Patterned ground shield for inductance fine-tuning
Document Type
Article
Publication Date
7-4-2022
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 mu m track spacing and a polysilicon PGS with finger spacing of 2.0 mu m. 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.
Keywords
Inductance tuning range, Inductor metal track spacing, On-chip spiral inductor, Patterned ground shield (PGS), PGS metal finger spacing, Q-factor
Divisions
sch_ecs
Funders
Collaborative Research in Engineering, Science and Technology (CREST) (Grant No: P16C1-17),Universiti Sains Malaysia,Universiti Malaya (Grant No: 304/PELECT/6050378/C121),Universiti Sains Malaysia Bridging Grant (Grant No: 304.PELECT.6316108)
Publication Title
IETE Journal of Research
Volume
68
Issue
4
Publisher
Taylor & Francis
Publisher Location
2-4 PARK SQUARE, MILTON PARK, ABINGDON OR14 4RN, OXON, ENGLAND