Hera-B OTr Front End Electronics

Hera-B OTr Front End Electronics

The Otr front end electronics consists of HV Boards, ASD-8 pre-amplifier cards, power distribution cards, TDCs and a couple of auxillary modules. For every component a short description, the latest layout and the prodcution status is given.


Conventions and Naming Schemes


Backplanes and Connectors


FE Electronics Meetings


Tests of FE Electronics


HV boards

Description

The HV boards are printed circuit boards connecting the chamber wires to the high voltage and to the pre-amplifiers. The boards are located inside the gas volume at each end of every chamber module. Different HV boards for the 5mm and the 10mm chamber modules, for the modules on the +x and -x side and for upper and lower end of the modules are needed.

The HV board has undergone several design iterations. The baseline solution is the so called new board from the Ljubljana group

The so called old design uses coaxial cables for the connection between boards and ASD-8 boards. The usage of the coax cable implied a very high man-power need and a large logistical effort in the production.

Layout

Material

Production

  • Old Boards Prodution at Bejing: Currently a limitted amount of old style HV boards is produced by Tsinhua University in China. They are foreseen for TC2- and PC4+ chambers.

    A pre-delivery of the TC2-/PC4- 5mm boards have arrived at DESY at the beginning of February ( list containing the boards ).

    The 10mm PC4- boards should stay in Bejing and will be mounted to the PC modules produced at IHEP and Tsinghua.

  • New Board Production: After the arrival of the pre-series and the successful mounting of the MC1 boards the production of the new boards have been launched. The full production takes place at Ljubljana rquires several shipments of material. For detailed information on the board production click Details on board production in Ljuljana .

  • Time schedule defined by chamber production

Mounting

  • for the mounting of the boards to the modules 5 different copper pieces are needed
  • the most outer wires of every module must be covered with a RYLSAN tube

Open Questions

  • Potting: the possibility of potting the boards with ECCO Bond is investigated

Feed-through boards

Description

The signal cables from the HV boards are plugged from the inside of the gas-box to the feed-through boards. On their outside the feed-through boards hold the ASD-8. In addition the feed-through boards are used to pass the HV to the inside of the chambers. There are tp principal types: boards with only ASD-8 conncetions (36 ASD-8 plugs) and boards with ASD-8 and HV connection (2x8 ASD-8 and 52 HV connections).

Layout

Board layout and geometry

Production

Produced by outside company: nnn boards already available from which mmm boards are delivered to Hamburg.

Needs in 98

4 new boards for MC-2 (already installed).

Information

Additional information can be obtained directly from Mario Pohl (Tel. DESY-Zeuthen +207).

ASD-8 pre-amplifier cards


Description

The ASD-8 pre-amplifier cards are based on the ASD-8B chip developed for the use under high radiation (SSC). The cards combine two ASD-8 chips with 8 channels each. Although the chip alows differential input signals, the positive signal input is connected (via xx pF) to ground. This is not true for the boards produced for the application inside the high-pt detector.

Layout

Board layout and geometry and the electronic's scheme

Production

So far the production of the ASD-8 was done in Zeuthen. Two assembly devices are available. The production speed of approx. 50 boards/day is limited by the time to solder the connectors. The Table summarizes the production status of the ASD-8 boards.
OTr Rich High pt All

need 7900 2000 850 10750
produced 2300 2000 850 5150
tested 1830 -- -- 1830
in HH 380 2000 850 3230
1830 -- -- 1830

Detailed List of OTr needs

Detailed List of ASD8 shipment, usage and availability

The production capacity of DESY Zeuthen is not large enough to ensure an ASD8 flow according to the needs of the superlayer assembly .

It is therefore necessary to get help from out-side companies: The PCBs of 2000 boards will be given to a company for complete board production including assembly and soldering of the connectors. Another 2000 boards will be assembled in Zeuthen. The connectors will be soldered by a company.

Needs in 99

Defined by the superlayer assembly schedule.

Test procedure

The ASD-8 chips as well as the boards are tested. For every channel the treshold U50 to record a standard test pulse with 50% efficiency is determined. The maximum difference of the reference thresholds of two channels of a single board should be less than 300 mV. The boards are grouped in bins according to their value (max - min)/2. The following 4 bins are used: 860...950, 960...1050, 1060...1150, 1160...x
As a second test the threshold Un at which the channels start to show noise (oscillation) is recorded.

The difference between U50 and Un is used to define 3 classes: greeen, blue, red.


class 1 2 3 4

green 7% 18% 10% 5%
U50 860...950 960...1050 1060...1150 1160...x
Un x...350 360... 450 460... 550 560...650

blue 10% 21% 7% 3%
U50 860...950 960...1050 1060...1150 1160...x
Un x...450 360... 550 460... 650 560...750

red 7% 4% 6% 1%
U50 860...950 960...1050 1060...1150 1160...x
Un x...550 360... 650 460... 750 560...850

Information

Additional information can be obtained directly from Mario Pohl (Tel. DESY-Zeuthen +207).

ASD-8 power distribution boards

Description

The ASD-8 power distribution cards serve two purposes:
  1. distribution of the +/- 3V power

  2. control of threshold voltages, survey of currents, and voltages and switching of the Test Pulser
For the survey and control functions the Philips SLIO chip is used: this chip provides a CAN bus interface and simple I/O functionality. Both a DAC and an ADC is integrated in the chip.

Layout

The boards of V2.1 and V2.2 differ in the supply voltage for the digital control part/logic (CAN) of the board. V2.1 uses 5V input while V2.2 has voltage stabilizer and uses 8V input voltage.

Production

A pre-series of 20 boards (type 6x8) was produced. This version (V1.0) is used for MC2, all the mini superlayers, and MC1. The boards of MC1/2 will be replace with boards of version V2.2 as soon as available. A total of 70 boards of version V2.1 are produced. There are meant for the installation in TC1-, TC2-, PC1- and PC4-. An order of the remaining 150 boards is going to be placed soon.

Needs in 99

Needs and required delivery schedule
Availability in Hamburg

Information

Additional information can be obtained directly from Mario Pohl (Tel. DESY-Zeuthen +207).

Time-to-Digital Converter

Description

For the time measurement and the digitization the Outer Tracker uses particular TDC boards designed by DESY and MSC. The main circuit at the OTr front end driver (FED) boards is the TDC chip. The TDC (time digital converter) chip is designed for HERA-B and accounts for the paticular data-taking conditions of this experiment. Each chip contains 8 time measuring channels with special GTL Input drivers. The least count of the 8-bit digitization is 0.5 ns. The measuring range correspond to the bunch clock cycle of 96ns. After digitization data is stored in a 128 cell deep digitalring buffer.

Production

The production of the TDC boards is done by MSC and has started end of April. The production speed is around nn boards per week. ??? boards have already been delivered and tested.

Layout

A picture of the TDC board and the electronic's scheme of the board

Documents/Notes

Information

Further information on the TDC or on the Hit boards used by RICH, Muon and Highpt can be obtained from : Michael Beck (Uni Rostock), Rainer Wurth (DESY) Raoul Zimmermann (Uni Rostock)

maintained by Uli / last modification Jan-24-99