Digitally-Assisted RF Power Amplifier Design From CMOS Digital PAs to Adaptive Linearization: approaches to tackle complexity in RF Front-End development


JACOBS HALL (EBUI) BOOKER #2512, Jacobs School of Engineering, 9500 Gilman Dr, La Jolla, San Diego, California 92093

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In an ever more connected world, the proliferation of cellular bands and standards has caused a significant growth of the RF Front-End in a phone, which comprises the Power Amplifier (PA) and everything that is between the transceiver and the antennae. In this context, phone designers have put immense pressure on the shoulders of PA and front-end manufacturers, demanding condensation of more functions in smaller footprints, shorter design cycles, and shrinking cost.

In this talk, we argue that the most successful approach to sustain this ever-growing Front-End world will entail a mix of digital, analog, and RF approaches. We will claim that the most likely to succeed are those designers and those teams that can master a mix of techniques and system knowledge not traditionally associated with PA development.

We will start by reviewing the most fundamental PA design trade-offs and limitations, and some common misconceptions. We will discuss what happened to CMOS Power Amplifiers (did they ever make it to the same chip with the digital baseband?) and why.

Finally, we will describe a real-time adaptive digital predistortion system for power amplifier linearization, featuring fast closed-loop adaptation to provide robust linearity across quickly shifting PA operating conditions. We will show that discrete-time design techniques can be used to facilitate the development of a PA, by basically removing linearity from the design goals.

Speaker Bio:
CALOGERO D. “CAL” PRESTI received the Laurea degree in electronics engineering (cum laude) and the Ph.D. degree in electronics and automation engineering from the University of Catania, Italy, in 2005 and 2008, respectively. He also received the Diploma degree (cum laude) with major in Materials Science from the Scuola Superiore di Catania, Catania, Italy, in 2005.

From 2004 to 2005, he was with the Center for Materials and Technologies for Information and Communication Science (MATIS CNR INFM), Catania Italy, where he was involved in the modeling of nano-structured materials and the design of 2D photonic crystals for silicon based optoelectronics. In 2005, he joined the Radio Frequency Advanced Design Center (RF-ADC), Catania, Italy, a joint research group supported by the University of Catania and STMicroelectronics, where his Ph.D. research focused on CMOS Power Amplifiers, digital PAs, RF switches, device reliability, and PA linearization. During 2009, he was a Postdoctoral Researcher at the University of California, San Diego, where he mainly worked on PA digital predistortion, and co-designed various RF PAs and analog circuits for PA envelope tracking. In 2010, he joined Qualcomm, San Diego, CA, where he is currently part of the RF Front-End design team, and where he specializes in the design of CMOS- and GaAs-based power amplifiers, RF switchable passive networks, front-end modules, and related system-level optimization techniques.

Dr. Presti co-authored more than 40 papers in international journals and conferences, and 14 US patents.