The aim of the present paper is to show that new generations of RF amplifiers do exist with different technologies.
Thales has a very long experience in gridded tubes and klystrons for science and broadcast applications as well as solid state solutions for broadcast applications. This experience in both technologies has been applied to RF amplifiers in order to take benefit of these different technologies for high power requirements
Vacuum electron devices and solid state technologies should not be taken as two opposite options, or the old and the new ones, or the low and high power ones but as two technologies that have to be considered together to derive the best solutions for a defined requirement.
As far as gridded tubes are concerned, the main evolution in that technology has been the Diacrode concept. In order to avoid the power limitation of conventional gridded tubes due to RF losses, Diacrodes do use folded grids. This option has been proven for TV broadcast over the years and for some specific science and industrial applications.
The knowledge of both klystron and gridded tube technologies has allowed to derive the Inductive Output Tubes (IOT). After being extensively used for TV broadcast (in a pulse mode, in a certain sense), it has been installed in cw operation scientific systems for years now. The need for distributed sources in synchrotrons has increased the number of possible IOT installations (Elettra, Diamond, Boomerang or Alba). Examples at 500 MHz, 800 MHz and 1300 MHz are presented.
Solid State Device (SSD) solutions do present some very interesting features but also some drawbacks that need to be taken into account, especially for systems that will operate for several decades. SSD are based on the use of single transistors: their single power capability is the prime parameter to derive high power amplifiers. Evolutions of SSD will be shown.
These different technologies, gridded tube, Diacrode, klystron, IOT and SSD should be considered as building blocks that can be combined in order to fulfill a defined need. Examples of such combinations are shown and discussed.