Advanced Photon Source RF Beam Position Monitor Upgrade Robert M. Lill
Filter Comparator (original design) to ATT LPF A+B ATT BPF S bo ATT ATT LPF 180 A-B 180 ATT BPF D x ti ATT LPF C+D ATT BPF D y 180 180 to ATT LPF C-D DIV Test /Timing
Monopulse Receiver Dy Te st Dx Switch 90 deg LIM S+ j D Te st Hybrid X LP F A D/S S 0/1 80 LIM j S+D Te st LOG A S Control
Signal Conditioning and Digitizing Unit Sele ct D/S A Gated Integ. D/S A/D S A Peak Det. Gate Convert S A/D Latch To FIFO Memory Convert Gate Buttons Trig. Rec. Mode TIMING ARM To Rec.
RFBPM Upgrade Design Objectives Reduce Insertion Loss of Receiver Front- End Reduce Reflected Power Between Receiver and Buttons Electrodes Reduce Time domain Band-Pass Filter Side Lobes Improve System Maintainability
Filter-Comparator Upgrade to Z/LP BPF A+B S bo Z/LP BPF 180 A-B 180 Dx ti Z/LP BPF 180 C+D 180 D y to Z/LP BPF C-D TEST COUPLER PHASE ADJUST
Phase I Matching Network Matches the output of the button electrode to 50 ohms and eliminates the need to place 6 db attenuators on the output of the button electrodes. Facilitates moving the band pass filter and comparator out of the tunnel. Band limits (100 MHz) the output of the button electrodes. Increases button output by 8 db
Matching Network Development ESRF narrow band (8 MHz 3 db BW) 16.5 db signal improvement PTI (50 MHz 3 db BW) with 15 db signal improvement Angle Linear broad band (100 MHz 3 db BW) with 8 db improvement includes LPF
ESRF Matching Network 8 MHz BW I beam 5pf 2 pf 37 nf
Matching Network 50 MHz BW 1 I beam 5pf 2 pf 30 nf
Matching Network 100 MHz BW with lowpass filter 1 2 1 2 9 31 nf 13 nf I beam 5pf 20 pf 10 pf
100 MHz BW matching network with lowpass filter as built
Button Electrode Matching Network Implementation
Capacitive Button Electrodes Button electrode reflects 97 % power on feed through side Requires attenuators close to output to minimize reflections
Capacitive Button Electrodes with Matching Network Button/matching network measure greater than 30 db return loss 13 dbm (20 mw) button output power in a 100 MHz bandwidth
Matching network output with 6 bunches @ 1.67 ma/bunch
Phase II Upgrade Bandpass Filter and Monopulse Comparator Increases signal strength by removing matching attenuators and by using low loss components Improves return loss Improves bandpass time domain side lobe rejection
Bandpass Filter Development Coaxial cavity resonator Transversal coaxial delay line Transversal stripline serpentine design Transversal surface acoustic wave (SAW)
Transversal Bandpass Filter t1+trf*3 t1+trf*2 t1+trf*1 Delay t1 8 way splitter 8 way splitter t1+trf*4 t1+trf*5 t1+trf*6 t1+trf*7
Surface Acoustic Wave (SAW) Bandpass Filter
Cavity filters with 6 bunches @ 1.67 ma/bunch sum input
16 pulse transversal filters with 6 bunches
Receiver output with Cavity bandpass with 6 bunches @ 1.67 ma/bunch
Receiver output with Lorch bandpass filter
Lorch bandpass filter response
Receiver output with 16 MHz Cavity bandpass filter
Receiver output with16 pulse transversal bandpass filter
Monopulse Comparator Specification
Maintainability Test couplers provide access to input signals during operation Test couplers provide injection points for self test Access to the tunnel to calibrate and repair are minimized Future improvements to add sector calibration module can be realized
Major Design Differences Matches the button impedance vs. attenuating reflected standing waves Moves comparator and band pass filter out of the accelerator tunnel Different comparator and band pass filter topologies
R&D PLAN Obtain 4 SAW filter prototypes as soon as possible Obtain 4 serpentine transversal filter laid out on low cost substrate as soon as possible Obtain 9 component rat race hybrid networks (connectorized) by CY98 Obtain 36 bandpass filters of choice (connectorized) by CY98
Cost Phase I cost $150,000 Phase II comparator estimated cost $250,000