隨著無線通訊技術迅速發展，我們見證了各種創新晶片和相關電路技術的蓬勃發展，這些技術為無線通信開闢了新的應用前景和發展空間。伴隨著製程技術的進步和微型化，越來越多的電路和系統得以有效的整合於單一晶片上。這不僅提高了設計的緊湊性和成本效益，同時也為無線通信系統的性能和功能多樣化帶來了新的機遇。
現今在射頻電路中，壓控震盪器為一個重要的電路，並在多種應用中扮演著關鍵角色，其特點是能夠通過調節輸入電壓來變化輸出頻率。VCO在生成可變頻率信號方面發揮著關鍵作用，這一點對於實現有效的信號調變、頻率合成以及精確的時序控制等功能至關重要。鑒於此，本篇論文將重點介紹三個VCO的設計。
首先設計了一個採用0.18 μm CMOS 製程製造的 LC-tank壓控振盪器 (VCO)。 5.83 GHz 的VCO使用一個八字電感和兩對交叉耦合的nMOS組成振盪器，面積為1.146×0.702 mm2，可調頻範圍為5.8 GHz至6.5 GHz。 在電壓給定 1.2V時，功號為1.2 mW，在1MHz 偏移頻率的相位雜訊為 -110.24 dBc/Hz。 此架構可抑制雜訊耦合、提高共振腔的Q-factor並減少晶片面積。
第二、第三顆晶片採用 0.18 μm CMOS 製程製造的 LC-tank壓控振盪器 (VCO)。 VCO 使用兩個透過變壓器耦合的子 VCO 來形成穩健的雙核心 VCO。 在所提出的結構中，錐形耦合帶迫使兩個耦合帶中的電流方向相同。 第一部分為 5.3 GHz 的 VCO 採用current-reused的結構，其面積為 1.194×0.696 mm2，可調諧範圍為 5.3 GHz 至 7.02 GHz。當電源電壓為 1.1 V 時，相位雜訊在1MHz為 –118.25 dBc/Hz、 FOMT為 –197.37 dBc/Hz。 第二部分為4.3 GHz VCO採用兩個互補的VCO，面積為1.192×0.742mm2，可調諧範圍為4.31 GHz至5.83 GHz。 在 1.2V 電源電壓下，相位雜訊在1MHz為 –121.56dBc/Hz ，FOMT值為-199.53 dBc/Hz。

With the rapid development of wireless communication technology, we have witnessed a variety of innovative chips and related circuit technologies that have opened up new application prospects and room for development for wireless communication. With the advancement of process technology and miniaturization, more and more circuits and systems can be effectively integrated on a single chip. This not only improves the compactness and cost-effectiveness of the design, but also brings new opportunities for the performance and functional diversity of wireless communication systems.

Voltage-controlled oscillators (VCOs) are an important circuit in today's RF circuits and play a key role in many applications, featuring the ability to vary the output frequency by adjusting the input voltage. VCOs play a key role in generating variable frequency signals, which is essential for effective signal modulation, frequency synthesis, and precise timing control. In view of this, this paper will focus on the design of three VCOs.

First, an LC-tank voltage-controlled oscillator (VCO) fabricated on a 0.18 μm CMOS process is designed. The 5.83 GHz VCO uses a primary inductor and with two cross-coupled NMOS pairs for negative resistance generation to form an oscillator with an area of 1.146 × 0.702 mm2 , and can be tuned over the frequency range of 5.8 GHz to 6.5 GHz. At a given voltage of 1.2 V, the Figure of merit is 1.2 mW, and the phase noise at 1 MHz offset is - 110.24 dBc/Hz. This structure suppresses noise coupling, improves the Q-factor of the resonance cavity, and reduces the wafer area.

The second and third chip utilize an LC-tank voltage-controlled oscillator (VCO) fabricated on a 0.18 μm CMOS process. The VCO uses two sub-VCOs coupled through a transformer to form a robust dual-core VCO. In the proposed structure, a tapered coupling band forces the current direction to be the same in both coupling bands. The first part of the 5.3 GHz VCO adopts a current-reused structure with an area of 1.194 × 0.696 mm2 and a tunable range of 5.3 GHz to 7.02 GHz. The FOMT is -197.37 dBc/Hz. The phase noise at 1 MHz is -118.25 dBc/Hz at a voltage of 1.1 V. The second part of the 4.3 GHz VCO uses two complementary VCOs with an area of 1.192 x 0.742 mm2 and a tunable range of 4.31 GHz to 5.83 GHz. The phase noise is -121.56 dBc/Hz at 1 MHz with a supply voltage of 1.2 V. The FOMT is -199.53 dBc/Hz.

[1] N. M. Nguyen and R. G. Meyer, “Start-up and frequency stability in high-frequency oscillators,” IEEE J. Solid-State Circuit, vol. 27, no. 5, pp. 810–820, May 1992.
[2] B. Razavi, Design of Integrated Circuits for Optical Communications, Mc Graw Hill.
[3] P. Yue, C. Ryu, JackLau, T. H. Lee, and S. Wong, “A physical model for planar spiral inductors on silicon,” 1996 International Electron Devices Meeting Technical Digest, pp. 155–158, Dec. 1996.
[4] Y. Sun, W. Deng, H. Jia, Z. Wang, and B. Chi,, "A 4.4-GHz 193.2-dB FoM 8-shaped-inductor based LC-VCO using orthogonal-coupled triple-coil transformer", IEEE Trans. Circuits Syst. II: Express Briefs, vol.69, no.10, pp.4028-4032, 2022.
[5] H. Shin and H. Kim, “Extraction technique of differential second harmonic output in CMOS LC VCO,” IEEE Microw. Wireless Compon. Lett., vol. 17, no. 5, pp. 379–381, May 2007.
[6] E. Hegazi, H. Sjoland, and A. A. Abidi, “A filtering technique to lower LC oscillator phase noise,” IEEE J. Solid-State Circuits, vol. 36, no. 12, pp. 1921–1930, Dec. 2001.
[7] I. Gertman, R. Levinger, S. Bershansky, J. Kadry and G. Horovitz, "A 33% tuning range cross-coupled DCO with “Folded” common mode resonator covering both 5G MMW bands in 16-nm CMOS FinFet," 2020 15th European Microwave Integrated Circuits Conference (EuMIC), Utrecht, Netherlands, 2021, pp. 109-112.
[8] D. Fathi and A. Nejad, "Ultra-low power, low phase noise 10 GHz LC VCO in the subthreshold regime," Circuits and Systems, Vol. 4 No. 4, 2013, pp. 350-355.
[9] Y. Peng et al., "A harmonic-tuned VCO with an intrinsic-high-Q F23 inductor in 65-nm CMOS," IEEE Microw. Wireless Compon. Lett., vol. 30, no. 10, pp. 981-984, Oct. 2020, doi: 10.1109/LMWC.2020.3016300.
[10] Z. Zong, G. Mangraviti, and P. Wambacq, “Low 1/f3 noise corner LC VCO design using flicker noise filtering technique in 22 nm FD-SOI,” IEEE Trans. Circuits Syst. I, Reg. Papers, vol. 67, no. 5, pp. 1469–1480, May 2020.
[11] H. Tong, S. Cheng, Y.-C. Lo, A. Karsilayan, and J. Silva-Martinez, “An LC quadrature VCO using capacitive source degeneration coupling to eliminate bi-modal oscillation,” IEEE Trans. Circuits Syst. I, Reg. Papers, vol. 59, no. 9, pp. 1871–1879, Sep. 2012.
[12] S. L. J. Gierkink, S. Levantino, R. C. Frye, C. Samori, and V. Boccuzzi, “A low-phase-noise 5-GHz CMOS quadrature VCO using superharmonic coupling,” IEEE J. Solid-State Circuits, vol. 38, no. 7, pp. 1148–1154, Jul. 2003.
[13] K.-W. Kim, H.-J. Chang, Y.-M. Kim, and T.-Y. Yun, “A 5.8 GHz low-phase-noise LC-QVCO using splitting switched biasing technique,” IEEE Microw. Wireless Compon. Lett., vol. 20, no. 6, pp. 337–339, Jun. 2010.
[14] C.-Y. Jeong and C.-S. Yoo, “5-GHz low-phase noise CMOS quadrature VCO,” IEEE Microw. Wireless Compon. Lett., vol. 16, no. 11, pp. 609–611, Nov. 2006.
[15] D. B. Leeson, "Oscillator phase noise: A 50-Year Review," in IEEE Transactions on Ultrasonics, Ferroelectrics, and Frequency Control, vol. 63, no. 8, pp. 1208-1225, Aug. 2016, doi: 10.1109/TUFFC.2016.2562663.
[16] A. Chorti and M. Brookes, "A spectral model for RF oscillators with power-law phase noise," in IEEE Transactions on Circuits and Systems I: Regular Papers, vol. 53, no. 9, pp. 1989-1999, Sept. 2006, doi: 10.1109/TCSI.2006.881182.
[17] S.-L. Jang, Y.-J. Song, and C.-C. Liu, “A differential clapp-VCO in 0.13 CMOS technology,” IEEE Microw. Wireless Compon. Lett., vol. 19, no. 6, pp. 404–406, Jun. 2009.
[18] M. -D. Wei, S. -F. Chang, X. -W. Liu and G. -W. Ko, "Phase noise optimization of CMOS VCO with double-harmonic-tuned LC tank," The 40th European Microwave Conference, Paris, France, 2010, pp. 1054-1057, doi: 10.23919/EUMC.2010.5616601.
[19] H. Kim, S. Ryu, Y. Chung, J. Choi, and B. Kim, “A low phase-noise CMOS VCO with harmonic tuned LC tank,” IEEE Trans. Microw. Theory Techn., vol. 54, no. 7, pp. 2917–2923, Jul. 2006.
[20] Q. Liu, J. Sun, T. Yoshimasu, S. Kurachi, and N. Itoh, "15 GHz-band low phase-noise LC-VCO with second harmonic tunable filtering technique," 2009 IEEE 20th International Symposium on Personal, Indoor, and Mobile Radio Communications, Tokyo, Japan, 2009, pp. 1592-1595, doi: 10.1109/PIMRC.2009.5450190.
[21] M. Babaie and R. B. Staszewski, "A Class-F CMOS oscillator," IEEE J. Solid-State Circuits, vol. 48, no. 12, pp. 3120-3133, Dec. 2013, doi: 10.1109/JSSC.2013.2273823.
[22] M. Shahmohammadi, M. Babaie, and R. B. Statszewsi, “A 1/f noise upconversion reduction technique for voltage-biased RF CMOS oscillators,” IEEE J. Solid-State Circuits, vol. 51, no. 11, pp. 2610–2624, Nov. 2016.
[23] D. Murphy, H. Darabi and H. Wu, "Implicit common-mode resonance in LC oscillators," IEEE J. Solid-State Circuits, vol. 52, no. 3, pp. 812-821, March 2017, doi: 10.1109/JSSC.2016.2642207.
[24] Hai-Wen Liu, Xiao-Wei Sun and Zheng-Fan Li, "A VCO with harmonic suppressed and output power improved using defected ground structure," Proceedings of the 2003 SBMO/IEEE MTT-S International Microwave and Optoelectronics Conference - IMOC 2003. (Cat. No.03TH8678), Foz do Iguacu, Brazil, 2003, pp. 163-167 vol.1, doi: 10.1109/IMOC.2003.1244851.
[25] S. Saad, F. Haddad, and A. B. Hammadi, “Impact of multi-finger MOSFET geometry on the electrical performance of RF circuits,” Microelectron. Reliab., 129 (2022), Article 114445.
[26] S.-S. Song and H. Shin, "A new RF model for the accumulation-mode MOS varactor," IEEE MTT-S International Microwave Symposium Digest, 2003, Philadelphia, PA, USA, 2003, pp. 1023-1026 vol.2, doi: 10.1109/MWSYM.2003.1212543.
[27] R.-X. Yang, H.-C. Lee, S.-L. Jang " Low power CMOS VCO using an 8-shaped transformer," 2023 IEEE 23rd Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems (SiRF) 22 - 25 January 2023 Las Vegas, Nevada, USA.
[28] N. J. Oh, and S. G. Lee, “11-GHz CMOS differential VCO with back-gate transformer feedback,” IEEE Microw. Wireless Compon. Lett., vol. 15, no. 11, pp. 733–735, Dec. 2005.
[29] P. Wang et al., "A low phase-noise class-C VCO using a novel 8-shaped transformer," 2015 IEEE International Symposium on Circuits and Systems (ISCAS), Lisbon, 2015, pp. 886-889, doi: 10.1109/ISCAS.2015.7168776.
[30] J. Yang, C.-Y. Kim, D.-W. Kim and S. Hong, “Design of a 24-GHz CMOS VCO with an asymmetric-width transformer,” IEEE Trans. Circuits and Systems—II: Express Briefs, Vol. 57, No. 3, 2010, pp. 173-177.
[31] M.-D. Wei, S.-F. Chang, and S.-W. Huang, “An amplitude-balanced current-reused CMOS VCO using spontaneous transconductance match technique,” IEEE Microw. Wireless Compon. Lett., vol. 19, no. 6, pp. 395–397, Jun. 2009.
[32] R.-L. Wang, M.-C. Lin, Y.-J. Tzeng, C.-F. Yang and Y.-S. Lin, "A switched-capacitor current-reused VCO with symmetrical differential outputs," 2008 Asia-Pacific Microwave Conference, Hong Kong, China, 2008, pp. 1-4, doi: 10.1109/APMC.2008.4957869.
[33] A. Bhat, R. Nandwana and K. Lakshmikumar, "An interference suppression technique for millimeter-wave LC VCOs using a multiport coupled inductor," IEEE Trans. Circuits Syst. II: Express Briefs, vol. 69, no. 3, pp. 919-923, March 2022, doi: 10.1109/TCSII.2021.3134093.
[34] W. Deng et al., "An 8.2-to-21.5 GHz dual-core quad-mode orthogonal-coupled VCO with concurrently dual-output using parallel 8-shaped resonator," 2021 IEEE Custom Integrated Circuits Conference (CICC), Austin, TX, USA, 2021, pp. 1-2, doi: 10.1109/CICC51472.2021.9431447.
[35] Y. Peng, J. Yin, P. -I. Mak and R. P. Martins, "Low-phase-noise wideband mode-switching quad-core-coupled mm-wave VCO using a single-center-tapped switched inductor," IEEE J. Solid-State Circuits,, vol. 53, no. 11, pp. 3232-3242, Nov. 2018, doi: 10.1109/JSSC.2018.2867269.
[36] D. Murphy and H. Darabi, "2.5 A complementary VCO for IoE that achieves a 195dBc/Hz FOM and flicker noise corner of 200kHz," 2016 IEEE International Solid-State Circuits Conference (ISSCC), San Francisco, CA, USA, 2016, pp. 44-45, doi: 10.1109/ISSCC.2016.7417898.
[37] O. El-Aassar and G. M. Rebeiz, "A 350mV complementary 4-5 GHz VCO based on a 4-port transformer resonator with 195.8dBc/Hz peak FOM in 22nm FDSOI," 2019 IEEE Radio Frequency Integrated Circuits Symposium (RFIC), Boston, MA, USA, 2019, pp. 159-162, doi: 10.1109/RFIC.2019.8701844.
[38] A. Masnadi et al., “A compact dual-core 26.1-to-29.9 GHz coupled CMOS LC-VCO with implicit common-mode resonance and FoM of 191 dBc/Hz at 10 MHz,” in Proc. IEEE Custom Integr. Circuits Conf. (CICC), Mar. 2020, pp. 1–4.
[39] W. Jung, H. Kim, Y. Song, K. -H. Lee and D. -K. Jeong, "A 0.99μs FFT-based fast-locking, 0.82 GHz-to-4.1GHz DPLL-based input-jitter-filtering clock driver with wide-range mode-switching 8-shaped LC oscillator for DRAM interfaces," 2023 IEEE Custom Integrated Circuits Conference (CICC), San Antonio, TX, USA, 2023, pp. 1-2, doi: 10.1109/CICC57935.2023.10121322.
[40] Y.-J. Moon, Y.-S. Roh, C.-Y. Jeong, and C. Yoo, “A 4.39–5.26 GHz LC-tank CMOS voltage-controlled oscillator with small VCO-gain variation,” IEEE Microw. Wireless Compon. Lett., vol. 19, no. 8, pp. 524–526, Aug. 2009.