The rapid evolution of silicon semiconductor technologies, driven by the demands of 5G/6G communication systems, has opened new possibilities for their application in sub-millimeter-wave atmospheric observation instruments, particularly for radiometers deployed on nanosatellites. This thesis explores the potential of silicon-based front-end circuits operating at frequencies such as 183 GHz and 325 GHz, which are critical for characterizing hydrometeors and improving weather and climate models. Despite their promise, mainly based on cost and the potential of a co-integration of the front-end and the signal treatment on a single chip, silicon technologies face significant challenges at these frequencies, including lower electron mobility, higher substrate losses, compared to traditional III-V semiconductors. 

The integration of multiple high-frequency components—such as amplifiers, mixers, and filters—onto a single silicon chip presents both technical and design complexities, requiring advanced modeling and simulation techniques to mitigate parasitic effects and interconnect losses. Additionally, noise performance and power handling capabilities remain areas of concern, particularly for space-based applications where reliability and longevity are paramount. This research aims to address these limitations through innovative device design, material advancements, and optimization of fabrication processes to enhance the performance, scalability, and cost-effectiveness of silicon-based sub-millimeter-wave circuits. It should be noted that a first evaluation of the integration of a receiver architecture in an advanced 55 nm BiCMOS technology in the 325 GHz band was carried out in 2025 during a 6-month internship, as part of a collaboration between CNES, ST Microelectronics and LAAS-CNRS. 

This study showed that a conventional architecture using a LNA at the input of the front-end could remain a relevant solution, when this circuit adopted a cascode topology in addition with a transconductance boosting of transistors. However, the noise figure remains slightly above the specification, and a mixer-first receiver could be the best solution, especially when relying on a cold-MOS mixer used in sampling mode. LAAS-CNRS will be able to contribute with all its expertise in the design and the integration of this type of front-end at submillimeter waves. 

Following on from the work carried out during the 2025 internship, it will be suitable to explore in depth all possible solutions for the integration of the mixer which are making the most of BiCMOS technology. Once the mixer has been designed, the choice of the receiver topology will be made. This will include comparing the performance of the architecture integrating an LNA first followed by a mixer with that of a receiver composed of a mixer first followed by an LNA at the intermediate frequency (IF). As well, the interest of a two-step frequency conversion to go from the RF frequency in the 325 GHz channel to an IF frequency in the [0.4-12.2] GHz band will be evaluated. By implementing an initial conversion to a frequency band around 183 GHz followed by a direct conversion of this signal to the IF around 12.2 GHz, this solution could enable reception of the 325 GHz channel from a modular architecture reusing the local oscillator (LO), associated with properly sized frequency multipliers, as well as the receiver designed for the 183 GHz channel.

At this stage, all choices have been made, and the integration of the components alone, as well as the complete receiver, will be carried out in a BiCMOS technology from the French foundry STMicroelectronics. This work may be done for different options selected for the receiver.

Finally, the receiver will be characterized within the framework of LAAS-CNRS or within the framework of the RF-NET platform.

By leveraging the miniaturization and integration advantages of silicon technologies, this thesis work seeks to contribute to the development of next-generation radiometers capable of frequent and high-resolution atmospheric observations, ultimately improving weather forecasting and climate monitoring. The findings will provide insights into the feasibility of silicon as a viable alternative to III-V technologies for sub-millimeter-wave applications, paving the way for more accessible and sustainable nanosatellite constellations.

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For more Information about the topics and the co-financial partner (found by the lab!); contact Directeur de thèse - parra@laas.fr

Then, prepare a resume, a recent transcript and a reference letter from your M2 supervisor/ engineering school director and you will be ready to apply online  before March 13th, 2026 Midnight Paris time!