand, and Senior Lecturer with National University of Singapore. In 1989, he joined the School of Electrical and Electronic Engineering, Nanyang Technological University (NTU), Singapore, initially as a Senior Lecturer, then an Associate Professor in 1996, and then Professor in 2001. He has been a consultant for many projects in the electronic industry, and was a key consultant for the implementation of the $200 million Electronic Road Pricing (ERP) Project in Singapore from 1990 to 2001. From 1995 to 2005, he was Head of the Division of Circuits and Systems, NTU. He is currently the Director of the Centre for Integrated Circuits and Systems, NTU. He has authored or coauthored over 100 papers in leading journals and 135 papers international conferences in the areas of electronic circuits and systems. His current research is focused on mobile communications, RF IC design, mixed-signal circuits and intelligent transport systems. Prior to that, he specialized in sonar designing and biomedical signal processing. Dr. Do is a Fellow of the Institution of Engineering and Technology (IET), U.K. He is a Chartered Engineer. He was a council member of the IET (from 2001 to 2004). He was an associate editor for the IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES (2005, 2006). Chirn Chye Boon received the B.E. degree (Hons.) in electronics and Ph.D. degree in electrical engineering from Nanyang Technological University (NTU), Singapore, in 2000 and 2004, respectively. In 2005, he joined NTU, as a Research Fellow and became an Assistant Professor that same year. Prior to that, he was with Advanced RFIC, where he was a Senior Engineer. He specializes in direct conversion RF transceiver front-end design, phase-locked-loop frequency synthesizers, clock and data recovery circuits, and frequency dividers. Dr. Boon is a reviewer for the IEEE TRANSACTIONS OF CIRCUITS AND SYSTEMS—PART I: REGULAR PAPERS, the IEEE MICROWAVE AND WIRELESS COMPONENTS LETTERS, and the IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES.