IPAC2011 - List of Authors (Schroeder, H.)

Paper	Title	Page
MOPC152	Digital Control System for Solid State Direct Drive™ RF-Linacs	436
	J. Sirtl, M. Back, T. Kluge Siemens AG, Erlangen, Germany H. Schröder ASTRUM IT GmbH, Erlangen, Germany
	The Solid State Direct Drive™ concept for RF linacs has previously been introduced. Due to the different methodology (i.e. solid state based rather than electron tube based) as compared with conventional RF sources a new control system is required to deliver the required LLRF. To support this new technology a fully digital control system for this new concept has been developed. Progresses in Digital – Analogue Converter technology and FPGA technology allows us to create a digital System which works in the 150 Mhz baseband. The complete functionality was implemented in a Virtex 6 FPGA. Dispensing with the PLL allows an excellent jitter-behaviour. For this job, we use three 12 bit ADCs with a Sampling Rate of 1 GS/s and two 16 bit DACs (1 GS/s). The amplitude of the RF source is controlled by dividing the RF modules mounted on the power combiner* into two groups and controlling the relative phase of each group (in effect mimicking an “out-phasing” amplifier). This allows the modules to be operated at their optimum working point and allows a linear amplitude behaviour. * O. Heid, T. Hughes, Proc. of IPAC10, THPD002, p. 4278, Kyoto, Japan (2010). ** O. Heid, T. Hughes, Proc. of LINAC10, THPD068, Tsukuba, Japan.

Paper

Title

Page

Digital Control System for Solid State Direct Drive™ RF-Linacs

436

J. Sirtl, M. Back, T. Kluge
Siemens AG, Erlangen, Germany
H. Schröder
ASTRUM IT GmbH, Erlangen, Germany

The Solid State Direct Drive™ concept for RF linacs has previously been introduced*. Due to the different methodology (i.e. solid state based rather than electron tube based) as compared with conventional RF sources a new control system is required to deliver the required LLRF. To support this new technology a fully digital control system for this new concept has been developed. Progresses in Digital – Analogue Converter technology and FPGA technology allows us to create a digital System which works in the 150 Mhz baseband. The complete functionality was implemented in a Virtex 6 FPGA. Dispensing with the PLL allows an excellent jitter-behaviour. For this job, we use three 12 bit ADCs with a Sampling Rate of 1 GS/s and two 16 bit DACs (1 GS/s). The amplitude of the RF source is controlled by dividing the RF modules mounted on the power combiner** into two groups and controlling the relative phase of each group (in effect mimicking an “out-phasing” amplifier). This allows the modules to be operated at their optimum working point and allows a linear amplitude behaviour.
* O. Heid, T. Hughes, Proc. of IPAC10, THPD002, p. 4278, Kyoto, Japan (2010).
** O. Heid, T. Hughes, Proc. of LINAC10, THPD068, Tsukuba, Japan.