This is a VME card that may be used to receive and recover the RF
signal, bunch and revolution clocks over a White Rabbit network. Primarily, this card will function as a diagnostic card for the BE-RF group.
It will also be required to regenerate the bunch and turn clocks to drive the BST-Master and the
existing TTC system.
Whilst this board is targeting a specific application at CERN, this
design could be used to recover RF signals transmitted through an Ethernet network.
The card is designed to support a large range of frequency generation via some
The RF signal will be sourced directly from
the Low Level RF system through the transmission of Frequency Tuning Words (FTW).
The LLRF utilises a DDS to generate the required RF, enabling the FTWs to be
extracted and directly encoded into packets and then broadcast on a
White Rabbit network.
This VME card receives packets that contain FTWs and IQ setpoints from the
LLRF system. Then, using a FPGA with an assortment of analog components,
this design is able to recover the original RF signal.
This VME card can recover two RF channels, each comprising:
RF signal (up to ~400 MHz (see Nyquist limitations of the AD9912 1 GHz DDS).
Bunch or event Clock.
Turn or event Clock.
Contains monitoring options for the White Rabbit clocks:
10 MHz in/out SMA.
PPS in/out SMA.
White Rabbit clock.
General purpose LEMO connections:
4x GPIO LEMO.
External clock input.
External stop/sync input for Trigger Unit usage.
Dual SFP connectors with White Rabbit compliant interfaces.
Functional block diagram
FPGA, Connectivity and IO
Xilinx Kintex-7 FPGA XC7K160T-2FBG676C
Dual SFP connectors that are White Rabbit compliant.
External high performance 100 MHz OCXO oscillator, for White Rabbit 10
MHz clock clean-up.
Dual channel recovery of two RF clocks, specifically to support slip-stacking at two different frequencies.
Each RF channel requires:
DAC, LPF and Mixer pipeline. The LO frequency is sourced from the DDS at 223.5 MHz for both channels.
Front panel SMA: RF Out (0 dBm, 50 Ω).
Front panel SMA: Trigger 1 (1 V, 50 ns, 50 Ω). Supporting a bunch clock output.
Front panel SMA: Trigger 2 (1 V, 50 ns, 50 Ω). Supporting an orbit/revolution clock output.
Proposed Front Panel Layout
After development of the WR2RF-VME card to meet BE-RF's requirements for a diagnostic card. A second
development phase may be embarked upon to develop a BOBR replacemement card. More details on this
potential development may be found on the WR2RF-VME-BOBR page.