PFC-16 Preamplifier Filter Card Description ----------------------------------------- Original Rev. 4-JUNE-2007 Current Rev. 12-DEC-2007 This file is a general description of the 16 channel Preamplifier Filter Card (PFC-16) for T962. This description begins with a set of requirements and goals for the design of the PFC-16 card. As always the intent is to fully define the PFC-16 before any detailed layout work starts. - This design is based on: The T962 DAQ System not having more than 480 channels. The maximum event rate not being more than 1 event every 1.6 seconds There being no need for trigger signals to come out of the DAQ front-end electronics. There being no need for a zero suppressed readout from the DAQ System hardware. - PFC-16 will be made about the size of a standard 6U by 160mm VME card. It will be 233.0mm tall by 180.0 mm wide. Standard VME is 233.35mm tall by 160 mm wide. Note that this is slightly taller and significantly narrower than the PMB-16. The PMB-16 is 230 mm tall and 240 mm wide. The intent is that we can stack the PFC-16 cards in normal 6U "VME" card file mechanics. - Inside of the inner shield box the PFC-16 cards will slide into a EuroCard (VME) card file. This will give them a pitch of 0.8". This card file could hold up to 21 PFC-16 cards. - The PFC-16 will use a 2x17 0.1"x0.1" 90 degree header connector for the signal inputs. The input for channel #0 on the PFC-16 card is pin #2 of this connector. PFC-16 channel #15 input is on pin #32. All odd number pins are Signal Grounds. Pin #34 is not used and is grounded on the PFC-16 card. - The PFC-16 card will use use just one 3M 36 pin MDR type right angle output connector vs the three output connectors on the PMB-16 card. This single output connector will carry the output signals from all 16 channels on the PFC-16 card and thus the ADF-2 card can only operate in its full 32 channel mode, i.e. provide circular buffers that are 2048 steps long. The pinout of the connector will chance compared to the PMB-16 so that straight through routing can be used on the PFC-16 card. This means that the readout order for the PFC-16, as seen by the ADF-2, will be different than when reading out the PMB-16 cards. This can be "hidden" in the DAQ-96 System table that maps VME address to channel number. - The preamp on the PFC-16 card will be the same circuit as the FET stage of the D-Zero Run II hybrid preamp. This will be setup with a 2.0 pFd effective feedback capacitor (i.e. 0.5 mV output per femto Coulomb input) and a 20 Meg Ohm feedback resistor. The value of the feedback resistor should be optimized based on test in the PAB Bo LArTPC. A clean draft layout of this was done that fits in 10mm x 40mm. This is nicely within the 12mm channel pitch of the existing PMB-16 layout. - The filter section of the PFC-16 can be the same layout as the PMB-16 card. A big question is what filter constants to use. My hope is that this can be guided by experience with real tracks in the PAB Bo LArTPC before the assembly of the PFC-16 cards takes place. There are 3 basic options for filtering: do a full nice appropriate filter in the analog section of the PFC-16, do minimal analog filtering on the PFC-16 (just enough to keep the input to the ADC within range) and then do a digital filter in the ADF-2 FPGA (whether such a filter will fit depends on the filter design), do a minimal analog filter on the PFC-16 and no digital filter in the ADF-2 FPGAs but rather do a fancy filter in the offline software. - In order to have enough ADF-2 cards to service all 480 wires in T962 we will need to use some of all of the "species" of ADF-2 cards. These species differ only in their full scale analog input range. To take care of this we will need a mechanism on the PFC-16 cards to adjust their gain (i.e. femto Coulombs input to Volts differential output) to match the full scale sensitivity of the species of ADF-2 card that a given PFC-16 channel is working into. In the end we want the same number of ADF-2 card ADC counts per femto Coulomb of input to the PFC-16 across all channels. The PMB-16 was designed to drive the "C" species of ADF-2 cards. Thus the overall gain of the PFC-16 needs to be able to reach 5.5 / 4 = 1.375 times that of the PMB-16. The full scale sensitivity of the 4 species of ADF-2 cards are the following: ADF-2 Volts Diff ------------ Number ADF-2 EM HD TT Eta Range were of Cards Species F.S. F.S. this Species Is Used Manufactured ------- ---- ---- -------------------- ------------ A 4.0 2.0 1:4 21 B 5.5 3.5 5:8 21 C 4.0 4.0 9:12 21 D 5.5 5.5 13:16 and 17:20 37 - On the PFC-16 cards the gain adjustment to match the various species of ADF-2 cards is made in the Single-Ended to Differential Buffer Stage that sits between the FET Input Stage and the "classic" filter stages from the PMB-16 design. This buffer stage also provides the gain that was supplied by the "cable driver" section of the D-Zero hybird preamp. The nominal gain of the D-Zero hybird preamp cable driver stage was 6, i.e. 1 unit of single-ended input made 6 units of differential output. Thus the Buffer Stage on the PFC-16 will need to be able to provide the following single-ended input to differential output gain values: ADF-2 Input Volts Differential Full Scale ------------------------------- Required PFC-16 "Nominal" "Exact" Buffer Stage Gain ADF-2 ----------- --------------- ----------------- Species EM HD EM HD EM HD ------- ---- ---- ----- ----- ------- ------- A 4.0 2.0 4.087 2.120 6.00 3.11 B 5.5 3.5 5.439 3.491 7.98 5.13 C 4.0 4.0 4.087 4.087 6.00 6.00 D 5.5 5.5 5.439 5.439 7.98 7.98 - The above plan for a number of different gains for different channels of the PFC-16 card is nice but it is complicated to implement (because a given PFC-16 card will need a number of different gains (to match the EM vs HD split on the "A" and "B" spicies ADF-2 card) and thus the required versions of PFC-16 cards can not all be built by simple "reel substitution" on the pick and place machine) and it is probably not necessary to implement because of the sufficient dynamic range on the ADF-2 and there is only a factor of 2.566 between the sensitivity of the "A" species HD channel and the "D" species. Thus make the decision to build all of the PFC-16 cards with the Buffer Stage Gain set for the "D" type ADF-2 cards. - The primary signal ground connection to the PFC-16 cards will need to be along the input connector edge. We need to think of a clean way to implement this and still have the PFC-16 cards be easy to individually remove without un-stacking them as is necessary with the PMB-16 cards in the PAB Bo LArTPC system. This primary signal ground connection from the input edge of the PFC-16 cards must connect directly to the signal feedthrough flange via a wide copper conductor. - The power connection to the PFC-16 cards is via 2 connectors both on the output connector edge of the PFC-16. There is one power connector for the preamp section and a separate power connector for the filter section. The buffer stage also runs from the filter power. Preamp power is +8V and -6V. Filter power is +5V and -5V. - The power cables that plug into the PFC-16 cards must include the ferrite cores to break the ground loops. The power return connections are made through these cables (i.e. not via the signal grounds on the input edge of the PFC-16 cards). This power distribution cable assembly must also include the fuses to protect the power distribution setup so that this system can get an operating permit at Fermi. It may be easiest to make parts of this power distribution assemble as a pcb but note this is not a backplane setup. The bulk of this power distribution assembly will be mounted between the outer and inner shield boxes. - The expected power requirements are: Full Complete 480 Power per PFC per PFC Card File Channel System Supply Channel Card 21 PFC Cards 30 PFC Cards ----------- --------- --------- ------------ -------------- Preamp +8V 14.0 mA 224 mA 4.704 Amps 6.720 Amps Preamp -6V 3.5 mA 56 mA 1.176 Amps 1.680 Amps Filter +5V 38.7 mA 619 mA 13.003 Amps 18.576 Amps Filter -5V 38.7 mA 619 mA 13.003 Amps 18.576 Amps Total Watts 0.52 Watts 8.32 Watts 175 Watts 250 Watts Card File Power per PFC per PFC with Supply Channel Card 15 PFC Cards ----------- --------- --------- ------------- Preamp +8V 14.0 mA 224 mA 3.360 Amps Preamp -6V 3.5 mA 56 mA 0.840 Amps Filter +5V 38.7 mA 619 mA 9.288 Amps Filter -5V 38.7 mA 619 mA 9.288 Amps Total Watts 0.52 Watts 8.32 Watts 124.8 Watts - The preamp shield boxes will clearly require cooling. The options for providing this cooling include: forced air from a blower mounted on the shield box (issues of space and vibration), forced air from a remote bower, or water cooling (a significant complication for such a small system). The best setup is to blow cool air in from the input side of the PFC-16 cards to keep the FETs as cool as possible. - Input Connector The input connector J1 is a standard 34 pin (2x17) 4 wall header with latches. All odd pin numbers and pin number 34 are tied to the signal ground planes on the PFC-16 card. The PFC-16 Input Connector pinout is the following: J1 Input J1 Input PFC-16 Connector PFC-16 Connector Channel Pin Numbers Channel Pin Numbers Number Signal GND Number Signal GND ------- ------------- ------- ------------- 0 2 1 8 18 17 1 4 3 9 20 19 2 6 5 10 22 21 3 8 7 11 24 23 4 10 9 12 26 25 5 12 11 13 28 27 6 14 13 14 30 29 7 16 15 15 32 31 Pins: 33, and 34 are both GROUND. - Output Connector The output connector J2 is a 3M 36 pin MDR type right angle connector 3M Part No. 10236-55G3VC. The pinout of the output connector is the following: J2 Output J2 Output PFC-16 Connector PFC-16 Connector Channel Pin Numbers Channel Pin Numbers Number Dir Comp Number Dir Comp ------- ------------ ------- ------------ 0 2 20 8 10 28 1 3 21 9 11 29 2 4 22 10 12 30 3 5 23 11 13 31 4 6 24 12 14 32 5 7 25 13 15 33 6 8 26 14 16 34 7 9 27 15 17 35 Pins: 1, 18, 19, 36 and the connector shell are all GROUND. - PreAmp Power Connector The preamp power connector is a 6 pin 2x3 header without walls. It has the standard pin numbering with pin #1 in the upper righthand corner and pin numbers alternating the two rows as you move along the connector. The preamp power connector has the following pinput: Pin Power Cable Pin Power Cable Num Supply Color Num Supply Color --- -------- ----- --- -------- ----- 1 PAMP_VCC Red 4 GROUND Black 2 PAMP_VEE White 5 PAMP_VEE White 3 GROUND Black 6 PAMP_VCC Red - Filter Power Connector The filter power connector is a 6 pin 2x3 header without walls. It has the standard pin numbering with pin #1 in the upper righthand corner and pin numbers alternating the two rows as you move along the connector. The filter power connector has the following pinput: Pin Power Cable Pin Power Cable Num Supply Color Num Supply Color --- -------- ------ --- -------- ------ 1 FLTR_VCC Yellow 4 GROUND Black 2 FLTR_VEE Blue 5 FLTR_VEE Blue 3 GROUND Black 6 FLTR_VCC Yellow - Ground Connections