PROJECTS
An Ultra-Low Power, Miniaturized Transceiver for Autonomous Radio
Introduction
合作團隊: 成功大學郭泰豪教授、楊慶隆教授
本作品實現了一個使用綠能獵能器之能源自主無線收發機(EHTX & EXRX)，因應物聯網概念快速發展，無線感測節點必須具備低功耗、高效率、小體積之特性，透過自行開發之一顆壓電獵能晶片(Chip 1)、一顆發射機晶片(Chip 2)與一顆接收機晶片(Chip 3)為核心、太陽能電源管理晶片(Chip 4)，得以實現此一整合目標。
獵能系統之壓電獵能器晶片(Chip 1)採用新型瞬時突發式獵能技術，有別於傳統連續式獵能之方式，利用按壓遙控器之外力即產生自我供電的能量，在極短時間內有效獵取原按扣之瞬時能量供應後級低功耗發射機。不僅提升整體效率並同時縮減壓電片面積，避免廢棄電池造成的環境污染問題，符合綠色能源之永續發展目標。
無線發射機晶片(Chip 2)在架構上，透過注入鎖定與邊緣組合功率放大器實現倍頻功能，使得本地震盪源得以操作在低頻有效大幅降低功耗，也因而大幅減少所需之壓電陶瓷片面積，有效降低整體發射端體積，以符合整體產品微型化之需求。透過單次按壓遙控器按鈕，即可供電給發射機及微控制器，發射出射頻訊號。
無線接收機晶片(Chip 3)透過注入鎖定包絡直接偵測技術簡化系統架構，並可解調OOK/FSK/PSK 三種數位訊號，應用範圍相當廣泛。因接收機功耗遠低於光能獵能器之平均獵取能源，供電時接收機可永久開啟大幅減少系統延遲，保存絕大部分能源供應負載使用，一旦接收機收到通訊需求，便會驅動微控制器執行命令。
太陽能電源管理系統使用太陽能板、儲能元件與光獵能電源晶片(Chip 4)，採用快速獵取太陽板的最大功率且不受光照與溫度變化影響，故較傳統方法獵取更多能量。
本作品EHTX輸出功率達-12.9dBm，傳訊功耗僅750μW；EHRX靈敏度-80dBm，收訊功耗僅54μW。EHTX與EHRX操作於433MHz以平衡無線傳輸路徑損耗、天線尺寸增益與電路功耗，且能全向(360度)收發且不受遮蔽物影響，實測距離達8公尺。
Honors and Awards
1. 2015 科技部智慧電子國家型科技計劃 卓越計畫獎
2. 2016 科技部智慧電子國家型科技計劃 前瞻學術研究計畫特優獎
3. 2016第十六屆旺宏金矽獎–半導體設計與應用大賽 應用組優勝獎
4. 2016 TENG PRIZE科技創新創業獎 銅獎
5. 2017第十七屆旺宏金矽獎–半導體設計與應用大賽 設計組評審團銀獎
6. 鄭光偉、何文皓、張勝凱，應用於多通道頻率鍵移通訊的超低功耗發射機，中華民國專利第I535223號，2016年
7. K.-W. Cheng, W.-H. Ho, and S.-K. Chang, “Ultra Low Power Transmitter Applied in Multi-Channel Frequency Shift Keying (FSK) Communication,” US Patent 9,565,042, 2017.
8. S.-E. Chen, Chin-Lung Yang, and K.-W. Cheng, “A 4.5 μW 2.4 GHz Wake-Up Receiver Based on Complementary Current-Reuse RF Detector” in IEEE Int. Symp. on Circuits and Systems (ISCAS), May 2015, pp. 1214-1217.
9. S.-E. Chen and K.-W. Cheng, “A 433 MHz 54 μW OOK/FSK/PSK Compatible Wake-Up Receiver with 11 μW Low-Power Mode Based on Injection-Locked Oscillator” in IEEE European Solid-State Circuits Conference (ESSCIRC), Sep. 2016, pp. 137-140.
10. K.-W. Cheng and S.-E. Chen, “An Ultra-Low-Power Wake-Up Receiver Based on Direct Active RF Detection,” IEEE Trans. on Circuits and Systems I, vol. 64, no. 7, pp. 1661-1672, 2017.
Ultra-Low-Power Wake-Up Receiver for Self-Powering Sensor Platform
Introduction
隨著物聯網（Internet-of-Things，IoTs）的普及，人類生活周遭將大量佈置無線感測節點，這些節點需要能夠汲取周圍環境能量，實現自主操作的目標。在有限的功耗預算下，一個具備低功耗的喚醒接收機（Wake-Up Receiver，WuRx）用以監測通訊需求，僅在偵測到通訊需求時喚醒較耗能的主要收發機，有效降低通訊系統的功耗，並打破功耗與通訊延遲的權衡。為了實現超低功耗WuRx，傳統常採用開關鍵控（On-Off Keying，OOK）調變方案，具有電路架構簡單，能源效率高之優點，缺點則是易受雜訊干擾。相較之下，頻移鍵控（Frequency-Shift Keying，FSK）或是相移鍵控（Phase-Shift Keying，PSK）調變具有較佳之抗干擾能力，然而需求較複雜的解調器設計，提高系統設計難度，增加接收機功耗。本計畫以注入鎖定振盪器（ILO）與包絡檢測器（ED）實現接收機架構，可同時解調OOK/FSK/PSK三種訊號，有效簡化接收機架構，提高系統能源效率，並且可廣泛應用於許多物聯網之子領域。
Honors and Awards
1. S.-E. Chen, Chin-Lung Yang, and K.-W. Cheng, “A 4.5 μW 2.4 GHz Wake-Up Receiver Based on Complementary Current-Reuse RF Detector” in IEEE Int. Symp. on Circuits and Systems (ISCAS), May 2015, pp. 1214-1217.
2. S.-E. Chen and K.-W. Cheng, “A 433MHz 6.4μW FSK Receiver with -68dBm Sensitivity Based on Injection-locked Frequency-to-Amplitude Conversion”, in IEEE Int. Solid-State Circuits Conf. (ISSCC) - Student Research Preview(SRP), Feb. 2015.
3. S.-E. Chen and K.-W. Cheng, “A 433 MHz 54 μW OOK/FSK/PSK Compatible Wake-Up Receiver with 11 μW Low-Power Mode Based on Injection-Locked Oscillator” in IEEE European Solid-State Circuits Conference (ESSCIRC), Sep. 2016, pp. 137-140.
4. K.-W. Cheng, J.-S. Lin, and S.-E. Chen, “Reference-Less Ultra-Low-Power Wake-Up Receiver with Noise Suppression” in URSI Asia-Pacific Radio Science Conference, Aug. 2016, pp. 994-997. (Invited)
5. K.-W. Cheng and S.-E. Chen, “An Ultra-Low-Power Wake-Up Receiver Based on Direct Active RF Detection,” IEEE Trans. on Circuits and Systems I, vol. 64, no. 7, pp. 1661-1672, 2017.
Shih-En Chen
Low-Power RF Front End Design
Low Noise Amplifienabstract
A complementary current-reuse inductive source-degeneration common-source low noise amplifier (LNA) is presented for low-power and low noise-figure (NF) applications. A transformer-coupling technique is employed to improve the current efficiency and minimize the chip area. The LNA operates at 2.4 GHz and consumes 3 mW from a 1.2-V supply voltage, with a power gain of 13 dB, a NF of 1.8 dB, and an IIP3 of -8.9 dBm. A prototype device is designed and fabricated in 90-nm CMOS technology with a chip area of 1.0 × 0.75 mm2.
Quadrature Voltage-Controlled OscillatorabstractA trifilar-transformer-coupling quadrature voltage-controlled oscillator (TTC-QVCO) with dual transformer-feedback technology is proposed. Compared to traditional QVCOs, the proposed TTC-QVCO provides an additional coupling path, and therefore achieves an improved quadrature phase accuracy, a lower phase noise and a wider tuning range. The TTC-QVCO, implemented in a 0.18-μm CMOS technology, exhibits a frequency tuning range of 19.6% centered at 5.4 GHz and a power consumption of 5.4 mW from a 1.35 V supply voltage. The QVCO has a measured phase noise of -120.42 dBc/Hz at 1-MHz offset and quadrature phase error of less than 2° with a FoMT of 194.3 dB.
Honors and Awards
1. C.-M. Chou and K.-W. Cheng, “A Sub-2 dB Noise-Figure 2.4 GHz LNA Employing Complementary Current Reuse and Transformer Coupling” in IEEE International Symposium on Radio-Frequency Integration Technology (RFIT), Aug. 2016, pp. 1-3. (Final list of Best Student Paper Award)
2. K.-W. Cheng and Y.-R. Tseng, “5 GHz CMOS Quadrature VCO Using Trifilar-Transformer-Coupling Technology,” IEEE Microwave and Wireless Components Letters, vol. 26, no. 9, pp. 717-719, Sep. 2016.
3. 2017國家晶片系統設計中心 晶片製作 射頻電路組 特優設計獎
Government Research Projects
1. Co-Principal Investigator, “Analysis, design and implementation of high-security, low-power IoT circuits and systems,” Semiconductor Moonshot Project, Ministry of Science and Technology, Taiwan, May 2018–April 2022.
2. Principal Investigator, “Ultra-Low-Power Interferer-Resilient Wireless Transceiver for High RF Security Wake-Up IoT systems,” Semiconductor Moonshot Project, Ministry of Science and Technology, Taiwan, May 2018–April 2022.
3. Co-Principal Investigator, “The development of wireless lead-free piezoelectric MEMS accelerometers system with low power consumption”, National Applied Research Laboratories, Taiwan, Jun. 2017–Aug 2019.
4. Principal Investigator, “Ultra-low-power multi-mode wireless transceiver for IoT applications,” Ministry of Science & Technology, Taiwan, Aug. 2016–Jul. 2019.
5. Principal Investigator, “Low power quadrature voltage-controlled oscillator,” National Science Council, Taiwan, Aug. 2013–Jul. 2015.
6. Co-Principal Investigator, “A self-sustained wireless communication system with green energy harvesters,” National Program for Intelligent Electronics, Ministry of Science and Technology, Taiwan, May 2013–April 2016.
7. Principal Investigator, “An ultra-low power, miniaturized transceiver for autonomous radio,” National Program for Intelligent Electronics, Ministry of Science and Technology, Taiwan, May 2013–April 2016.
8. Principal Investigator, “Ultra low power wake-up receiver for wireless sensor networks”, National Science Council, Taiwan, Aug. 2012–Jul. 2013.
Industry Research Projects
1. Co-Principal Investigator, “AI and PUF-based Technologies for Low-power and Secure IoT Chips and Networks,” Qualcomm Technologies, Inc., San Diego, CA, US, Jun. 2020–May 2022.
2. Principal Investigator, “Design and Measurement of Radio Frequency Identification,” UltraChip, Taiwan, Jan. 2020–Jul. 2020.
3. Principal Investigator, “Wireless RF Energy Harvester,” CMOS-Crystal, Taiwan, Aug. 2018–Jul. 2019.
4. Principal Investigator, “Ultra-Low-Power Wake-Up Receiver for Self-Powering Sensor Platform,” Industrial Technology Research Institute, Taiwan, Dec. 2016–Dec 2017.
5. Principal Investigator, “Ultra Low Power Capacitive to Digital Converter for Environmental Humidity Detection on Self-Powering Sensor Platform,” Industrial Technology Research Institute, Taiwan, Dec. 2015–Dec 2016.
College Student Research Projects
1. Advisor, “A 30μW 2.4GHz LNA Utilizing Trifilar Transformer in 90nm CMOS Technology”, College Student Research Scholarship, Ministry of Science and Technology, Taiwan, Jul. 2020–Feb. 2021. (專題生: 楊登燊/蕭學謙)
2. Advisor, “Wi-Fi 無線獵能裝置”, Capstone Program, College of Electrical Engineering and Computer Science, National Cheng Kung University, Taiwan, March. 2016–Dec. 2016. (專題生:陳偉偉、蔡治廷、余欣翰、李暘、童耀新、陳國棨)
3. Advisor, “應用於腦波感知安全帽之神經放大器”, College Student Research Scholarship, Ministry of Science and Technology, Taiwan, Jul. 2015–Feb. 2016. (專題生: 張權安/李暘)
4. Advisor, “無線電獵能裝置轉換驅動電子鐘”, College Student Research Scholarship, Ministry of Science and Technology, Taiwan, Jul. 2014–Feb. 2015. (專題生: 陳偉偉/蔡治廷)
PUBLICATIONS
Journal Articles
1. S.-E. Chen, J.-S. Lin, H.-F. Li, and K.-W. Cheng, “A Reference-Less Wake-Up Receiver With Noise Suppression and Injection-Locked Clock Recovery”, in IET Circuits, Devices & Systems, vol. 14, no. 2, pp. 168-175, Mar. 2020.
2. K.-W. Cheng, S.-K. Chang, and Y.-C. Huang, “Low-Power and Low-Phase-Noise Gm-Enhanced Current-Reuse Differential Colpitts VCO”, IEEE Trans. on Circuits and Systems II: Express Briefs, vol. 66, no. 5, pp. 733-737, May 2019.(Invited)
3. K.-W. Cheng and S.-E. Chen, “An Ultra-Low-Power Wake-Up Receiver Based on Direct Active RF Detection,” IEEE Trans. on Circuits and Systems I, vol.64, no.7, pp. 1661-1672,July 2017.
4. K.-W. Cheng and Y.-R. Tseng, “5 GHz CMOS Quadrature VCO Using Trifilar-Transformer-Coupling Technology,” IEEE Microwave and Wireless Components Letters, vol. 26, no. 9, pp. 717-719, Sep. 2016.
5. X. Zou, L. Liu, J. H. Cheong, L. Yao, P. Li, M.-Y. Cheng, W. L. Goh, R. Rajkumar, G. S. Dawe, K.-W. Cheng, and M. Je, “A 100-Channel 1-mW Implantable Neural Recording IC,” IEEE Trans. on Circuits and Systems I, vol. 60, no. 10, pp. 2584-2596, Oct. 2013.
6. R.-F. Xue, K.-W. Cheng, and M. Je, “High-Efficiency Wireless Power Transfer for Biomedical Implants by Optimal Resonant Load Transformation,” IEEE Trans. on Circuits and Systems I, vol. 60, no. 4, pp. 867-874, Apr. 2013.
7. K.-W. Cheng and M. Je, “A Current-Switching and gm-Enhanced Colpitts Quadrature VCO,” IEEE Microwave and Wireless Components Letters, vol. 23, no. 3, pp. 143-145, 2013.
8. K.-W. Cheng, K. Natarajan, and D. J. Allstot, “A Current Reuse Quadrature GPS Receiver in 0.13µm CMOS,” IEEE J. Solid-State Circuits, vol.45, no.3, pp.510-523, Mar. 2010.
9. Y. Tang, K.-W. Cheng, S. Gupta, J. Paramesh, and D. J. Allstot, “Cascaded Complex ADCs with Adaptive Digital Calibration for I/Q Mismatch,” IEEE Trans. on Circuits and Systems I, vol.55, no.3, pp. 817-827, Apr. 2008.
Conference papers
1. S.-K. Chang, Z.-T. Tsai, and K.-W. Cheng, “A 250 kHz Resistive Frequency-Locked On-Chip Oscillator with 24.7 ppm/°C Temperature Stability and 2.73 ppm Long-Term Stability”, in IEEE Int. Symp. on Circuits and Systems (ISCAS), Oct. 2020.
2. Y.-T. Chiu , K.-W. Cheng, “ Quick Start-Up Crystal Oscillator Using Calibrated Injection Technique, ” in VLSI Design/CAD symp., Aug. 2020.
3. Y.-C. Huang, S.-K. Chang, and K.-W. Cheng, “A 2.4 GHz Gm-Boosted Complementary Current-Reuse Colpitts VCO with FoM of 189 dBc/Hz in 0.18 μm CMOS, ” in VLSI Design/CAD symp., Aug. 2019.
4. S.-K. Chang, S.-D. Yang, K.-W. Cheng, “A Direct FSK/QPSK Modulation Transmitter Employing Dual Injection Locking Techniques, ” in Taiwan and Japan Conference on Circuits and Systems, Aug. 2019.
5. Y.-C. Huang, S.-K. Chang, and K.-W. Cheng, “Low-Power and Low-Phase-Noise Gm-Enhanced Current-Reuse Differential Colpitts VCO”, in IEEE Int. Symp. on Circuits and Systems (ISCAS), May 2019, pp. 1-4.
6. W.-W. Chen, and K.-W. Cheng, “A UWB CMOS LNA with Current Reuse Negative Feedback, ” in VLSI Design/CAD symposium, Aug. 2018
7. W.-W. Chen, S.-D. Yang, and K.-W. Cheng, “A 1.2 V 490 μW Sub-GHz UWB CMOS LNA with Current Reuse Negative Feedback”, in IEEE Int. Symp. on Circuits and Systems (ISCAS), May 2018, pp. 1-4.
8. S.-K. Chang, K.-W. Chen, S.-D. Yang, C.-L. Yang, and K.-W. Cheng, “An Autonomous Wireless Transmitter with Piezoelectric Energy Harvester from Short-Duration Vibrations”, in IEEE Int. Symp. on Circuits and Systems (ISCAS), May 2018, pp. 1-4.
9. S.-K. Chang, and K.-W. Cheng, “A Low Power Gm-Enhanced Current-Reuse Differential Colpitts QVCO, ” in VLSI Design/CAD symposium, Aug. 2017
10. S.-E. Chen and K.-W. Cheng, “A 433 MHz 54 μW OOK/FSK/PSK Compatible Wake-Up Receiver with 11 μW Low-Power Mode Based on Injection-Locked Oscillator” in IEEE European Solid-State Circuits Conference (ESSCIRC), Sep. 2016, pp. 137-140.
11. C.-M. Chou and K.-W. Cheng, “A Sub-2 dB Noise-Figure 2.4 GHz LNA Employing Complementary Current Reuse and Transformer Coupling” in IEEE International Symposium on Radio-Frequency Integration Technology (RFIT), Aug. 2016, pp. 1-3. (Final list of Best Student Paper Award)
12. K.-W. Cheng, J.-S. Lin, and S.-E. Chen, “Reference-Less Ultra-Low-Power Wake-Up Receiver with Noise Suppression” in URSI Asia-Pacific Radio Science Conference, Aug. 2016, pp. 994-997. (Invited)
13. M. Je, J. H. Cheong, C. K. Ho, S. S. Y. Ng, R.-F. Xue, H.-K. Cha, X. Liu, W.-T. Park, L. S. Lim, C. He, K.-W. Cheng, X. Zou, Z. Chen, L. Yao, S. J. Cheng, P. Li, L. Liu, M.-Y. Cheng, Z. Duan, R. Rajkumar, Y. Zheng, W. L. Goh, Y. Guo, G. Dawe, “Wireless sensor microsystems for emerging biomedical applications” in IEEE International Symposium on Radio-Frequency Integration Technology (RFIT), Aug. 2015, pp. 139-141.
14. S.-E. Chen, Chin-Lung Yang, and K.-W. Cheng, “A 4.5 μW 2.4 GHz Wake-Up Receiver Based on Complementary Current-Reuse RF Detector” in IEEE Int. Symp. on Circuits and Systems (ISCAS), May 2015, pp. 1214-1217.
15. S.-E. Chen and K.-W. Cheng, “A 433MHz 6.4μW FSK Receiver with -68dBm Sensitivity Based on Injection-locked Frequency-to-Amplitude Conversion” in IEEE Int. Solid-State Circuits Conf. (ISSCC) - Student Research Preview(SRP), Feb. 2015.
16. J. Lee, V. V. Kulkarni, C. K. Ho, J. H. Cheong, P. Li, J. Zhou, W. Toh, X. Zhang, Y. Gao, K.-W. Cheng, X. Liu, M. Je, “A 60 Mb/s Wideband BCC Transceiver with 150 pJ/b RX and 31 pJ/b TX for Emerging Wearable Applications,” in IEEE Int. Solid-State Circuits Conf. (ISSCC) Dig. Tech. Papers, Feb. 2014, pp. 498-499.
17. X. Zhang, R. Xue, K.-W. Cheng, J. Cheong, C. Ho, L. Yao, C. He, and M. Je, “Design of High-Efficiency Inductive Power Transfer Coils for Biomedical Implants,” in IEEE MTT-S Int. Microwave Workshop Series on RF and Wireless Technologies for Biomedical and Healthcare Applications, Dec. 2013.
18. K.-W. Cheng,X. Liu, and M. Je, “A 2.4/5.8 GHz 10 µW Wake-Up Receiver With -65/-50 dBm Sensitivity Using Direct Active RF Detection,” in IEEE Asian Solid-State Circuits Conf. (ASSCC), Nov. 2012, pp. 337-340.
19. K.-W. Cheng, X. Zou, J. H. Cheong, R.-F. Xue, Z. Chen, L. Yao, H.-K. Cha, S. J. Cheng, P. Li, L. Liu, L. Andia, C. K. Ho, M.-Y. Cheng, Z. Duan, R. Ramamoorthy, Y. Zheng, W. L. Goh, Y. Guo, G Dawe, W.-T. Park, and M. Je, “100-Channel Wireless Neural Recording System with 54-Mb/s Data Link and 40%-Efficiency Power Link,” in IEEE Asian Solid-State Circuits Conf. (ASSCC), Nov. 2012, pp. 185-188.
20. M.-Y. Cheng, W.-T. Park, X. Zou, K.-W. Cheng, K. L. Tan, and M. Je, “A novel integration scheme for A low-profile 3d neuroprobe array microsystem,” in IEEE Asia-Pacific Conf. on Transducers and Micro/Nano Technologies, Jul. 2012.
21. A. T. Do, C. K. Lam, Y. S. Tan, K. S. Yeo, J. H. Cheong, X. Zou, L. Yao, K. W. Cheng, and M. Je, “A 160 nW 25 kS/s 9-bit SAR ADC for neural signal recording applications,” in IEEE 10th International New Circuits and Systems Conference (NEWCAS), Jun. 2012, pp. 525-528.
22. L. Andia, R.-F. Xue, K.-W. Cheng and M. Je, “Closed loop wireless power transmission for implantable medical devices,” in IEEE Int. Symp. on Integrated Circuits. (ISIC), Dec. 2011, pp. 404-407.
23. Z. Chen, K.-W. Cheng, Y. Zheng, and M. Je, “A 3.4-mW 54-Mbps Burst-Mode Injection-Locked FSK Transmitter,” in IEEE Asian Solid-State Circuits Conf. (ASSCC), Nov. 2011, pp. 289-292.
24. S. Gupta, Y. Tang, K.-W. Cheng, J. Paramesh, and D.J. Allstot, “Multi-rate polyphase DSP and LMS calibration schemes for oversampled data conversion systems,” in IEEE Intl. Conf. on Acoustics, Speech, and Signal Processing (ICASSP), May 2011, pp. 1585-1588.
25. K.-W. Chengand D. J. Allstot, “A Gate-Modulated CMOS LC Quadrature VCO,” in IEEE Radio Frequency Integrated Circuits (RFIC) Symp., Jun. 2009, pp. 267-270. (Best Student Paper Award)
26. N. M. Neihart, K.-W. Cheng, J. S. Walling, S. Yoo, and D. J. Allstot, “A 4-Antenna Transmitter in 0.18µm CMOS using Space-Time BlockCodes,” in IEEE Radio Frequency Integrated Circuits (RFIC) Symp., Jun. 2009, pp. 361-364.
27. K.-W. Cheng, K. Natarajan, and D. J. Allstot, “A 7.2mW Quadrature GPS Receiver in 0.13µm CMOS,” in IEEE Int. Solid-State Circuits Conf. (ISSCC) Dig. Tech. Papers, Feb. 2009, pp. 422-423.
28. H.-H. Chang, S.-P. Chen, K.-W. Cheng, and S.-I. Liu, “A 0.8V switched-opamp bandpass ΔΣ modulator using a two-path architecture,” in Proc. IEEE Asia-Pacific Conf. on ASIC, Aug. 2002, pp. 1-4.
Technical Report
鄭光偉、邱怡禎, “免電池物聯網連結的實現,” 科技部＜科學發展＞月刊, No. 527, 2016年11月.
Patents
1. 鄭光偉、吳奕慶、陳仕恩，自我補償互補式整流器，中華民國專利第I623182號，2018年。
2. K.-W. Cheng, W.-H. Ho, and S.-K. Chang, “Ultra Low Power Transmitter Applied in Multi-Channel Frequency Shift Keying (FSK) Communication,” US Patent 9,565,042, 2017.
3. 鄭光偉、何文皓、張勝凱，應用於多通道頻率鍵移通訊的超低功耗發射機，中華民國專利第I535223號，2016年。
4. K.-W. Cheng and M. Je, “Circuit Arrangement and Receiver Including the Circuit Arrangement”, US Patent 8,626,110, 2014 and Singapore Patent 188064, 2014.
5. K.-W. Cheng, Z. Chen, Y. Zheng, R.-F. Xue, and M. Je, “Receiver and Method of Controlling a Receiver,” US Patent App. 13/912,803, 2013.
6. K.-W. Cheng and M. Je, “Quadrature Voltage Controlled Oscillator,” US Patent App. 13/433,776, 2012.
7. Z. Chen, K.-W. Cheng, Y. Zheng, and M. Je, “Method and Apparatus for a Duty-Cycled Harmonic Injection Locked Oscillator,” US Patent 9231596, 2016 and Int. Patent App. WO2012134393, 2012.
