Public defence in Micro- and Nanoelectronic Circuit Design, M.Sc. Md Najmussadat

The title of the thesis: Design and characterization of integrated millimeter-wave radio front-end circuits for high-speed wireless communication and radiometric receivers 

Thesis defender: Md Najmussadat
Opponent: Prof. Timo Rahkonen, University of Oulu, Finland
Custos: Prof. Kari Halonen, Aalto University School of Electrical Engineering

This doctoral thesis investigates the design and characterization of integrated millimeter-wave front-end circuits in 130 nm SiGe BiCMOS technology. The research targets wireless communication and radiometric receiver applications in the 200–300 GHz range. 

The purpose of the study was to demonstrate that silicon-based MMICs can meet the stringent performance requirements of sub-terahertz systems while offering compactness, scalability, and lower cost compared to compound semiconductor solutions. 

The work is highly relevant to research on 6G communication, phased arrays, and radiometric imaging, where the demand for high-gain, efficient, and integrable circuits is critical. 

Key results include: 

1. An E-band Doherty power amplifier with improved efficiency at back-off,
2. A 240 GHz seven-stage low-noise amplifier achieving 28 dB gain,
3. A four-way power-combined amplifier with state-of-the-art performance near 250 GHz,
4. A 220–240 GHz phase shifter chain with 18 dB gain and 360° tuning, and
5. A 240 GHz radiometric receiver front-end integrating an antenna, amplifiers, mixer, and detector. 

The main conclusion is that SiGe BiCMOS is a viable platform for sub-THz front-end integration, enabling circuits that rival III–V technologies in performance. The research provides new design methodologies and experimental demonstrations that advance the state-of-the-art in silicon-based mm-wave electronics.

Key words: Millimeter-wave, MMIC, LNA, PA, Radiometric receiver

Thesis available for public display 10 days prior to the defence at Aaltodoc.