Advance Silicon Micromachined Passive Components for High-performance Millimetre and Sub-millimetre wave Systems
Time: Fri 2024-09-20 09.00
Location: F3 (Flodis), Lindstedtsvägen 26 & 28, Stockholm
Language: English
Subject area: Electrical Engineering
Doctoral student: Mohammad Mehrabi Gohari , Mikro- och nanosystemteknik, THz Group
Opponent: Professor Vicente Boria, Universitat Politècnica de València, València, Spain
Supervisor: Professor Joachim Oberhammer, Mikro- och nanosystemteknik; Oleksandr Glubokov, Mikro- och nanosystemteknik
QC 20240819
Abstract
This thesis investigates advanced silicon micromachined passive component design solutions for high-performance millimetre and sub-millimetre-wave systems, representing the state-of-the-art in modern microwave and RF systems. The proposed designs are fabricated through deep reactive ion etching (DRIE). Silicon micromachining using DRIE offers the ability to fabricate small feature sizes, making it ideal for millimetre and submillimeter-wave systems applications, with low surface roughness and manufacturing tolerances in a scalable process. The proposed design solutions utilize waveguide-based technologies with the goal of advancing future generations of satellite communications, radar, remote sensing, and biomedical instrumentation.
The core of this work is to propose design solutions to overcome manufacturing limitations, reduce transmission losses, introduce new design methods to enhance component performance, and simplify overall design complexity.
The first part of the thesis introduces new platforms for transferring electromagnetic waves within silicon micromachined chips. Two structures are presented: a silicon-micromachined E-plane waveguide bend for flange-to-chip connection and a broadband on-chip rectangular waveguide 90º twist both for 220-325 GHz. The E-plane bend is crucial for transferring waves from outside the chip to the inside and eliminating reliance on external fixtures. The on-chip silicon micromachined twist enables interconnection of H-plane and E-plane waveguide subsystems, that increases fabrication flexibility.
The second part discusses several novel filter design solutions operating at different frequency ranges from 90 to 300 GHz, each exhibiting state-of-the-art performance. An ultra-narrowband 4thorder filter with a wide spurious-free rejection band is developed for183 GHz. This filter utilizes high-Q-factor TM330 mode resonators and exhibits a measured Q-factor of 1000, surpassing any previously reported values in this frequency range. Additionally, a new negative coupling structure suitable for rectangular waveguide filters is proposed, offering compatibility with various fabrication methods, such as CNC milling and silicon micromachining. Using this negative coupling, a 4th-order quasi-elliptic bandpass filter with a centre frequency of 270 GHz and a fractional bandwidth of 2.2%is developed. Furthermore, a frequency variant coupling structure designed for rectangular cavities is proposed, enabling in-line filters with N+1 transmission zeroes, which can be easily manufactured and integrated with other subsystems. Using the proposed coupling structure, two filters are developed at 270 GHz: one 4th-order with 3transmission zeroes (TZs) and one 2nd-order with 3 TZs. Moreover, an integrated eighth-degree lowpass waveguide filter having a cut-off frequency of 280 GHz is presented. The lowpass filter is also fabricated using DRIE, with the aid of the twist proposed in section one. Furthermore, a compact band-pass filter with triplet response using one triangular singlet and two iris resonators is developed. Finally, a filtenna is introduced, combining a 4th-order filter with two slot antennas. The utilized filter employs 4 rectangular singlets introducing 4 transmission zeroes. The measured gain of the structure is 7 dBi, considering the use of on-chip E-plane bend transition to enable a direct connection to the flange.