RF Characterization and reliability of a power amplifier cell under large signal operation.

Politecnico di Torino RF Characterization and reliability of a power amplifier cell under large signal operation. Student: Javier A. Monguilo Mantovani ID: 263724 ABSTRACT The development of wireless communications is, perhaps, one of the most important technological advances humanity ever reached. Indeed, trying to imagine the contemporary World without any form of wireless network is almost impossible. From data transfer through smartphones that keep people connected, up to radars that keep air traffic safe close to airports, among many other applications, wireless systems play a significant role in modern life, guaranteeing not only commodity, but also safety. These advances have made humanity considerably dependent on the correct functioning of the wireless network infrastructure. Therefore, it is crucial to guarantee a reliable system of all the components present in the communication system. The power amplifier (PA) is a key component present in devices responsible for transmitting electromagnetic signals. This important element is in charge to deliver an electrical signal to the antenna with sufficient power so that, once converted into an electromagnetic wave, it can travel sufficiently far to reach a receiver within a certain distance. Thus, the PA is subject to high stress conditions in the transmission system which, consequently, make it prone to suffer aging degradation within its lifespan up to a point where it could no longer be able to function correctly and, consequently, to render the transmission system unusable. In order for newer technologies to be introduced to society, it is crucial to take into consideration the effects degradation will play on the system. For this reason, mathematical or SPICE models should be developed to bear in mind these decay effects during research and development. Failure of a PA realized in modern silicon technology can be attributed to 3 main phenomena affecting the transistor: breakdown (BD), hot-carrier injection (HCI) and Negative-bias temperature instability (NBTI). In this thesis, a set of new state-of-the-art silicon technologies designed by STMicroelectronics, built to be implemented as the PA present in a fifth generation (5G) transceiver, have been subjected to a reliability test. From high input powers up to high temperatures, these devices were tested under a wide variety of stress. Finally, models were developed to predict the degradation of these devices in an attempt to better characterize them. This work has been carried out as a part of an internship contract in the laboratory facilities of CEA-LETI, a prestigious entity located in Grenoble, France, that focuses on the research and applications of microelectronics and nanotechnology. Part of the characterization of the PA, as well of the objectives of the internship carried out, consisted of achieving 3 core objective: 1. Perform on-wafer characterizations, aging tests and analysis of PA cells under large signal operation and different stress conditions using a Load-Pull setup. 2. Transfer the current test sequence code to Python language for a more stable test bench. 3. Link the large signal stress results with DC stress coupled with S-parameters characterization in order to support the creation of a RF reliability model. These objectives could be achieved by the manipulation of sophisticated machinery used to stress the PAs, while concurrently working on the development of Python code, a general purpose progra