RPC Front End Electronics n On chamber discriminator
RPC Front End Electronics n On chamber discriminator q q n The TDC board q q q n n The strips The CMS discriminator chips The discriminator board Test results The TDC and Crate block diagram The TDC board test result The trigger board The board counts Status July 10, 2008 PHENIX RPC review C. Y. Chi 1
RPC Strip n n 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. 3 m long, 4 cm or 2 cm wide. q 15/40 ohms impedance. 420 pf/160 pf capacitance. q Fully terminated strips. CMS endcap RPC q Cover 5/16 degree in phi, 7 to 38 mm in width and 22 to 55 cm in length q Un-terminated. q Lemo cables are used to connect strip to the discriminator board PHENIX RPC strip width range from 11. 4 mm by 141 mm to 64. 6 mm by 554. 2 mm. q The smallest one has 46 ohms impedance and 16 pf of capacitance. q The largest one has 10 ohms impedance and 286 pf of capacitance. July 10, 2008 PHENIX RPC review C. Y. Chi 2
CMS RPC preamp/discriminator chip Build on AMS 0. 8 um Bi. CMOS process, +5 V device. 15 ohms input impendence. 45 m. W/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 f. C up to 20 p. C with 1. 7 f. C ENC noise. Zero crossing is necessary to deal with large dynamic range. The time walk is about. 6 ns except for very large charge. Testing show that threshold level could be as high as 100 fc without loosing efficiency. All the chips has been fabricated. Two wafers has been packaged and tested. July 10, 2008 PHENIX RPC review C. Y. Chi 3
RPC 32 channel discriminator board Cable adapter board LVDS discriminator output Serial download 32 channels per board Fused +6 V input analog/digital power supply ~. 46 A (use +5 V, +3 V through low drop regulators) Serial download is used to set 10 bits 4 channel threshold DAC (4 mv per bin) and Fire test pulse. July 10, 2008 PHENIX RPC review C. Y. Chi 4
Connection diagram Half octant Module edge 3 M (Gray) 3432 -5302 Adapter Board 16 short RG 174 cables RPC disc 32 ch 3 M (Gray) 3417 -6640 2 -3 m cable ? 8 meters cable ? RPC TDC 64 ch 3 M N 3432 -L 302 RB 3 M 6834 -4500 PL Or 8534 -4500 pl 3 M 4640 -7300 3 M (gray) 3431 -5302 2 -3 m cable? Adapter Board 3 M (Black) D 89140 -? ? 3 M (Black) 34325302 RB July 10, 2008 8 meter cable ? Signal Cable : 40 conductors twist flat ribbon cable 3 M 1700/40 Twisted Pair, Flat Cable, . 050" 28 AWG Stranded PHENIX RPC Fire reviewrating VW-1 5 C. Y. Chi
On board test pulse vs. threshold study The discriminator is moving 4 mv per step. The test pulse is feed to the input amplify through 1 pf cap. (not for calibration, functional check only) Channel 14 TDC distribution, DAC step =80 TDC step July 10, 2008 PHENIX RPC review C. Y. Chi 6
Direct pulse injection (threshold effect) CMS Disc threshold Channel 26 Channel 28 TDC Channel 30 Channel 32 Threshold (8 mv per step) TDC distribution at step =20 (160 mv) Test pulse is set around ~ 4 mv input July 10, 2008 PHENIX RPC review C. Y. Chi 7
Direct Pulse Injection (fixed threshold) Channel 44 Channel 45 Channel 46 TDC disc. fired Input (steps) Inject test pulse through the cable adapter card + 10 pf capacitance (channel 45) 2 mv per step, 160 mv threshold (~80 fc) Cross talk seen at round 100 mv. July 10, 2008 PHENIX RPC review C. Y. Chi 8
DISC LVDS output at discriminator board 1. 4 V DISC output after 1. 63 V ~10 meter cables 69 ns time difference 1. 61 ns/ft ~42 ft Digitally subtracted pulse between + and – side of discriminator LVDS output 500 mv per division Long output cable study July 10, 2008 PHENIX RPC review C. Y. Chi 9
RPC TDC MODULE TDC serial download Trigger window L 1 trigger primitives Event Data Disc Serial LVDS download Transmitter MASK LVDS Receiver D I S C L 1 trigger primitives Interface Chip Digitized Collects 64 Data Channel Of L 1 trigger etc Data 32 channel digitizer Test Pulse Test PLL 44 X BC Pulse Serial download 44 X BC Serial Download Timing etc. Event Data 4 x beam clock July 10, 2008 PHENIX RPC review C. Y. Chi 10
TDC Module TDC: The TDC Internal Test Pulse Scan Use 44 X beam crossing clock to digitized the discriminated LVDS pulse, ~2. 5 ns for 9. 6 MHz RHIC clock test pulse step Sigma on the TDC average TDC value test pulse step Test Pulse: Generated internally with the FPGA with the same 44 x 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) July 10, 2008 PHENIX RPC review C. Y. Chi 11
RPC FEM crate L 1 primitives TDCs Output To L 1 XMIT Clock fanout Clock Master DCM L 1 Slow Control T D C GTM T D C RPC(HBD) crate/BUS structure 6 Ux 160 mm VME size July 10, 2008 PHENIX RPC review C. Y. Chi 12
RPC Trigger Board De-serialized FEM data & format trigger data Transceiver blocks Arria FPGA 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 6 FEM’s trigger data The optical trigger data contains, idle, clock numbers and up to 12 16 bits FEM trigger data every beam crossing. July 10, 2008 PHENIX RPC review C. Y. Chi 13
Channel count etc… (one side) Station 1 a+b 2 3 total Channel 3072 3848 2872 9792 Channel per FEM (TDC) 64 64 64 65 FEM (TDC) 48 64 48 190 Disc Board 96 128 96 380 L 1 trigger Fibers 8 16 8 32 FEM/ fibers 6 4 6 Support board/crate 3 4 3 FEM/crate 12 16 12 Crates 4 4 4 12 The crate size is like 6 U VME crate. I would like to limit the length discriminator cable to 10 meters. (to be tested about jitters) The RPC 2, 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. 14
Channel count etc with RPC 2/3 strips combined… (one side) Station 1 a+b 2 3 total Channel 3072 ~3848/2 ~2872/2 Channel per FEM (TDC) 64 64 64 FEM (TDC) 48 32 24 104 Disc Board 96 64 48 208 L 1 trigger Fibers 8 16 8 32 FEM/ fibers 6 2 3 XMIT to DCM 4 5 4 L 1 boards 8 8 4 FEM/crate 12 ~10 12 Crates 4 3 2 The crate size is like 6 U VME crate. I would like to limit the length discriminator cable to 10 meters. (to be tested about jitters) The RPC 2, 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
STATUS n n The discriminator and TDC modules has been successfully prototyped. Waiting for on chamber testing. q Grounding issue need to be resolved with chamber testing n n n 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. July 10, 2008 PHENIX RPC review C. Y. Chi 16
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