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1 3028 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 56, NO. 12, DECEMBER 2008 Low Insertion-Loss Single-Pole Double-Throw Reduced-Size Quarter-Wavelength HEMT Bandpass Filter Integrated Switches Jeffrey Lee, Student Member, IEEE, Ruei-Bin Lai, Student Member, IEEE, Chung-Chun Chen, Student Member, IEEE, Chin-Shen Lin, Student Member, IEEE, Kun-You Lin, Member, IEEE, Chau-Ching Chiong, and Huei Wang, Fellow, IEEE Abstract This paper proposes a circuit topology which reduces the chip size of single-pole double-throw (SPDT) quarter-wavelength bandpass filter-integrated switches (FIS). A 40-GHz mhemt MMIC SPDT switch has been implemented and demonstrates a measured insertion loss lower than 1 db and an isolation better than 30 db. Another 50-GHz phemt MMIC SPDT achieves 1.5 db insertion loss and 22 db isolation. The low insertion loss and high isolation shows that the circuit performance is improved along with the reduction of the size. The systematic design approach of the reduced-size FIS is described, together with the analysis of the insertion loss and isolation. Index Terms Filters, reduced-size, single-pole double-throw (SPDT), switches. I. INTRODUCTION T HE RF switch is important in time division duplex wireless communication systems. Since a filter is required in front of a switch when integrating a wireless system, the integration of filter function and a switch function achieves the benefit of low cost, and the reduction of the losses. The concept to integrate the filter function into a switch was proposed to reduce the circuit area and the loss of the interconnections [1] [3]. In [1], the concept of filter-integrated single-pole-single-throw (SPST) switch (FIS) gives the systematic design approach to implement the switch using the filter synthesis of a 1-GHz quarter-wavelength bandpass filter. To expand an SPST FIS into a single-pole double-throw (SPDT) FIS, the sharing resonator technique was used to combine two SPST FIS so that the impedance of the off-state SPST switch will not influence the insertion loss of SPST switch at the on state [2], [3]. Due to the impedance transformer, the frequency response of the entire SPDT switch can be synthesized systematically. In [2], a narrow band hybrid SPDT Manuscript received April 10, 2008; revised August 13, First published November 18, 2008; current version published December 05, This work was supported in part by the National Science Council of Taiwan (NSC E ) and Excellent Research Projects of National Taiwan University (97R ). The authors are with the Graduate Institute of Communication Engineering and the Department of Electrical Engineering, National Taiwan University, Taipei 106, Taiwan ( kunyou@ew.ee.ntu.edu.tw; hueiwang@ ew.ee.ntu.edu.tw). Color versions of one or more of the figures in this paper are available online at Digital Object Identifier /TMTT switch using diodes with integration of coupled-resonator filter was demonstrated by the sharing resonator technique. The hybrid switch has a 5% fractional bandwidth (FBW) because of the microwave filter topology. The concept to extend the quarter-wavelength filter-integrated switch from SPST switch in [1] into SPDT switch was presented in [3]. The quarter-wavelength impedance transformers were integrated as a part of the quarter-wavelength bandpass filter; however, because of the long electrical length of a quarter-wavelength transmission line, the size of the quarter-wavelength FIS is large. In order to resolve this, the concept of reduced-size filter-integrated SPDT switch is introduced in [4]. By using the size reduction technique, one 40-GHz MMIC SPDT switch is implemented using GaAs-based mhemt process and demonstrated low insertion loss, good return loss and high isolation [4]. In this paper, the systematic design method of reduced-size SPDT FIS is described in an analytic way, in addition to the MMIC performance presented in [4]. The insertion loss and isolation of reduced-size SPDT FIS are analyzed, along with the evaluation of other circuit parameters. Two millimeter-wave (MMW) MMIC SPDT switches have been successfully demonstrated using this size reduction technique. The 40-GHz SPDT switch using mhemt process [4] has a bandpass filter frequency response and achieves the measured insertion loss, return loss and isolation of better than 1, 12, and 20 db, respectively, from 30 to 50 GHz with a chip size of only 2 mm 1 mm. The 50-GHz SPDT switch using a GaAs-based phemt process also demonstrated insertion loss, return loss and isolation better than 1.5, 10, and 22 db, respectively, from 40 to 60 GHz. The chip size has been reduced to 1.5 mm 1 mm compared with the one reported in [3] using the same process (2 mm 1 mm). To the best of our knowledge, the performance of this 50-GHz SPDT FIS presents the lowest insertion loss among the reported SPDT MMIC switches in this frequency range. II. CONCEPT OF REDUCED-SIZE FIS There are two ways to reduce the size of the quarter-wavelength FIS, described as follows. A. Shortening Series Quarter-Wavelength Transmission Line In [5], a size-reduction method is offered to shorten the series quarter-wavelength transmission line. The quarter-wavelength transmission line of Fig. 1(a) has the equivalent circuit of the /$ IEEE

2 LEE et al.: LOW INSERTION-LOSS SPDT REDUCED-SIZE QUARTER-WAVELENGTH HEMT BANDPASS FILTER INTEGRATED SWITCHES 3029 Fig. 1. (a) Quarter-wavelength transmission line. (b) Equivalent circuit of quarter-wavelength transmission line with reduce-sized technique. shorter transmission line with shunt capacitances on each side of the line as shown Fig. 1(b). It can be proved that (1) (2) where,, and and are characteristic admittances of transmission lines, hence. It can be easily observed that not only the length of the transmission line is shorter but also the width of the transmission line is narrower if the size-reduction method is applied. Moreover, it is noted that the shunt capacitance does not need to appear in the switch schematic during the circuit design most of the time, because the shunt capacitance can be absorbed in equivalent capacitance of the off-state transistor. We will further describe this later. B. Shortening Shunt Quarter-Wavelength Transmission Line Resonator The other way to reduce the size of the quarter-wavelength filter-integrated switch is to shorten the shunt quarter-wavelength transmission line resonator, as shown in Fig. 2. Fig. 2(a) shows the original shunt quarter-wavelength transmission line resonator in the quarter-wavelength BPF design. The transmission line in Fig. 2(a) can be expressed as the equivalent LC-resonator shown in Fig. 2(b), where (3) (4) Fig. 2. Step of how to shorten the shunt quarter-wavelength transmission line resonator. (a) Original shunt quarter-wavelength transmission line resonator. (b) LC-resonator which is equivalent to the shunt quarter-wavelength transmission line resonator (c) separating partial capacitance from the LC-resonator in (b). (d) Transferring the new LC-resonator in (c) into a new shunt quarter-wavelength transmission line resonator. In Fig. 2(c),, ; hence, and therefore,,. Therefore, we can also obtain the same conclusion as that of the first method, which is not only the length of the transmission line is shorter, but the width of the line is narrower. Looking into Fig. 2(d) from another viewpoint, the shunt transmission line can be expressed in terms of characteristic admittance, center frequency and electrical length. From the equivalent circuit shown in Fig. 2(a) and (d), the following equation can be derived at frequency : hence (7) where is the characteristic admittance of the transmission line in Fig. 2(a). The capacitance in Fig. 2(b) can then be separated into, and, as shown in Fig. 2(c), where. The new LC-resonator composed of and in Fig. 2(c) can be transferred back to a new quarter-wavelength transmission line resonator with center frequency at, character admittance, where (5) (6) Because, and from (3) (6) it can be derived that (8) (9) (10) (11)

3 3030 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 56, NO. 12, DECEMBER 2008 Fig. 3. (a) Proposed series quarter-wavelength transmission line with two shunt quarter-wavelength transmission line on the both ends. (b) Equivalent circuit by using size-reduction technique mentioned in Figs. 1 and 2. (c) Replacing the capacitance on the left side of the circuit to off-state transistor. Therefore (12) Step Step Step Step are characteristic admittances of those quarterwavelength transmission lines. 2) The first size-reduction method is applied, and the equivalent circuit is shown in Fig. 4(b). Here and are characteristic admittances, and are electrical lengths of the series transmission lines. 3) The second size-reduction method is also used, as shown in Fig. 4(c), where the capacitances from the first and the second method are combined together. Here and are characteristic admittances, and are electrical lengths of the shunt transmission lines. 4) The capacitance is replaced by the off-state transistor, which is shown in Fig. 4(d). It should be noted that the capacitance shunt with a quarter-wave length transmission line in the right hand side of the circuit is not replaced by the transistor. The shunt capacitance and the quarter-wavelength transmission line over there are used in the shared resonator technique, and the admittances of these are. 5) Looking into the isolation path of another half circuit of the SPDT switch shown in Fig. 4(e), we can choose a shunt transmission line that makes the equal to the in Fig. 4(d). It should be noted that the shunt transmission line is an open stub because that is composed of a capacitance parallel with a quarter-wavelength resonator with the center frequency at. The admittance of these are, as given by The capacitance in Fig. 2(d) can be merged into the in Fig. 1(b) and then into the equivalent capacitance of the off-state transistor. To summarize the two methods mentioned above, a simple circuit shown in Fig. 3 is used as an example to illustrate the size-reduction method step by step. In Fig. 3(a), a schematic which includes a series quarter-wavelength transmission line and two shunt quarter-wavelength transmission lines on the both ends is proposed. Using the size-reduction techniques shown in Figs. 1 and 2, the equivalent circuit of Fig. 3(a) can be drawn as Fig. 3(b). It should be noted that the capacitances on both ends of the series transmission line can be merged into the combination of in Fig. 1(a) and in Fig. 2(d). In other words, is equals to. The final step is to replace the shunt capacitance to off-state transistor, which is shown in Fig. 3(c). III. DESIGN AND ANALYSIS OF REDUCED-SIZE FIS Step (13) It can be observed that the imaginary part of is dominated by the capacitance at the frequency near. Hence the open stub is a better choice in the reduced-size FIS design when the shared-resonator technique is applied. The way to choose and, the characteristic admittance and electrical length of open stub, is to make the imaginary part and the slope of the frequency response of equal to and the slope of the frequency response of. In Fig. 4(e), mean equivalent conductance of the on-state transistors and. 6) Both the through path with the shunt off-state transistors and the isolation path with the shunt on-state transistors are combined together to form the reduced-size SPDT FIS, as shown in Fig. 4(f). A. Design Concept of RFIS Similar to the SPDT FIS design procedure described in [3], the reduced-size SPDT FIS can also be designed systematically. We will enhance the description of the circuit design presented in [4] here. A third-order bandpass filter structure is used for the 40-GHz reduced-size MMIC SPDT FIS. The step-by-step design procedure is stated as follows. Step 1) A third-order quarter-wavelength BPF is designed, as shown in Fig. 4(a). Here,,, and B. Analysis of RFIS Switch The insertion loss and the isolation of a quarter-wavelength SPDT FIS have been analyzed in [3]. Although the circuit topology of the reduced-size FIS is similar to that of a conventional FIS, the electrical lengths of transmission lines are shorter than 90 in Fig. 4(f). Hence, the analysis of the RFIS is more complex than that of a conventional FIS. 1) Insertion Loss: The insertion loss of the reduced-size FIS is investigated first; however, since the sharing resonator tech-

4 LEE et al.: LOW INSERTION-LOSS SPDT REDUCED-SIZE QUARTER-WAVELENGTH HEMT BANDPASS FILTER INTEGRATED SWITCHES 3031 Fig. 4. (a) Original third BPF. (b) Equivalent circuit by using first size-reduction method. (c) Equivalent circuit by using second size-reduction method. (d) Replacing the capacitance to off-state transistors. (e) Using sharing resonator technique. (f) Whole circuit of reduced-sized FIS. nique [2], [3] is applied, the isolation will be considered simultaneously in Fig. 4(e). It can be derived that Similarly, can be derived as (16) (14) hence, shown in Fig. 4(e), can be calculated under the condition of terminating in the other side of the circuit as Because the and have to be the same near, hence (17) From (1), (2) and (17), it can be derived that (15) (18)

5 3032 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 56, NO. 12, DECEMBER 2008 Moreover, the slope of the frequency response of and also have to be the same near, hence With (18) with (19), we have (19) (20) Using (18) and (20), and can be calculated numerically. Now we can go back on the analysis of insertion loss. From (15), (16), and the through path of reduced-size FIS, which is like a filter matched to, the through path of reduced-sized FIS has its equivalent circuit at. The insertion loss can be expressed as Fig. 5. Equivalent circuit of the isolation part of reduce-sized quarter-wavelength bandpass FIS., with reference admittance of both input and isolation paths, of the whole circuit can be calculated as (21) where mean equivalent conductance of the on-state transistors and. From (1) and (21), we have (22) From (15) and (16), we have hence Therefore, (23) (24) (25) (26) It is interesting that this equation is the same as that derived in [3], but the equivalent conductance of the on-state transistors in the reduced-sized FIS is larger than that in a conventional FIS, and therefore the insertion loss can be improved. Also, the insertion loss is improved due to the lower loss of a shorter transmission line. 2) Isolation: Fig. 5 shows the equivalent circuit of the isolation path of reduced-size FIS. The open stub, acting as a sharing resonator and the through path are combined into.however, there is something to be mentioned before the analysis of the isolation. As shown in Fig. 5, the two 2-port networks A and B are cascaded together. Assume the Y parameters are and (27) (28) (29) Substituting (26) (29) into (23) yields (30), shown at the bottom of this page. Also, because (31) (30)

6 LEE et al.: LOW INSERTION-LOSS SPDT REDUCED-SIZE QUARTER-WAVELENGTH HEMT BANDPASS FILTER INTEGRATED SWITCHES 3033 TABLE II DESIGN PARAMETERS OF SIZE-REDUCTION FILTER BY USING BOTH REDUCTION METHODS (34) Fig. 6. Frequency response of ideal filter and size-reduction filter after using both reduction methods. Hence TABLE I DESIGN PARAMETERS OF THIRD-ORDER BANDPASS FILTER (35) Let us investigate the reduced-size FIS, as shown in Fig. 4, with the center frequency, the smallest equivalent capacitance for the off-state transistor. It can be derived that, in Fig. 4(c), we have and (32), shown at the bottom of the page, can be derived. As mentioned in Section II, and are larger in the reduced-size FIS than that of a conventional FIS. As a result, the isolation is also improved by the size-reduction technique. C. Higher Frequency Performance Not only can the insertion loss and isolation be improved, but also it can be shown that a conventional traveling wave switch needs smaller devices than a reduced-size FIS does at the same cutoff frequency. In other words, under the same MMIC technology, the reduced-size FIS can operate at higher frequency if the same size of transistor is used. This is illustrated as follows. Assume the traveling wave switch has the cutoff frequency and the equivalent capacitance for the off-state transistor in this circuit, that is, (33) where Hence (36) (37) (38) (39) where,. Although it is not apparent that is larger than, and are usually higher than in a BPF design. Therefore, can be chosen to be larger than, which means that the traveling wave FIS needs a smaller device than that the reduced-size FIS switch does at the same cutoff frequency. Therefore, a reduced-size FIS can operate at (32)

7 3034 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 56, NO. 12, DECEMBER 2008 Fig. 7. Frequency response of ideal filter and size-reduction filter after replacing capacitances to transistors. TABLE III DESIGN PARAMETERS OF SIZE-REDUCTION FILTER AFTER REPLACING CAPACITANCES TO TRANSISTORS Fig. 8. Imaginary part of Y in Fig. 4(e) and Y in Fig. 4(d). TABLE IV DESIGN PARAMETERS IN FIG. 4(e) a higher frequency than a conventional traveling wave FIS if an identical transistor size is applied in the same MMIC process. IV. DESIGN EXAMPLE OF REDUCED-SIZE FIS There are two MMIC switches using the reduced-size technique demonstrated in this paper. One is a 40-GHz mhemt SPDT FIS, and the other is a 50-GHz phemt SPDT FIS. We will use the 40-GHz switch to illustrate the design methodology. In [4], the 40-GHz MMIC mhemt SPDT FIS switch has been presented, with the design parameters illustrated. We will describe how the design parameters were extracted step by step in this paper, with the correspondence for the design concept of reduced-size FIS mentioned above. The process used in this circuit is WIN Semiconductors 0.15-ìm high linearity AlGaAs/InGaAs/GaAs mhemt MMIC process [7]. In this design, the device sizes are 4-finger with total periphery of and 4-finger with total periphery of. The design targets of this switch are center frequency of 40 GHz, 50% FBW, and 0.01-dB ripple in a third-order bandpass filter frequency response. 1) As shown in Fig. 4(a), a bandpass filter is designed, and its frequency responses and design parameters are shown in Fig. 6 and Table I, respectively. 2) As shown in Fig. 4(b) and (c), the first and second size-reduction methods are applied. The design parameters can be extracted from (1), (2), (5), and (6). The frequency responses in this step and design parameters are shown in Fig. 6 and Table II, respectively. Fig. 9. Final simulation result of reduced-size FIS. 3) As shown in Fig. 4(d), some of the capacitances in Fig. 4(c) are replaced by transistors, and frequency responses and design parameters in this step are shown in Fig. 7 and Table III, respectively. 4) As shown in Fig. 4(e), the imaginary part and the slope of the frequency response of equal to the imaginary part and the slope of the frequency response of in Fig. 4(d). The frequency responses and design parameters in this step are shown in Fig. 8 and Table IV, respectively. 5) The parasitic effect such as junction will need to be taken into considerations by the full-wave EM simulations. The design parameters need to be fine-tuned after the EM simulations. Then the final circuit simulation can be plotted, as shown in Fig. 9, while the design parameters are shown in Table V. The complete circuit schematic diagram is illustrated in Fig. 10. The 50-GHz phemt SPDT FIS can be designed in a similar way.

8 LEE et al.: LOW INSERTION-LOSS SPDT REDUCED-SIZE QUARTER-WAVELENGTH HEMT BANDPASS FILTER INTEGRATED SWITCHES 3035 TABLE V COMPARISON BETWEEN DESIGN PARAMETERS OF THE Q-BAND mhemt REDUCED-SIZE FIS AND ORIGINAL FILTER Fig. 11. Chip photograph of the Q-band mhemt reduce-sized filter-integrated SPDT switch with a chip size of 2 2 1mm. Fig. 12. Simulation and measurement result of the Q-band reduce-sized filterintegrated SPDT switch. Fig. 10. switch. Circuit schematic of the Q-band reduce-sized filter-integrated SPDT TABLE VI DESIGN PARAMETER OF V-BAND PHEMT SPDT SWITCH V. EXPERIMENTAL RESULTS A. 40-GHz mhemt SPDT FIS Fig. 11 illustrates the chip photograph of the 40-GHz mhemt SPDT FIS, with the chip size of 2 mm 1 mm. The discontinuous junctions, parasitic effects of the transmission lines are simulated using SONNET 0 [6]. In order to measure the complete frequency responses of this SPDT FIS, two different test sets for different bands (dc to 50 GHz, -band) are used. Fig. 12 shows the measured and simulated results of the on-state switch. It exhibits an insertion loss, return loss and isolation better than 1, 10, and 32 db, respectively, from 30 to 50 GHz. The measurement results agree well with the simulation results to 50 GHz. The passive mhemt model at the frequency higher than 50 GHz still needs further investigation. Due to limitation of our signal source, input power is only up to 13 dbm at 40 GHz. No output power compression is observed. B. 50-GHz phemt SPDT FIS The process used in this design is WIN Semiconductors m high linearity AlGaAs/InGaAs/GaAs phemt MMIC process [7]. In this design, the HEMT device of 2-finger with total periphery of 100 m and 4-finger with total periphery of 160 m were used. The design targets of this FIS are center frequency of 50 GHz, 40% FBW, and 0.01-dB ripple 3rd-order in a bandpass filter response. With the target frequency response, the systematic synthesis approach in Section III is applied to determine the characteristic impedance and the length of the transmission lines. Fig. 13 shows the complete schematics of the 50-GHz MMIC SPDT FIS, and Table IV shows the design parameter of the complete circuit. The discontinuous junctions, parasitic effects of the transmission lines are all characterized using SONNET electromagnetic simulation tool [6]. Fig. 14 illustrates the chip photograph of the SPDT switch with the chip size of 1.5 mm 1 mm. which is 25% less than the conventional quarter-wavelength SPDT FIS reported in [3]. The chip was also measured via on-wafer test. Fig. 15 illustrates the measured and the simulated results of the on-state switch. It

9 3036 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 56, NO. 12, DECEMBER 2008 TABLE VII PUBLISHED HEMT SWITCHES Fig. 13. switch. Circuit schematic of the 50-GHz reduce-sized filter-integrated SPDT Fig. 15. Simulation and measurement result of the V -band reduce-sized filterintegrated SPDT switch. demonstrates an insertion loss below 2 db from 40 to 65 GHz. Due to limitation of our signal source, input power is only up to 13 dbm at 50 and 60 GHz. No output power compression is observed. Table VII compares the previously reported MMW MMIC SPDT switches. It is noted that the 40-GHz MHEMT SPDT FIS achieves the lowest insertion loss among all the reported MMIC SPDT switches, while the 50-GHz phemt SPDT FIS also demonstrates the lowest insertion loss compared with the other reported phemt SPDT switches in standard HEMT MMIC processes. Fig. 14. Chip photograph of the V -band phemt reduce-sized filter-integrated SPDT switch with a chip size of mm. has an insertion loss, return loss and isolation better than 1.5, 10, and 22 db, respectively, from 40 to 60 GHz. The measurement results agree well with the simulation results. The circuit VI. CONCLUSION In this paper, the concept of the reduced-size filter-integrated switch is illustrated. The systematic design approach is presented so that the design parameters of the SPDT FIS can be determined by applying the filter synthesis and size reductioxn method. The improvement of insertion loss and isolation are also demonstrated using this technique. Moreover, compared

10 LEE et al.: LOW INSERTION-LOSS SPDT REDUCED-SIZE QUARTER-WAVELENGTH HEMT BANDPASS FILTER INTEGRATED SWITCHES 3037 with conventional traveling wave topology, the size reduction method enables a higher operating frequency. The 40-GHz phemt MMIC SPDT FIS achieves 1-dB insertion loss and 32-dB isolation, while 50-GHz phemt MMIC SPDT FIS achieves 1.5-dB insertion loss and 20-dB isolation. To the best of our knowledge, these two MMIC SPDT FIS demonstrate the lowest insertion losses among all the reported MMW SPDT switches in the standard MMIC HEMT processes. REFERENCES [1] J. Lee, Z.-M Tsai, and H. Wang, A band-pass filter-integrated switch using field-effect transistors and its power analysis, in IEEE MTT-S Int. Microwave Symp. Dig., San Francisco, CA, 2006, pp [2] S. F. Chao, C.-H. Wu, Z.-M. Tsai, H. Wang, and C.-H. Chen, Electronically switchable bandpass filters using loaded stepped-impedance resonators, IEEE Trans. Microw. Theory Tech., vol. 54, no. 12, pp , Dec [3] Z. M. Tsai, Y. S. Jiang, J. Lee, K. Y. Lin, and H. Wang, Analysis and design of bandpass single-pole double-throw FET filter-integrated switches, IEEE Trans. Microw. Theory Tech., vol. 55, no. 8, pp , Aug [4] J. Lee, R.-B. Lai, C.-C. Chiong, K.-Y. Lin, and H. Wang, A Q-band low loss reduced-size filter-integrated SPDT using 0.15-m mhemt technology, in IEEE MTT-S Int. Microwave Symp. Dig., Atlanta, GA, 2008, pp [5] T. Hirota, A. Minakawa, and M. Muraguchi, Reduced-size branchline and rat-race hybrids for uniplanar MMIC s, IEEE Trans. Microw. Theory Tech., vol. 38, no. 3, pp , Mar [6] Sonnet User s Manual, Sonnet Software Inc., Liverpool, NY, [7] WIN semiconductors GaAs 0.15 m phemt Model Handbook, WIN Inc., Taipei, Taiwan, [8] Z.-M. Tsai, M.-C. Yeh, H.-Y. Chang, M.-F. Lei, K.-Y. Lin, C.-S. Lin, and H. Wang, FET-integrated CPW and the application in filter synthesis design method on traveling-wave switch above 100 GHz, IEEE Trans. Microw. Theory Tech., vol. 54, no. 5, pp , May [9] K.-Y. Lin, Y.-J. Wang, D.-C. Niu, and H. Wang, Millimeter-wave MMIC single-pole double-throw passive HEMT switches using impedance-transformation networks, IEEE Trans. Microw. Theory Tech., vol. 51, no. 4, pp , Apr [10] M. Madihian, L. Desclos, K. Maruhashi, K. Onda, and M. Kuzuhara, A sub-nanosecond resonant-type monolithic T/R switch for millimeter-wave systems applications, IEEE Trans. Microw. Theory Tech., vol. 46, no. 7, pp , Jul [11] K.-Y. Lin, W.-H. Tu, P.-Y. Chen, H.-Y. Chang, H. Wang, and R.-B. Wu, Millimeter-wave MMIC passive HEMT switches using travelingwave concept, IEEE Trans. Microw. Theory Tech., vol. 52, no. 8, pp , Aug [12] G. L. Lan, D. L. Dunn, J. C. Chen, C. K. Pao, and D. C. Wang, A high performance V -band monolithic FET transmit-receive switch, in IEEE Microw. Millimeter-wave Monolithic Circuits Symp. Dig., New York, Jun. 1988, pp [13] J. Kim, W. Ko, S.-H. Kim, J. Jeong, and Y. Kwon, A high-performance GHz MMICSPDT switch using fet-integrated transmission line structure, IEEE Microw. Wireless Compon. Lett., vol. 13, no. 12, pp , Dec Jeffrey Lee (S 06) was born in Buffalo, NY, in He received the B.S. degree in electronic engineering and the M.S. degree in communication engineering from National Taiwan University, Taipei, in 2006 and 2008, respectively. He is currently a Research Assistant with the Graduate Institute of Communication Engineering, National Taiwan University. His research interests include the design of monolithic microwave integrated circuits and the theory of microwave circuits. Ruei-Bin Lai (S 07) was born in Taoyuan, Taiwan, in He received the B.S. degree in electrical engineering from National Taiwan University, Taipei, in He is currently working toward the M.S. degree at the Graduate Institute of Communication Engineering, National Taiwan University. His research interests include the design of monolithic microwave integrated circuits and the theory of microwave circuits. Mr. Lai was the recipient of Creative Research Award of National Science Council, R.O.C. (2006). He was one of the recipients of 2007 MTT-S Undergraduate Scholarship. Chung-Chun Chen (S 03) was born in Taipei, Taiwan, in He received the M.S. degree in communication engineering from National Taiwan University, Taipei, in He is currently working toward the Ph.D. degree in electronics engineering at National Taiwan University. His current research interests focus on millimeterwave integrated circuit designs for high-speed communication systems. Chin-Shen Lin (S 01) was born in Hsinchu, Taiwan, on February 7, He received the B.S. degree in electrical engineering from National Taiwan University, Taipei, in 2001 and the Ph.D. degree from t the Graduate Institute of Communication Engineering, National Taiwan University in His main research is on monolithic microwave/millimeter-wave circuit design. Kun-You Lin (S 00 M 04) was born in Taipei, Taiwan, in He received the B.S. degree in communication engineering from National Chiao Tung University, Hsinchu, Taiwan, in 1998 and the Ph.D. degree in communication engineering from National Taiwan University, Taipei, in From August 2003 to March 2005, he was a Post-Doctoral Research Fellow with the Graduate Institute of Communication Engineering, National Taiwan University. From May 2005 to July 2006, he was an Advanced Engineer with the Sunplus Technology Company Ltd., Hsinchu. In July 2006, he joined the faculty of the Department of Electrical Engineering and Graduate Institute of Communication Engineering, National Taiwan University, as an Assistant Professor. His research interests include the design and analysis of microwave/rf crcuits. Dr. Lin is a member of Phi Tau Phi. Chau-Ching Chiong was born in Taipei, Taiwan, in He received the B.S. and M.S. degrees in electrical engineering from National Taiwan University, Taipei, in 1997 and 1999, respectively, and the Ph.D. degree in astronomy from the University of Bonn, Bonn, Germany, in He then joined the Institute of Astronomy and Astrophysics, Academia Sinica (ASIAA), Taiwan, where he is involved in the research and development of the Atacama Large Millimeter Array (ALMA) project. His current research interests include large-array and focal-plane array receiver systems and very low noise systems in radio astronomical applications using monolithic microwave integrated circuits.

11 3038 IEEE TRANSACTIONS ON MICROWAVE THEORY AND TECHNIQUES, VOL. 56, NO. 12, DECEMBER 2008 Huei Wang (S 83 M 87 SM 95 F 06) was born in Tainan, Taiwan, on March 9, He received the B.S. degree from National Taiwan University, Taipei, in 1980 and the M.S. and Ph.D. degrees from Michigan State University, East Lansing, in 1984 and 1987, respectively, all in electrical engineering. During his graduate study, he was engaged in the research on theoretical and numerical analysis of electromagnetic radiation and scattering problems. He was also involved in the development of microwave remote detecting/sensing systems. He joined Electronic Systems and Technology Division of TRW Inc. since He has been an MTS and Staff Engineer responsible for MMIC modeling of CAD tools, MMIC testing evaluation and design and became the Senior Section Manager of MMW Sensor Product Section in RF Product Center. He visited the Institute of Electronics, National Chiao-Tung University, Hsin-Chu, Taiwan, in 1993 to teach MMIC related topics and returned to TRW in He joined the faculty of the Department of Electrical Engineering, National Taiwan University, Taipei, as a Professor in February He is currently the Director of Graduate Institute of Communication Engineering of National Taiwan University. Prof. Wang is a member of Phi Kappa Phi and Tau Beta Pi. He received the Distinguished Research Award of National Science Council, ROC ( ). He was also elected as the Richard M. Hong Endowed Chair Professor of National Taiwan University from 2005 to He has been appointed as an IEEE Distinguished Microwave Lecturer for the term of He was the recipient of the Academic Achievement Award from the Ministry of Education, R.O.C., in 2007.