Upload
shana-mccarthy
View
215
Download
0
Embed Size (px)
Citation preview
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‘
Frank Ludwig, DESY
Stability requirements on phase and amplitude of the vector sum of the cavity field vector :
Amplitude stability : 5105 A
Aδ
Phase stability : 01.0δφ
VμUδ EUROFEL 50(normalized to A=1V)
fSUδ U RMS-voltage noise of the detector :
- 50dB linearity of down-converters
- Low-noise design
- Reduce the measuring bandwidth
depending on LLRF-concept!
and linearity
δφ
Aδ
A
Stability requirements on phase and amplitude
- 43dB dynamic range of signal-to-noise
Requirements on the detectors linearity and noise:
Amplitude stability and linearity :
, /50 HznVSU MHzf 1
Without gain from vector sum
Frank Ludwig, DESY
Available technologies and selection of the detector concept
Passive Mixer + GaAs FET:
down up down down down down down down down down downLT5522 LT5521 LT5526 MC1502 CDB-9050 DBM-182 MBA-15L HMJ7 HMJ7-1 IAM-92516 AD8343
P(RF) dBm -7 -15 -10 -5 -10 -10 -10 -10 -12P(LO) dBm -5 -5 -5 7 -5 7 21 21 -3 -10P(IF) dBm -7NF dB 13,2 12,5 12,3 7,5 15 8,5 8,5 10,5 12,5 14,1IP3 dBm 25 24,2 16,5 12 -3 34 34 27 16,51dB dBm 10,8 11 5 0 23 23 9 2,8MS11 dBPS11 degMS22 dBPS22 degMS33 dBPS33 degGain dB -0,4 -0,5 0,5 6 6 -7,5 -6,5 -8,5 -8,5 -5,5 7,1RF to IF degisol IF RF dBiso LO RF dB 50 38 55 30 33 25 24 24 34iso LO IF dB 49 59 55 25 35 20 14 24 30 56 54IF(min) MHz 0,1 10 0,1 0 30 0 0 0 0
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
AD8343LT5522
Frank Ludwig, DESY
HznVSU /70]10,40[ dBmdBmPRF
+ High LO/RF isolation
- RF-range [DC-2.5GHz]
- Mixing into baseband
caused additional noise
Actual down-converter (AD8343+OPAmp) operating at 1.3GHz
dBmPLO 5linearitydB 70
8-channels from cavity probe : 8-channels to ADC-Board : LO-Input :
(Designed by G.Möller/DESY/MHF-p)
Frank Ludwig, DESY
Noise from sensor (down-converter-board) :
Noise characterization of the actual down-converter
MHzfUδUδ EUROFEL 1 ,2.1
MHzfUδUδ EUROFEL 10 ,0.4
RFP
IFP
dBP11db compression point
Noise floor High le
vel
mixe
r
Low le
vel
mixe
r
Noise problems
Crosstalk,isolation,leakageproblems
Linearity versus noise
linearitydBdBmdBmPRF 70 ],10,40[
2,, )( vSSS AMPUUU
HznV
S AMPU
/7,
HznV
SU
/70
MHzfLO 1300
MHzfRF 1300
5.8v
HznV
SU
/5.4
,
Frank Ludwig, DESY
Jitter conversion :
Tf
ft
IF
RF
fst 10
fsT 370
MHzf 1Measuring 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) LOf
1300(2997)
RFf
81=9 x 9IFf
DAC-clock
1300-81(2997-81)
Undersampling and Averaging
Proposed LLRF system for optimized detector operation
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
CircuitLNA
Evaluation
Board
AD6645
14 Bit, 80 MSPS,100fs jitter
BPF
BPF
1300 MHz(2997 MHz)
Stripline Filter
1291 MHz(2916 MHz)
Stripline Filter
Attenuator
LO-input
RF-input
Low-Noise-AmplifierLO Input
Matching
Circuit
Active Mixer
LT5522
(LT5527)
1300 MHz2997 MHz
1300-81 MHz(2997-81 MHz)
36 MHzUndersampling
36 MHz(from MO)
(from MO)
ADC clock
14
-5dBm
Manufactured in stripline design.
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.