Publications

International Journal Articles

1. Z. Chen, H. Dong, Z. Chen, W. Choi, J.-X. Chen, K. K. O, and W. Hong, "380-GHz Third Harmonic Signal Generation Using Differentially Pumped Varactors in a CMOS Voltage Controlled Oscillator," in IEEE Transactions on Circuits and Systems I: Regular Papers, doi: 10.1109/TCSI.2024.3519170.

2. W. Choi and K. K. O, “Enabling Applications of Electromagnetic Waves at 0.3–1.0 THz Using Silicon Electronic Integrated Circuits,” ACS Photonics, Mar. 2024, doi: 10.1021/acsphotonics.3c01129.

3. P. R. Byreddy, Y. Zhu, S. Ghosh, H. S. Bakshi, W. S. Portillo, J. P. Van Marter, K. K. O, W. Choi, "Array of 296-GHz CMOS Concurrent Transceiver Pixels With Phase and Amplitude Extraction Circuits for Improving Reflection-Mode Imaging Resolution," in IEEE Transactions on Terahertz Science and Technology (TTHZ), vol. 14, no. 2, pp. 216-227, March 2024, doi: 10.1109/TTHZ.2024.3350515.

4. K. K. O, W. Choi, and R. Han, “Perspective on active submillimeter electromagnetic wave imaging using CMOS integrated circuits technologies,” Journal of Applied Physics, vol. 133, no. 15, p. 150903, Apr. 2023, doi: 10.1063/5.0143622.

5. P. R. Byreddy, W. E. Sosa, Y. Zhu, Z. Chen, B. Pouya, W. Choi, and K. K. O, "Lens-less Short-Range Reflection-Mode Imaging at 275 GHz Using CMOS Concurrent Transceivers," in IEEE Sensors Letters, vol. 7, no. 2, pp. 1-4, Feb. 2023, Art no. 3500204, doi: 10.1109/LSENS.2023.3239804.

6. K. K. O, W. Choi, Y. Zhu and H. Guo, "CMOS Platform for Everyday Applications Using Sub-Millimeter Electromagnetic Waves," in IEEE Open Journal of the Solid-State Circuits Society, 2022, doi: 10.1109/OJSSCS.2022.3222121.

7. W. Raza, E. Abele, J. O'Hara, B. Sadr, P. LoPresti, A. Imran, W. Choi, I. Song, S. Altunc, O. Kegege, and S. Ekin, "Towards a Hybrid RF/Optical Lunar Communication System (LunarComm)," in IEEE Network, vol. 36, no. 6, pp. 76-83, November/December 2022, doi: 10.1109/MNET.103.2100419.

8. Y. Zhu, P. R. Byreddy, K. K. O, and W. Choi, "426-GHz Concurrent Transceiver Pixel in 65-nm CMOS for Active Imaging," in TTHZ, vol. 12, no. 5, pp. 446-456, Sept. 2022, doi: 10.1109/TTHZ.2022.3183159.

9. Z. Chen, W. Choi and K. K. O, "300-GHz Double-Balanced Up-Converter Using Asymmetric MOS Varactors in 65-nm CMOS," in IEEE Journal of Solid-State Circuits (JSSC), vol. 57, no. 8, pp. 2336-2347, Aug. 2022, doi: 10.1109/JSSC.2022.3171545.

10. A. Kachroo, C. A. Thornton, M. A. R. Sarker, W. Choi, H. Bai, I. Song, J. O'Hara, and S. Ekin ,  "Emulating UAV Motion by Utilizing Robotic Arm for mmWave Wireless Channel Characterization," in IEEE Transactions on Antennas and Propagation, vol. 69, no. 10, pp. 6691-6701, Oct. 2021, doi: 10.1109/TAP.2021.3069484.

11. H. S. Bakshi, S. Dong, I. Momson, D. Chacon, Z. Chen, W. Choi, A. J. Blanchard, and K. K. O, "180-GHz Broadside Radiation Bond-Wire Antenna for Short-Range Wireless Communication," in IEEE Transactions on Components, Packaging and Manufacturing Technology, vol. 11, no. 3, pp. 530-532, March 2021, doi: 10.1109/TCPMT.2021.3053558.

12. S. Dong, I. Momson, S. Kshattry, P. Yelleswarapu, W. Choi and K. K. O, "A 10-Gb/s 180-GHz Phase-Locked-Loop Minimum Shift Keying Receiver," in JSSC,  vol. 56, no. 3, pp. 681-693, March 2021, doi: 10.1109/JSSC.2020.3032972.

13. Q. Zhong, W. Choi and K. K. O, "Terahertz Even-Order Subharmonic Mixer Using Symmetric MOS Varactors," in JSSC, vol. 56, no. 2, pp. 355-366, Feb. 2021, doi: 10.1109/JSSC.2020.3024177.

14. Z. Chen, W. Choi and K. K. O., "300-GHz 2nd-Order Subharmonic Upconversion Mixer Using Symmetric MOS Varactors in 65-nm CMOS," in IEEE Solid-State Circuits Letters (SSCL), vol. 3, pp. 538-541, 2020, doi: 10.1109/LSSC.2020.3036804.

15. E. Guerrero, A. Polednik, M. Ecker, A. Joshi‐Imre, W. Choi, G. Gutierrez‐Heredia, W. E. Voit, J. Maeng, "Indium–Gallium–Zinc Oxide Schottky Diodes Operating across the Glass Transition of Stimuli‐Responsive Polymers," in Adv. Electron. Mater. 2020, 1901210. doi: 10.1002/aelm.201901210

16. Z. Chen, Z. Chen, W. Choi and K. K.O., "610-GHz Fourth Harmonic Signal Reactively Generated in a CMOS Voltage Controlled Oscillator Using Differentially Pumped Varactors," in SSCL, vol. 3, pp. 46-49, 2020, doi: 10.1109/LSSC.2020.2978150.

17. H. S. Bakshi, P. R. Byreddy, K. K. O, A. Blanchard, M. Lee, E. Tuncer, W. Choi, "Low-Cost Packaging of 300 GHz Integrated Circuits With an On-Chip Patch Antenna," in IEEE Antennas and Wireless Propagation Letters, vol. 18, no. 11, pp. 2444-2448, Nov. 2019. doi: 10.1109/LAWP.2019.2943371 

18. Z. Chen, S. Dong, Z. Chen, W. Choi, S. Kshattry, I. Momson, Q. Zhong, K. K. O, "Generation of High Data Rate MSK-Modulated 180-GHz Signals," in IEEE Microwave and Wireless Components Letters (MWCL), vol. 29, no. 11, pp. 757-760, Nov. 2019. doi: 10.1109/LMWC.2019.2940552

19. (invited) K. K. O, W. Choi, Q. Zhong, N. Sharma, Y. Zhang, R. Han, Z. Ahmad, D. Kim, S. Kshattry, I. R. Medvedev, D. J Larry, H. Nam, P. Raskin, I. Kim , “Opening Terahertz for Everyday Applications,” IEEE Communications Magazine, vol. 57, no. 8, pp. 70–76, Aug. 2019. [doi:10.1109/MCOM.2019.1800909]

20. (review) J. F. O’Hara, S. Ekin, W. Choi, and I. Song, “A Perspective on Terahertz Next-Generation Wireless Communications,” Technologies, vol. 7, no. 2, p. 43, Jun. 2019.  [doi:10.3390/technologies7020043]

21. W. Choi, P. R. Byreddy, Z. Chen, A. J. Chen, A. J. Newman, and K. K. O, “450×580 µm2 Pixel incorporating TX and coherent RX in CMOS for mm-wave active imaging using a single reflector,” IET Electron. Lett. (EL), vol. 54, no. 16, pp. 982–984, 2018. [doi:10.1049/el.2018.1086]

22. D. Shim, W. Choi, J. W. Lee, and K. K. O, “Self-Dynamic and Static Biasing for Output Power and Efficiency Enhancement of Complementary Antiparallel Diode Pair Frequency Tripler,” MWCL, vol. 27, no. 12, pp. 1110–1112, Dec. 2017.  doi: 10.1109/LMWC.2017.2757845

23. S. Kshattry, W. Choi, C. Yu, and K. K. O, “Compact Diode Connected MOSFET Detector for On-Chip Millimeter-Wave Voltage Measurements,” MWCL, vol. 26, no. 5, pp. 349–351, May 2016. doi: 10.1109/LMWC.2016.2548365

24. J. Zhang, N. Sharma, W. Choi, D. Shim, Q. Zhong, and K. K. O, “85-to-127 GHz CMOS Signal Generation Using a Quadrature VCO With Passive Coupling and Broadband Harmonic Combining for Rotational Spectroscopy,” JSSC, vol. 50, no. 6, pp. 1361–1371, June 2015. doi: 10.1109/JSSC.2015.2416312

25. M. Seo, H. Lee, J. Gu, H. Kim, J. Ham, W. Choi, Y. Yun, K. K. O, and Y. Yang, “High-Efficiency Power Amplifier Using an Active Second-Harmonic Injection Technique Under Optimized Third-Harmonic Termination,” IEEE Trans. Circ. Syst. II: Express Briefs, vol. 61, no. 8, pp. 549–553, Aug. 2014. doi: 10.1109/TCSII.2014.2327382

26. C. Lee, W. Choi, R. Han, H. Shichijo, and K. K. O, “Broadband Root-Mean-Square Detector in CMOS for On-Chip Measurements of Millimeter-Wave Voltages,” IEEE Electron. Device Lett., vol. 33, no. 6, pp. 752 –754, Jun. 2012. doi: 10.1109/LED.2012.2190258

27. J. Kim, W. Choi, A. S. Quraishi, and Y. Kwon, "Millimeter-wave High-Linear CMOS Low-Noise Amplifier Using Multiple-Gate Transistors," ETRI Journal, Vol. 33, No. 3, pp. 462-465, Jun. 2011.  doi: 10.4218/etrij.11.0210.0235 

28. W. Choi, K. Park, Y. Kim, K. Kim, and Y. Kwon, "A V-band switched Beam-Forming Antenna Module Using Absorptive Switch Integrated with 4x4 Butler Matrix in 0.13-μm CMOS," IEEE Trans. Microw. Theory Tech. (TMTT), Vol. 58, No. 12, pp. 4052-4059, Dec. 2010. doi: 10.1109/TMTT.2010.2086472 

29. W. Choi, K. Kim, and Y. Kwon, "Ultra-Low-Power Series-Feedback Frequency Divider using 0.15-μm GaAs pHEMT’s at W-Band," MWCL, Vol. 20, No. 11, pp. 634-636, Nov. 2010. doi: 10.1109/LMWC.2010.2067207

30. W. Choi, G. Jung, J. Kim, and Y. Kwon, “Scalable Small-Signal Modeling of RF CMOS FET Based on 3-D EM-Based Extraction of Parasitic Effects and Its Application to Millimeter-Wave Amplifier Design,” TMTT, vol. 57, No. 12, pp. 3345-3353., Dec. 2009. doi: 10.1109/TMTT.2009.2034067

31. S. Song, Y. Kim, W. Choi, Y. Kwon, and K.-S. Seo, “A V-Band Parallel-Feedback Oscillator with a Micromachined Cavity Integrated on a Thin-Film Substrate,” MWCL, vol. 19, no. 2, pp. 107-109, Feb. 2009. doi: 10.1109/LMWC.2008.2011334 

32. J. Park, E. S. Shim, W. Choi, Y. Kim, Y. Kwon, and D. Cho, “A Non-Contact-Type RF MEMS Switch for 24-GHz Radar Applications,” IEEE J. Microelectromech. Sys., vol. 18, no. 1, pp. 163–173, Feb. 2009. doi: 10.1109/JMEMS.2008.2011124 

33. C. Lee, W. Choi, J. Kim, and Y. Kwon, “A 77 GHz 3-stage low noise amplifier with cascode structure utilizing positive feedback network using 0.13 μm CMOS process,” J. Semic. Tech. and Sci., vol. 8, no. 4, pp. 289–294, 2008. doi: 10.5573/JSTS.2008.8.4.289 

34. J. Jeong, S.W. Kim, W. Choi, K.-S. Seo, and Y. Kwon, “A distributed amplifier with 12.5-dB gain and 82.5-GHz bandwidth using 0.1 μm GaAs metamorphic HEMTs,” Microw. Optical Tech. Lett., vol. 49, No. 11, pp. 2873-2875, Nov. 2007. doi: 10.1002/mop.22844

35. W. Choi and Y. Kwon, “Phase Locked Loop Sub-Circuits for 24 GHz Signal Generation in 0.5 μm SiGe HBT technology,” J. Semic. Tech. Sci., vol. 7, no. 4, p. 281, 2007. doi: 10.5573/JSTS.2007.7.4.281 

36. H. Kim, W. Choi, and Y. Kwon, “V-band MMIC oscillator array,” EL, vol. 41, No. 8, pp. 481-483, Apr. 2005. doi: 10.1049/el:20050082

37. J. Jeong, S. Kim, W. Choi, H. Noh, K. Lee, K.-S. Seo, and Y. Kwon, “W-band divide-by-3 frequency divider using 0.1 μm InAlAs/InGaAs metamorphic HEMT technology,” EL, vol. 41, No. 18, pp. 1005-1006, Sep. 2005.  doi: 10.1049/el:20052191 

38. C.-W. Baek, S. Song, J.-H. Park, S. Lee, J.-M. Kim, W. Choi, Changyul-Cheon, Y.-K. Kim, and Y. Kwon, “A V-band micromachined 2-D beam-steering antenna driven by magnetic force with polymer-based hinges,” TMTT, vol. 51, no. 1, pp. 325–331, Jan. 2003. doi: 10.1109/TMTT.2002.806516 

39. J.-H. Park, H.-T. Kim, W. Choi, Y. Kwon, and Y.-K. Kim, “V-band reflection-type phase shifters using micromachined CPW coupler and RF switches,” IEEE J. Microelectromech. Sys., vol. 11, no. 6, pp. 808–814, Dec. 2002. doi: 10.1109/JMEMS.2002.805042 

International Conference Papers

1. H. Guo, S. Ghosh, F. Zhang, S. Lee, W. Choi, S. Dong, and K. K. O, "10-GSymbols/s Supply Modulated 250-GHz SiGe HBT Transmitter RF Front-End with 6.8-dBm Peak Modulated Power," 2024 IEEE BiCMOS and Compound Semiconductor Integrated Circuits and Technology Symposium (BCICTS), Fort Lauderdale, FL, USA, 2024, pp. 181-184, doi: 10.1109/BCICTS59662.2024.10745659.

2. J. Hu, J. Stine, W. Choi, and E. Dyke, “Research Experiences for Teachers on Chip Design,” in 2024 IEEE International Symposium on Circuits and Systems (ISCAS), May 2024, pp. 1–5. doi: 10.1109/ISCAS58744.2024.10558044.

3. S. Azmeen-ur-Rahman, M. O. Hasna, S. Ekin, and W. Choi, “Two-Port Characterization of Symmetric Varactors in 65-nm CMOS Process for Mixer Applications,” in 2023 IEEE Texas Symposium on Wireless and Microwave Circuits and Systems (WMCS), Apr. 2023, pp. 1–4. doi: 10.1109/WMCS58822.2023.10194281.

4. H. Mehraban, W.-S. Park, H.-B. Jo, S.-M. Choi, D.-H. Kim, S.-K. Kim, J. Yun, T. Kim, W. Choi, "A W-Band Low-Noise Amplifier in 50-nm InP HEMT Technology," in WMCS, Apr. 2023, pp. 1–4. doi: 10.1109/WMCS58822.2023.10194275.

5. K. Strecker, W. Choi, J. O’Hara, "A Wideband Millimeter-Wave Communication and Sensing Testbed for 75-500 GHz," in WMCS, Apr. 2023, pp. 1–5. doi: 10.1109/WMCS58822.2023.10194272.

6. W. Choi, Y. Zhu, P. R. Byreddy, S. Dong, K. K. O, "430-GHz Concurrent Transceiver Array in CMOS for Power-efficient High-Resolution Stand-off Imaging", 2023 Government Microcircuit Applications and Critical Technology Conference (GOMACTech), Mar. 2023.

7. H. S. Cankurtaran, A. Kachroo, W. Choi, J. O'Hara, S. Yarkan, K. A. Qaraqe, M. O. Hasna, and S. Ekin, "Propeller Effects on mmWave UAV Channels: A Statistical and Empirical Modeling Study," 2022 IEEE International Black Sea Conference on Communications and Networking (BlackSeaCom), 2022, pp. 30-35, doi: 10.1109/BlackSeaCom54372.2022.9858315.

8. M. T. Anas, S. Azmeen-ur-Rahman and W. Choi, "A 410-GHz Detector using AC-coupled Substrate-Integrated Waveguide Slot Antenna in CMOS," WMCS, 2022, pp. 1-5, doi: 10.1109/WMCS55582.2022.9866391.

9. Y. Zhu, P. R. Byreddy, S. Dong, K. K. O and W. Choi, "A 430GHz CMOS Concurrent Transceiver Pixel Array for High Angular Resolution Reflection-Mode Active Imaging," 2022 IEEE International Solid-State Circuits Conference (ISSCC), 2022, pp. 1-3, doi: 10.1109/ISSCC42614.2022.9731698.

10. C. Thornton, A. Kachroo, H. Bai, S. Ekin, and W. Choi, "De-embedding Motion Artifacts from Robotic Arm Assisted Propagation Measurements," WMCS, 2021, pp. 1-6, doi: 10.1109/WMCS52222.2021.9493296.

11. Z. Chen, W. Choi and K. K. O, "23.1 270-to-300GHz Double-Balanced Parametric Upconverter Using Asymmetric MOS Varactors and a Power-Splitting-Transformer Hybrid in 65nm CMOS," ISSCC, 2021, pp. 324-326, doi: 10.1109/ISSCC42613.2021.9365953.

12. P. R. Byreddy, Y. Zhu, H. S. Bakshi, K. K. O and W. Choi, "287-GHz CMOS Transceiver Pixel Array in a QFN Package for Active Imaging," 2020 IEEE Asian Solid-State Circuits Conference (A-SSCC), 2020, pp. 1-4, doi: 10.1109/A-SSCC48613.2020.9336111.

13. I. Momson, S. Dong, P. Yelleswarapu, W. Choi and K. K. O, "315-GHz Self-Synchronizing Minimum Shift Keying Receiver in 65-nm CMOS," 2020 IEEE Symposium on VLSI Circuits (VLSIC), Honolulu, HI, USA, 2020, pp. 1-2, doi: 10.1109/VLSICircuits18222.2020.9162779.

14. N. Sharma, Q. Zhong, W. Choi, J. Zhang, Z. Chen, Z. Ahmad, I. R. Medvedev, D. J. Lary, H.-J. Nam, P. Raskin, I. Kim, K. K. O., "Complementary metal oxide semiconductor integrated circuits for rotational spectroscopy," Proc. SPIE 11390, Next-Generation Spectroscopic Technologies XIII, 113900K (19 May 2020); https://doi.org/10.1117/12.2557169

15. S. Dong, I. Momson, S. Kshattry, P. Yelleswarapu, W. Choi and K. K. O, "A Wideband 180-GHz Phase-Locked-Loop Based MSK Receiver," 2020 IEEE Custom Integrated Circuits Conference (CICC), Boston, MA, USA, 2020, pp. 1-4, doi: 10.1109/CICC48029.2020.9075939.

16. (invited) S. Kshattry, C.-K. Yu, C.-L. Wu, Y. Yun, C. Lee, C.-Y. Cha, W. Choi, N. Preisler, K. K. O, "High-Impedance, Broadband and Compact RMS Detectors for On-Chip Measurements of Millimeter Wave Voltages for Built-In Self-Testing and Debugging," 2020 IEEE 20th Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems (SiRF), San Antonio, TX, USA, 2020, pp. 22-25, doi: 10.1109/SIRF46766.2020.9040184.

17. (invited) W. Choi, Y. Zhu, P. R. Byreddy, Z. Chen, Z. Chen, A. J. Newman and K. K. O, "CMOS Transceiver Pixels for Terahertz Imaging," 2019 IEEE International Symposium on Radio-Frequency Integrated Technology (RFIT), Aug. 2019, Nanjing, China. doi: 10.1109/RFIT.2019.8929129

18. Y. Zhu, P. R. Byreddy, K. K. O, and W. Choi, “426-GHz Imaging Pixel Integrating a Transmitter and a Coherent Receiver with an Area of 380×470μm2 in 65-nm CMOS,” VLSIC, June 2019, pp. C18–C19. [doi:10.23919/VLSIC.2019.8778039]

19. (invited) W. Choi, D. Kim, Z. Ahmad, P Byreddy, Y. Zhu, J. Newman, and K. K. O, “CMOS Circuits for THz Imaging,” in Micro- and Nanotechnology Sensors, Systems, and Applications XI (SPIE DCS), 2019, vol. 10982, p. 1098231. [doi:10.1117/12.2518654]

20. Q. Zhong, W. Choi, K. K. O, “Terahertz RF Front‐End Employing Even‐Order Subharmonic MOS Symmetric Varactor Mixers in 65‐nm CMOS for Hydration Measurements at 560 GHz,” VLSIC, June 2018. [doi:10.1109/VLSIC.2018.8502297]

21. Q. Zhong, Z. Chen, N. Sharma, S. Kshattry, W. Choi, and K. O. Kenneth, “300-GHz CMOS QPSK transmitter for 30-Gbps dielectric waveguide communication,” CICC, Apr. 2018, pp. 1–4. [doi:10.1109/CICC.2018.8357053]

22. (invited) Q. Zhong, W. Choi, ..., and K. K. O, “CMOS Terahertz Receivers,” CICC, Apr. 2018. [doi:10.1109/CICC.2018.8357054]

23. (invited) K. K. O, Z. Ahmad, W. Choi et al., “(Keynote) Devices in CMOS for Terahertz Circuits and Systems,” Electrochemical Society Trans., vol. 80, no. 4, pp. 3–15, Aug. 2017. doi: 10.1149/08004.0003ecst

24. (invited) Z. Ahmad, W. Choi, ..., and K. K. O, “Devices and Circuits in CMOS for THz Applications,” 2016 IEEE International Electron Devices Meeting (IEDM), Dec. 2016. doi: 10.1109/IEDM.2016.7838509 

25. N. Sharma, Q. Zhong, Z. Chen, W. Choi, J. P. McMillan, C. F. Neese, R. Schueler, I. Medvedev, F. De Lucia, K. K. O, “200-280GHz CMOS RF Front-End of Transmitter for Rotational Spectroscopy,” 2016 Symp. VLSI Tech. (VLSIT), June 2016. doi: 10.1109/VLSIT.2016.7573400 

26. W. Choi, and K. K. O, “Kelvin Inductance and Resistance Measurements Using an AC Source and DC Voltmeters,” 2016 IEEE MTT-S International Microwave Symposium (IMS), May 2016. doi: 10.1109/MWSYM.2016.7540355 

27. Q. Zhong, W. Choi, N. Sharma, Z. Ahmad, J. P. McMillan, C. F. Neese, F. C. De Lucia, and K. K. O, “225–280GHz Receiver for Rotational Spectroscopy,” 2016 IEEE Radio Frequency Integrated Circuits Symposium (RFIC), May 2016. doi: 10.1109/RFIC.2016.7508310 

28. N. Sharma, W. Choi, K. K. O, “160–310GHz Frequency Doubler in 65-nm CMOS with 3-dBm Peak Output Power for Rotational Spectroscopy,” RFIC, May 2016. doi: 10.1109/RFIC.2016.7508282 

29. Q. Zhong, W. Choi, C. Miller, R. Henderson, K. K. O, “A 210-to-305GHz CMOS Receiver for Rotational Spectroscopy”, ISSCC, Feb. 2016. doi: 10.1109/ISSCC.2016.7418089 

30. (invited) Z. Ahmad, D.-Y. Kim, R. Han, W. Choi, and K. K. O, “Terahertz imaging circuits in CMOS,” Asia-Pacific Microw. Conf. (APMC), Dec. 2015. doi: 10.1109/APMC.2015.7411757 

31. W. Choi, Z. Ahmad, A. Jha, J.-Y. Lee, I. Kim, and K. K. O, “410-GHz CMOS Imager Using a 4th Sub-harmonic Mixer with Effective NEP of 0.3 fW/Hz0.5 at 1-kHz Noise Bandwidth” VLSIC, Jun. 2015. doi: 10.1109/VLSIC.2015.7231299 

32. T. Xi, S. Huang, S. Guo, P. Gui, J. Zhang, W. Choi, D. Huang, K. O, "A new compact high-efficiency mmWave power amplifier in 65 nm CMOS process," IMS, 2015, pp. 1-4.

33. S. Guo, T. Xi, P. Gui, J. Zhang, W. Choi, K. O, Y. Fan, D. Huang, R. Gu, and M. Morgan, “54 GHz CMOS LNAs with 3.6 dB NF and 28.2 dB gain using transformer feedback Gm-boosting technique,” ASSCC, pp. 185–188, Nov. 2014. doi: 10.1109/ASSCC.2014.7008891 

34. N. Sharma, J. Zhang, Q. Zhong, W. Choi, J. P. McMillan, C. F. Neese, F. C. De Lucia, and K. K. O., “85-to-127 GHz CMOS transmitter for rotational spectroscopy,” CICC, Sept. 2014. doi: 10.1109/CICC.2014.6946140 

35. W. Choi, S. Nelson, D. Ferwalt, R. Mongia, H. Shichijo, K. K. O, “Three-harmonic Time-domain Load-pull Measurement System with the 40-GHz Maximum Third Order Harmonic Frequency for Nonlinear Device Characterization,” 82th Microw. Measurement Symp. (ARFTG), Nov. 2013. doi: 10.1109/ARFTG-2.2013.6737344 

36. W. Choi, D. Y. C. Lie, J. Lopez, D. Ma, R. Mongia, S. Nelson, K. K. O, S. Shichijo, M. Walker, R. Bondade, M. Song, “Wideband Class J High Efficiency Envelope Tracked Power Amplifiers,” 2013 GOMACTech Conf., Mar. 2013

37. Y. Park, Y. Kim, W. Choi, J. Woo, and Y. Kown, "X-to-K-band Broadband Watt-level Power Amplifier Using Stacked-FET Unit Cells," RFIC, June 2011. doi: 10.1109/RFIC.2011.5940620 

38. K. Park, W. Choi, Y. Kim, K. Kim, and Y. Kwon, “A V-band Switched Beam-Forming Network Using Absorptive SP4T Switch Integrated with 4x4 Butler Matrix in 0.13-μm CMOS,” IMS, May 2010. doi: 10.1109/MWSYM.2010.5515849 

39. J. Kim, W. Choi, Y. Park, and Y. Kwon, “60 GHz broadband image rejection receiver using varactor tuning,” RFIC, pp. 381-384, May 2010. doi: 10.1109/RFIC.2010.5477351 

40. G. Jung, W. Choi, and Y. Kwon, “Scalable small-signal modeling of RF CMOS FET based on 3-D EM-based extraction of parasitic effects,” IMS, pp. 873-876, June 2009. doi: 10.1109/MWSYM.2009.5165836 

41. S.-W. Kim, Y.-M. Koh, W. Choi, H.-T. Kim, Y. Kwon, and K. S. Seo, "W-band low-noise amplifier with 50 nm In0.8GaP/In0.4AlAs/In0.35GaAs metamorphic HEMT," Int. Conf. InP and Related Materials, May 2008. doi: 10.1109/ICIPRM.2008.4702951 

42. E. S. Shim, J. Park, W. Choi, Y. Kim, Y. Kwon, J. S. No, S. Nam, and D. Cho, “Hot-Switching Test of Non-Contact Type MEMS Switch,” IMS, pp. 1809–1812, June 2007. doi: 10.1109/MWSYM.2007.380100 

43. K. Kim, W. Choi, S. Kim, G. Seol, K.-S. Seo, and Y. Kwon, “A 77 GHz Transceiver for Automotive Radar System Using a 120nm In0.4AlAs/In0.35GaAs Metamorphic HEMTs,” Comp. Semic. Integ. Circ. Symp. Dig., pp. 201-204, Nov. 2006. doi: 10.1109/CSICS.2006.319963 

44. S. Kim, W. Choi, D. Kim, J. Huh, K. Jang, Y. Kwon, and K.-S. Seo, "77GHz low noise sub block MMICs with 120 nm In0.4AlAs/In0.35GaAs metamorphic HEMTs," Eur. Microw. Integr. Circ. Conf. (EuMIC), pp. 103-106, Sep. 2006. doi: 10.1109/EMICC.2006.282761 

45. W. Choi, C. Cheon, and Y. Kwon, “A V-band MMIC Self Oscillating Mixer Active Integrated Antenna Using a Push-Pull Patch Antenna,” IMS, pp. 630-633, June 2006. doi: 10.1109/MWSYM.2006.249692 

46. S. Song, S. Kim, J. Y. Lee, S. Lee, W. Choi, Y. Kwon, and K.-S. Seo, "Flip-Chip Mounted MMICs Technology using the Modified MCM-D Substrate for Low-Cost W-band Transceiver," IMS, June 2005. doi: 10.1109/MWSYM.2005.1516838 

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