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.