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RPC Front End Electronics

RPC Front End Electronics. On chamber discriminator The strips The CMS discriminator chips The discriminator board Test results The TDC board The TDC and Crate block diagram The TDC board test result The trigger board The board counts Status. RPC Strip.

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RPC Front End Electronics

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  1. RPC Front End Electronics • On chamber discriminator • The strips • The CMS discriminator chips • The discriminator board • Test results • The TDC board • The TDC and Crate block diagram • The TDC board test result • The trigger board • The board counts • Status PHENIX RPC review C.Y. Chi

  2. RPC Strip • Our chamber is closely follow the CMS design. Our on-chamber electronics will try to follow their electronics too. • The CMS barrel strips is 1.3m long, 4 cm or 2cm wide. • 15/40 ohms impedance. 420pf/160pf capacitance. • Fully terminated strips. • CMS endcap RPC • Cover 5/16 degree in phi, 7 to 38mm in width and 22 to 55 cm in length • Un-terminated. • Lemo cables are used to connect strip to the discriminator board • PHENIX RPC strip width range from 11.4 mm by 141mm to 64.6 mm by 554.2mm. • The smallest one has 46 ohms impedance and 16 pf of capacitance. • The largest one has 10 ohms impedance and 286 pf of capacitance. PHENIX RPC review C.Y. Chi

  3. CMS RPC preamp/discriminator chip Build on AMS 0.8 um BiCMOS process, +5V device. 15 ohms input impendence. 45mW/channel. 8 channels per chip. It is designed in Bari, Italy. It has preamp, gain stage, zero crossing discriminator, monostable (cover the dead time) and LVDS driver. The chip is designed to deal with 20 fC up to 20 pC with1.7fC ENC noise. Zero crossing is necessary to deal with large dynamic range. The time walk is about .6ns except for very large charge. Testing show that threshold level could be as high as 100fc without loosing efficiency. All the chips has been fabricated. Two wafers has been packaged and tested. PHENIX RPC review C.Y. Chi

  4. RPC 32 channel discriminator board Cable adapter board LVDS discriminator output Serial download 32 channels per board Fused +6V input analog/digital power supply ~.46A (use +5V, +3V through low drop regulators) Serial download is used to set 10 bits 4 channel threshold DAC (4mv per bin) and Fire test pulse. PHENIX RPC review C.Y. Chi

  5. Connection diagram Half octant Module edge 3M (Gray) 3432-5302 RPC TDC 64 ch RPC disc 32 ch 3M (Gray) 3417-6640 Adapter Board 16 short RG174 cables 2-3 m cable ? 8 meters cable ? 3M N3432-L302RB 3M 6834-4500PL Or 8534-4500pl 3M 4640-7300 3M (gray) 3431-5302 2-3 m cable? 8 meter cable ? Adapter Board 3M (Black) D89140-???? 3M (Black) 3432-5302RB Signal Cable : 40 conductors twist flat ribbon cable 3M 1700/40 Twisted Pair, Flat Cable, .050" 28 AWG Stranded Fire rating VW-1 PHENIX RPC review C.Y. Chi

  6. On board test pulse vs. threshold study The discriminator is moving 4mv per step. The test pulse is feed to the input amplify through 1pf cap. (not for calibration, functional check only) Channel 14 TDC distribution, DAC step =80 TDC step PHENIX RPC review C.Y. Chi

  7. Direct pulse injection (threshold effect) CMS Disc threshold Channel 26 Channel 26 Channel 28 TDC Channel 30 Channel 32 Channel 32 Threshold (8 mv per step) TDC distribution at step =20 (160mv) Test pulse is set around ~ 4mv input PHENIX RPC review C.Y. Chi

  8. Direct Pulse Injection (fixed threshold) Channel 44 Channel 45 Channel 46 TDC disc. fired Input (steps) Inject test pulse through the cable adapter card + 10pf capacitance (channel 45) 2mv per step, 160mv threshold (~80fc) Cross talk seen at round 100mv. PHENIX RPC review C.Y. Chi

  9. DISC LVDS output at discriminator board 1.4V DISC output after ~10 meter cables 1.63V 69 ns time difference 1.61ns/ft  ~42 ft Digitally subtracted pulse between + and – side of discriminator LVDS output 500mv per division Long output cable study PHENIX RPC review C.Y. Chi

  10. RPC TDC MODULE Interface Chip Collects 64 Channel Of Data L1 trigger primitives TDC serial download Trigger window L1 trigger primitives Event Data 32 channel digitizer D I S C Disc Serial download LVDS Transmitter MASK Digitized Data LVDS Receiver Serial Download Timing etc. L1 trigger etc Event Data 44X BC Test Pulse Serial download PLL Test Pulse 44X BC 4x beam clock PHENIX RPC review C.Y. Chi

  11. TDC Module TDC: Use 44X beam crossing clock to digitized the discriminated LVDS pulse, ~2.5ns for 9.6MHz RHIC clock Test Pulse: Generated internally with the FPGA with the same 44x beam crossing clock Trigger Window: The lower and upper limits be can set channel by channel Mask: Mask bits can be set to turn off individual channel. Serial data to Discriminator Board: Control test pulse firing and discriminator threshold ( chip by chip) The TDC Internal Test Pulse Scan average TDC value Sigma on the TDC test pulse step test pulse step PHENIX RPC review C.Y. Chi

  12. RPC FEM crate L1 primitives XMIT T D C T D C Output To L1 Clock fanout Clock Master TDCs Slow Control GTM DCM L1 RPC(HBD) crate/BUS structure 6Ux160 mm VME size PHENIX RPC review C.Y. Chi

  13. RPC Trigger Board Transceiver blocks Arria FPGA De-serialized FEM data & format trigger data Optical transmitter 2.8 Gbits/sec Optical transmitter Trigger data from FEM 1 pair of cable per FEM RPC triggers is being designed. Schedule for prototype around Sept. The module can receive up to 6FEM’s trigger data The optical trigger data contains, idle, clock numbers and up to 12 16bits FEM trigger data every beam crossing. PHENIX RPC review C.Y. Chi

  14. Channel count etc… (one side) The crate size is like 6U VME crate. I would like to limit the length discriminator cable to 10 meters. (to be tested about jitters) The RPC2, 3, we will need to find the crate space near the detector. Crate need to be recess in the rack. Cable routing space needed in front of the crate.

  15. Channel count etc with RPC2/3 strips combined… (one side) The crate size is like 6U VME crate. I would like to limit the length discriminator cable to 10 meters. (to be tested about jitters) The RPC2, 3, we will need to find the crate space near the detector. Crate need to be recess in the rack. Cable routing space needed in front of the crate.

  16. STATUS • The discriminator and TDC modules has been successfully prototyped. • Waiting for on chamber testing. • Grounding issue need to be resolved with chamber testing • CMS 32 channel board has been tested in both Colorado and BNL factory. • We are building, 40 discriminator modules, 20 TDC boards, 3 sets of crates+ clock master modules for the coming run and individual factory readout/test stand. • Trigger modules is being designed. PHENIX RPC review C.Y. Chi

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