1. Frank Ludwig, DESY Content : 1 Stability requirements on phase and amplitude 2 Available technologies and selection of the detector concept 3 Proposed LLRF system for optimized detector operation 4 Status of the multi-channel EUROFEL LLRF-detectors 5 Future work and open questions EUROFEL DS3-DS4 Task Meeting, 17/05/05 Frank Ludwig, DESY ‚Multi-channel RF Amplitude and Phase Detector‘

2. Frank Ludwig, DESY Stability requirements on phase and amplitude of the vector sum of the cavity field vector : Amplitude stability : Phase stability : (normalized to A=1V) RMS-voltage noise of the detector : - 50dB linearity of down-converters - Low-noise design - Reduce the measuring bandwidth depending on LLRF-concept! and linearity Stability requirements on phase and amplitude - 43dB dynamic range of signal-to-noise Requirements on the detectors linearity and noise: Amplitude stability and linearity : Without gain from vector sum

3. Frank Ludwig, DESY Available technologies and selection of the detector concept Passive Mixer + GaAs FET: Active Mixer (Gibert cell): + High linearity + Low NF - Large LO drive needed - Low LO/RF isolation + High conversion gain + Low LO drive needed + High LO/RF isolation - Normal NF - Additional 1/f-noise Other detectors : HMC439: phase detector SiGe + Low NF, - Limited to 1.3GHz AD8347 : quadrature demodulator - to be tested in ‚parallel‘ AD8302 : gain, phase monitor + good temperature stability - worse NF Multi-channel detector : Gilbert cell mixer AD8343 LT5522

4. Frank Ludwig, DESY + High LO/RF isolation - RF-range [DC-2.5GHz] - Mixing into baseband caused additional noise Actual down-converter (AD8343+OPAmp) operating at 1.3GHz 8-channels from cavity probe : 8-channels to ADC-Board : LO-Input : (Designed by G.Möller/DESY/MHF-p)

5. Frank Ludwig, DESY Noise from sensor (down-converter-board) : Noise characterization of the actual down-converter 1db compression point Noise floor High level mixer Low level mixer Noise problems Crosstalk, isolation, leakage problems Linearity versus noise

6. Frank Ludwig, DESY Jitter conversion : Measuring bandwidth : Precise synchronization of ADC-clocks and clock jitter must average. Measuring bandwidth can be minimized (Noise reduction by a factor of 3...5). + - Filtering of higher harmonics and distortions. + No noise from LO-driver. + Proposed LLRF control system operating with a CW LO-signal : FPGA Master-Oscillator klystron high-power cavity down-converter LO-input RF-input ADC-clock 1300-81 (2997-81) 1300 (2997) 81=9 x 9 DAC-clock 1300-81 (2997-81) Undersampling and Averaging Proposed LLRF system for optimized detector operation

7. Frank Ludwig, DESY Status of the multi-channel EUROFEL LLRF detectors Structure of single down-converter (discrete prototype) : IF Output Matching Circuit BPF 81MHz SMD-Filter Input Matching Circuit Output Matching Circuit LNA Evaluation Board AD6645 14 Bit, 80 MSPS, 100fs jitter BPF 1300 MHz (2997 MHz) Stripline Filter 1291 MHz (2916 MHz) Stripline Filter Attenuator LO-input RF-input Low-Noise-Amplifier LO Input Matching Circuit Active Mixer LT5522 (LT5527) 1300 MHz 2997 MHz 1300-81 MHz (2997-81 MHz) 36 MHz Undersampling 36 MHz (from MO) ADC clock 14 -5dBm Manufactured in stripline design.

8. Frank Ludwig, DESY Future work Next steps : - Measure performance of the disrete single channel down-converter prototype at 1.3GHz with existing Master-Oscillator at DESY. - Performance evalution in the accelerator environment. - Redimension RF-filters to 3GHz and build a single channel detector on one board. - Design multi-channel board. - Optimize shielding and minimize channel crosstalk. - Integrate FPGA (data preprocessing), Gigalink or Fiberlink onto the board. Check alternatives to overcome the mixers noise limitation : - Passive mixer + RF-Transformer + LNA - interferometric techniques - Seperate farm of phase and amplitude detectors (Hittite, Analog Devices, Linear Tech.) - Integrated farm of Gilbert cell mixers. - Chipdesign using InP-HEMTs (promise higer gain and lower noise). Questions to be answered : - Noise performance of LLRF system including the Master-Oscillator achitecture. - Determine residual jitter of the LLRF concepts.