Introduction:

The Optoboard System is the data aggregation and signal conversion stage of the ATLAS ITk Pixel data transmission chain. The basic working principle is:

• DATA: 6x 1.28 Gbps electrical links from the front-end modules are serialized into 1x 10.24 Gbps optical link and transmitted to the backend (FELIX).
• CMD: 1x 2.56 Gbps optical link with trigger and command are deserialized into 8x 160 Mbps electrical links and transmitted to the front-end (ITkPix). Also the Optoboard gets controlled through the optical link.

One Optoboard consists of:

• 4 lpGBTv1: one as a master available through IC, three as slaves controlled through I2C controller of the master. Manual/description here.
• 4 GBCR2: all controlled through lpGBT master I2C controller. Manual here.
• 1 VTRx+: controlled through lpGBT master I2C controller. Description here.
• 1 bPOL2V5 carrier board: houses the bPOL2V5 ASIC that converts 2.5 V to 1.2V. Datasheets here.

Specific for SLAC's test-Optopanel will be marked in red.

Mechanics:

• Up to 8x Optoboards are housed in one Optobox. One Optobox consists also of:
  • 1 Powerboard: hosts 5 bPOL12V ASICs (conversion 9 V to 2.5 V) and 1 MOPS chip
  • 1 Connectorboard: handles power distribution form the 5 bPOL12V to the 8 Optoboards according the SP chain powering/detector layout.
• Up to 28x Optoboxes (14x normal, 14x mirrored) are housed in one Optopanel.
• Each side of the ITk has 4 Optopanels.

Currently specific for SLAC IS demonstrator:

4x Optoboards are housed in one Optobox. This Optobox is housed in a Test-Optopanel.

Interfaces:

Please refer to our Interface Document here. All the connectors of the Optoboard System is explained there.

Schematics:

All schematics for all of Berns designed PCBs can be found here.

Optoboard sytem support:

We collect support requests and general questions on our Mattermost channel Bern-Optoboard (invite link).

Optoboard software for FELIX:

We created a repository with scripting software to easily configure the Optoboard: https://gitlab.cern.ch/bat/optoboard_felix. A lot is documented in the readme and wiki of the repository.

In a currently ongoing effort by Bern PhD student Daniele dal Santo, the software will be integrated into the ITk demonstrator software itk-demo-sw.

Test-Optopanel at SLAC:

The test-Optopanel houses one Optobox with 4 Optoboards. It has a twinax inlet (round) and a fibre outlet (rectangle). The Optobox is mounted on a cooling plate with two 8 mm pipes. The

A collection of photographs from the test-Optopanel and its sister at CERN SR1 can be found here. See also this Twiki here of the SR1 test-Optopanel which has similiar information (but some very different configurations).

Optoboards:

Connectors:

Banana plugs are labelled according to powered bPOL12V.

Cooling and dry air inlet/outlet: FESTO 8 mm

DCS:

Currently no MOPS is mounted on the Powerboard inside the test-Optopanel (due to availability). We will ship one as soon as we got our hands on them.