https://orcid.org/0000-0002-6198-263X
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ABSTRACT
Post-fabrication inductance variation is a big issue faced by chip designers of sensitive circuits, and on-chip tunable inductors seem to provide the solution to this problem. In addition, tunable inductors also benefit circuits that require the multi-frequency operation. This paper is on the design of a tunable inductor which utilizes the patterned ground shield (PGS) to enable fine-tuning capability. This work is unique as this is the first time that the PGS is used for this purpose, previous researches were more on the Q-factor merit provided by the inductors with PGS. In this work, inductor's and PGS parameters influencing the inductance tuning range and Q-factor performances were first determined. Subsequently, inductors with PGS made from different metals and track spacing were designed, with electronic circuitries implemented to control the grounding of each PGS metal finger. The hypothesis that the floating and grounding of each PGS metal finger can change the magnetic flux of the inductor which contributes to the inductance variation was verified using Sonnet EM. Measured results show that a 5.2% inductance tuning range and Q-factor of 5.9 were achieved at the Bluetooth frequency of 2.5 GHz for an inductor with 2.0 µm track spacing and a polysilicon PGS with finger spacing of 2.0 µm. The tunable inductor was further integrated into a power amplifier (PA) and simulation results show that it enables the PA to achieve the design specification at the frequency range of 3.3–3.8 GHz, dedicated for the sub-6 GHz 5G application.
ACKNOWLEDGEMENTS
The authors would like to thank SilTerra Sdn. Bhd. for the 0.11-µm and 0.18-µm CMOS model libraries and facilities provided for the inductor design, on-chip measurements and characterization. Special thanks and appreciation to USM for the fee support, facilities and services provided. Thank you to Universiti Malaya for the academic collaboration.
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Notes on contributors
Nur S. Yusof
Nur Syahadah Yusof received her BEng (Hons)(Electronic Engineering) from Universiti Sains Malaysia in 2017 and is currently working towards her MSc degree at the same institution. Her research interest is in on-chip passive device modeling. Email: [email protected]
Norlaili M. Noh
Norlaili Mohd Noh graduated with BEng electrical engineering (Honours) from Universiti Teknologi Malaysia and both MSc in electrical and electronic engineering and PhD in Integrated circuit design from Universiti Sains Malaysia. She is currently an associate professor with School of Electrical & Electronic Engineering, Universiti Sains Malaysia. Her specialization is in analog RFIC design.
Jagadheswaran Rajendran
Jagadheswaran Rajendran received his BEng degree (Hons) from Universiti Sains Malaysia in 2004, the MEng degree in Telecommunications from Malaysia Multimedia University in 2011, and the PhD degree in radio frequency integrated circuit (RFIC) design from the University of Malaya, in 2015. He is currently a senior lecturer at Collaborative Microelectronic Design Excellence Centre (CEDEC) and School of Electronic Engineering, Universiti Sains Malaysia. His research interest is RFIC design, analog IC design and RF system design for mobile wireless communications. Email: [email protected]
Asrulnizam A. Manaf
Asrulnizam Abd Manaf received the BEng and MEng in E&E from Toyohashi University of Technology, Japan in 2001 and 2005, respectively, and the PhD in Eng from Keio University Japan in 2009. He is an associate professor in USM since 2015. His current research interest includes development of microfluidic-based DNA sensor integrated with CMOS circuitry, micro fluidic based memristor, micro fluidic based tuneable inductor, micro fluidic thermoelectric generator (mTEG)-based energy harvesting, graphene-based transistor and micro 3-dimension fabrication technique by using grayscale technology. Email: [email protected]
Yusman M. Yusof
Yusman Mohd. Yusof received his BEng degree in electronic and computer engineering from Universiti Putra Malaysia (UPM) in 1999. He is currently a senior manager at Silterra (M) Sdn Bhd focusing on devices characterization and models development including the radio frequency (RF) and electrostatic discharge (ESD). Email: [email protected]
Harikrishnan Ramiah
Harikrishnan Ramiah is currently an associate professor at Department of Electrical Engineering, University of Malaya, working in the area of RFIC design. He received his BEng (Hons), MSc and PhD degrees in E&E engineering, in the field of analog and digital IC design from Universiti Sains Malaysia in 2000, 2003 and 2008 respectively. His main research interest includes analog IC design, RFIC design, VLSI system and RF energy harvesting power management module design. Email: [email protected]
Shukri K. K. Mohd
Shukri B Korakkottil Kunhi Mohd graduated with BEng (Hon) (Mechatronic Engineering) and MSc (Electronic) from Universiti Sains Malaysia (USM) in 2006 and 2011, respectively. He is working as a research officer at Collaborative Micro-Electronic Design Excellence Center (CEDEC), USM, where he is involved with test and measurement and analog IC design. Email: [email protected]
Mohamed F. P. Mohamed
Mohamed Fauzi Packeer Mohamed received the BEng in E&E from the Universiti Tenaga Nasional (UNITEN) Malaysia in 2002, the MSc degree in electronics system design engineering from the Universiti Sains Malaysia (USM) in 2010, and PhD degree in E&E from The University of Manchester (UoM) United Kingdom in 2015. His current research interests include analog and RF IC design; simulation, design, fabrication and characterization of high RF and high power devices based on compound semiconductor materials. Email: [email protected]