Sept 25, 2008 PHENIX RPC review C.Y. Chi 1 RPC Front End Electronics On chamber discriminator The strips The CMS discriminator chips The discriminator.
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Sept 25, 2008 PHENIX RPC review C.Y. Chi 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
Sept 25, 2008 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 encap 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.
Sept 25, 2008 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.
Sept 25, 2008 PHENIX RPC review C.Y. Chi 4 Chip production With help of Giuseppe Isaelli and Flavio Loddo from Bari Italy, we got 4 32 channel CMS boards about 1.5 years ago. These boards works both on the bench in Nevis and chamber testing in University of Colorado. We decide to use the CMS RPC chip as the frontend discriminator chips. With help of Flavio, the chip production start at end of the last year. The wafer is fabricated in AMS through EuroPratice and packaged in Taiwan The chip testing is done by Matrix. (the same company did the CMS RPC chip testing) The yield is around 99%, few bad chips out of ~2000 We now have twice more chips than we needed in hand.
Sept 25, 2008 PHENIX RPC review C.Y. Chi 5 Cable adapter board RPC 32 channel discriminator board 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. One DAC setting per chip. LVDS discriminator output Serial download The design is following closely the CMS design
Sept 25, 2008 PHENIX RPC review C.Y. Chi 7 The discriminator’s threshold 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 On board test pulse vs. threshold study TDC bin size ~2.5ns Range from 0 to 43
Sept 25, 2008 PHENIX RPC review C.Y. Chi 8 Direct Pulse Injection (fixed threshold) & Cross Talk Study Inject test pulse through the cable adapter card + 10pf capacitance (channel 45) 2mv per step, 160mv threshold (~80fc) Cross talk seen at round 100mv on channel 46. Input (steps) Channel 45 TDC Channel 46Channel 44 disc. fired No disc fired No disc fired
Sept 25, 2008 PHENIX RPC review C.Y. Chi 9 DISC LVDS output at discriminator board DISC output after ~10 meter cables 69 ns time difference 1.61ns/ft ~42 ft Digitally subtracted pulse between + and – side of discriminator LVDS output 500mv per division 1.4V 1.63V Long output cable study 1
Sept 25, 2008 PHENIX RPC review C.Y. Chi 10 Short Cable Disc threshold TDCTDC 79 ft cable (~24 meters) Long output cable study 2 100 mv/div 50ns/div The station 3 cable length could be along as 20 meters Although the result looks O.K., but this is in a lab environment. Digitally subtracted pulse
Sept 25, 2008 PHENIX RPC review C.Y. Chi 11 DISCDISC LVDS Receiver Trigger window 32 channel digitizer PLL Test Pulse LVDS Transmitter 4x beam clock 44X BC Test Pulse MASK Serial download Disc Serial download TDC serial download Interface Chip Collects 64 Channel Of Data Digitized Data L1 trigger etc L1 trigger primitives L1 trigger primitives Serial Download Timing etc. Event Data Event Data RPC TDC MODULE
Sept 25, 2008 PHENIX RPC review C.Y. Chi 12 The TDC Internal Test Pulse Scan test pulse step average TDC valueSigma on the TDC 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) TDC Module
Sept 25, 2008 PHENIX RPC review C.Y. Chi 13 RPC(HBD) crate/BUS structure 6Ux160 mm VME size TDCTDC TDCTDC Output To L1 Clock fanout L1 primitives L1 GTM Slow Control TDCs XMIT DCM Clock Master RPC FEM crate optical cable
Sept 25, 2008 PHENIX RPC review C.Y. Chi 14 Trigger data from FEM 1 pair of cable per FEM Arria FPGA De-serialized FEM data & format trigger data Transceiver blocks RPC Trigger Board Optical transmitter 2.8 Gbits/sec RPC triggers has been layout and proceed to fabrication. The module can receive up to 6 (8) FEM’s trigger data The optical trigger data contains, idle, clock numbers and up to 12 16bits FEM trigger data every beam crossing.
15 Channel count etc… (one side) Station1a+b3total Channel307228725944 Channel per FEM (TDC) 64 FEM (TDC)48 96 Disc Board96 192 L1 trigger Fibers 8816 FEM/ L1 fibers 66 Support board/crate 33 FEM/crate 12 Crates448 The discriminator board is mounted on chamber The TDC, Trigger module locate in the readout crate.
Sept 25, 2008 PHENIX RPC review C.Y. Chi 16 Production QA For discriminator boards We do even/odd channel direct pulse inject through a 12 bits DAC pulser vs. threshold We do on board test pulse test vs. threshold For TDC boards Fire the discriminator on board test pulse can check the data TDC internal test pulse scan Data to L1 trigger board test. ( still need to be works out)
Sept 25, 2008 PHENIX RPC review C.Y. Chi 17 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 designed and proceed to fabrication.
Sept 25, 2008 PHENIX RPC review C.Y. Chi 18 Production Outlook The production cycle normally last about 6 months. This include, fabricate boards, buy parts, board assembly and testing. For the RPC3 N discriminator board, we have most of parts on hand already. We will start production around Nov this year.