Design and Design and Fabrication of a Q-Fabrication of a Q-BPM Calibration Tone BPM Calibration Tone

Generator for the Generator for the ATF2ATF2

Ian BullockIan Bullock

August 14, 2008August 14, 2008

ATF2ATF2

Q-BPMsQ-BPMs

Cavity BPMs attached to quadrupole magnetsCavity BPMs attached to quadrupole magnets Give 6426 MHz signal downmixed to 20 MHzGive 6426 MHz signal downmixed to 20 MHz 20 MHz signal is then digitized and analyzed to 20 MHz signal is then digitized and analyzed to

determine beam position to better than 100 nmdetermine beam position to better than 100 nm

Need for a Calibration Need for a Calibration ToneTone

Downmix boards have variable gainDownmix boards have variable gain Gain must be calibrated to precisely Gain must be calibrated to precisely

determine electron bunch displacementdetermine electron bunch displacement

Calibration Tone DesignCalibration Tone Design

714 MHz input from master oscillator714 MHz input from master oscillator TTL logic input to control when output is onTTL logic input to control when output is on 6426 MHz output similar in frequency to signal 6426 MHz output similar in frequency to signal

obtained from a passing electron bunchobtained from a passing electron bunch

Calibration Tone Calibration Tone RequirementsRequirements

10 dBm 714 MHz input 10 dBm 714 MHz input 25 dBm 6426 MHz output25 dBm 6426 MHz output High switch isolation High switch isolation Low noise floorLow noise floor Spectrally pure outputSpectrally pure output

Calibration Tone Design Calibration Tone Design

SMA Connector DesignSMA Connector Design

RF SwitchRF Switch

FinalFinalBPFBPF

TriplerTripler

DoublerDoubler

SplitterSplitter

MixerMixer

AmpAmp

AmpAmp

HPFHPF LPFLPF 6426 6426 MHzMHzOutOut

714714MHzMHzInIn

TTL InTTL In

LPFLPF

SMA Design OutputSMA Design Output

SMA Switching SMA Switching PerformancePerformancePower Measured from Downmix Power Measured from Downmix Board at Board at

20 MHz20 MHz 40 MHz40 MHz 6426 MHz6426 MHz

Switch Switch on:on: 11 dBm11 dBm -43 dBm-43 dBm -81 dBm-81 dBm

Switch Switch off: off: -80 dBm-80 dBm -100 dBm-100 dBm -100 dBm-100 dBm

PCB DesignPCB Design

ConclusionsConclusions

6426 MHz output acceptable6426 MHz output acceptable Switch isolation also sufficientSwitch isolation also sufficient

PCB design still to be testedPCB design still to be tested Final amplifier neededFinal amplifier needed Installation in chassis requiredInstallation in chassis required

AcknowledgementsAcknowledgements

Doug McCormickDoug McCormick Steve Rock, Susan Schultz, Farah Steve Rock, Susan Schultz, Farah

RahbarRahbar SLAC, SULI, DOESLAC, SULI, DOE