There are one buffer board per quadrant per superlayer at ASDQ end for SL1~3, per octant per superlayer at ASDQ end for SL4~8. The total amount is 52 boards. Each buffer board is sandwiched by two pieces of metal that shield the noise and bring away the heat.
Here is a table of the their locations.The cell numbers give where the buffer board jumpers connect. The buffers therefore reside between this cell and the adjacent, lower-numbered cell.
| Quadrant | A | B | C | D |
| Superlayer | Cell | Cell | Cell | Cell |
| 1 | 22 | 56 | 106 | 144 |
| 2 | 28 | 70 | 118 | 172 |
| 3 | 32 | 86 | 144 | 172 |
| Octant | A-1 | A-2 | B-1 | B-2 | C-1 | C-2 | D-1 | D-2 |
| Superlayer | Cell | Cell | Cell | Cell | Cell | Cell | Cell | Cell |
| 4 | 18 | 42 | 100 | 126 | 164 | 186 | 236 | 268 |
| 5 | 18 | 46 | 116 | 144 | 188 | 216 | 272 | 310 |
| 6 | 26 | 70 | 124 | 168 | 220 | 264 | 316 | 356 |
| 7 | 20 | 76 | 136 | 188 | 240 | 294 | 352 | 400 |
| 8 | 30 | 88 | 152 | 212 | 272 | 328 | 394 | 448 |
The main function of the buffer board is to stablize control voltages of ASDQ daughter boards. Control Voltages are set by the DAC modules in COT VME crate. One DAC module has 32 channels (only 24 channels are used) and sets the voltages of 4 superlayers on a quadrant. The ouputs of DAC are brought to a piggy-back board in Morris' low voltage box. This piggy-back board takes +-5V from the two 5V Condor power supplies and the outputs from the DAC to four 10-pin connectors. Then these voltages are carried by the four flat cables to the chamber face. For SL4~8, there are additional fanouts from quadrant to two octants.
Each buffer board takes the outputs of the piggy-back board as its inputs. Through three one-to-one operational amplifiers, buffer board can provide enough current to large amount of ASDQ DBs and the control voltages will not be brought down because of the small load. On top of that, the -3V on the buffer board comes directly from the -3V that supplies ASDQ DBs. This -3V behaves like a reference voltage to the calibration charge voltages (TREFE,TREFO, see below). The outputs of buffer board go to the CV board through a jumper cable.
On each ASDQ daughter board, there are six control voltages which allow us to vary the setting externally. They are DTHR, QDR, TREFE, TREFO, ATTEN and QEN. DTHR is the leading threshold that determines the point when signal starts to be triggered. QDR stands for trailing edge drain current and varies the width of ASDQ output. TREFE and TREEO are reference voltages of calibration pulses on even and odd channels.They dertermine the amount of charge injected to the pre-amplifier of ASDQ chips. ATTEN channel can be turned on to attenuate the charge by a factor of two. QEN channel can be turned on to do dE/dx measurement.
| Dimension | 1.7 inches X 2.7 inches X 200 mils |
| Number of Layers | 4 (top (component), ground, power, bottom) |
| Power | +- 5V |
| Input and Ouput Connectors | AMP Micro-MaTch through hole connector |
| Temp under normal operation | 298 K |
| Current needed under settings 1 | 325 mA |
| Current needed under settings 2 | 335 mA |
Settings 1: ATN=0V, QEN=0V, TRE=2V, TRO=2V, DTHR=400mV, QDR=1V for
SL7C2
Settings 2: ATN=3V, QEN=3V, TRE=2V, TRO=2V, DTHR=400mV, QDR=1V for
SL7C2
Any comments? Send e-mail to eiko@penn01.fnal.gov
Last updated on 09/11/2000 by Shin-Shan Yu.