Guest Editorial.

The IEEE Topical Meeting on Silicon Monolithic Integrated Circuits in RF Systems (SiRF) is a conference dedicated to the field of Si-based RF research, which encompasses the material, technology, devices, and more increasingly, circuits and systems, all based on Si for RF applications. Since its first meeting in 1998, it has continuously contributed to the popular adaption of Si technology to RF and millimeter-wave applications. After alternating between the US and Europe for the conference venues for the first five meetings, which were held every 1.5 years, SiRF has been annually held in the US since 2006 as part of IEEE Radio and Wireless Week. The 12th SiRF was held in Santa Clara, CA, January 16?18, 2012. One new attempt made for this year's conference was to encourage the authors of the presented papers to submit an expanded version to this TRANSACTIONS, which would be specially arranged for publication in a single issue if accepted. This was successfully implemented in this issue. Out of 56 papers presented at the conference, including both podium and poster papers, 12 papers were expanded and submitted. After the regular review process, five papers were finally accepted, a brief introduction of which is provided here. The Editor-in-Chief believes these selected papers will provide a more detailed description of the excellent results that were not available with the limited space allowed for the papers in the conference proceeding. [ABSTRACT FROM AUTHOR]