One of PH/ESE’s flagship projects is the Radiation Hard Optical Link project for LHC, a common development for all LHC experiments and other interested collaborations. The objective of the project is to supply experiments with a radiation hard, magnetic field tolerant 4.8 Gbps data transfer link for all communication between detector front-ends and counting rooms. Based on point to point optical links it can handle timing signal broadcasted with low jitter, trigger transmission with deterministic latency, slow control, status monitoring and readout data. In this context, the ESE group designs, develops and qualifies (in collaboration with several international partners) all ASICs, Optoelectronic devices and ancillary electronics necessary to operate the link.

Within this project were thus already born several new devices, well known by the experiments and currently being produced in quantities reaching 80’000 pieces. These components are called GBTx (ASIC dedicated to serialization, deserialization and data and clock recovery), GBT-SCA (ASIC dedicated to slow control and status monitoring) and VTRx/VTTx (optical transceiver/dual transmitter designed at CERN and equipped with custom designed ASICs and qualified optical sub-assemblies). All of them are specifically designed to sustain the really high levels of radiations met within LHC detectors.

Each of them has been carefully tested and qualified against experiments’ requirements, however the community was lacking a simple way of testing and characterizing the complete system with all of them being interconnected.

The Versatile Link Demonstrator Board (VLDB) is the evaluation kit for the Radiation Hard Optical Link ecosystem. It gathers the three above-described radiation-hard ASICs and modules composing the main elements of the Link plus the FeastMP, a radiation hard in-house designed DCDC made of custom designed ASIC and qualified components.  

This board is the first design allowing system-level tests of the Link with a complete interconnection of the constitutive components. HDMI connectors allow to test communication with experiments Front-End electronics and to try multiple interconnection schemes between several VLDBs playing all the roles foreseen by the various use cases. It is a unique tool for initial characterization of the full Radiation Hard Optical Link ecosystem (in particular focussing on the quality of recovered clock delivered to the Front-End electronics, latency of delivered triggers or data link characterization). It is also the ideal guinea-pig to test software and firmware implementation at Back-End level and to control complex systems based on multi-GBT implementations. It will also be used for preliminary on-site system tests (underground, next to the LHC detectors) and for full radiation tests in several radiation facilities. Finally, it will be an excellent reference for future board designs using these components.

All these advantages made the VLDB an ideal learning platform to take in hand the Radiation Hard Optical Link system, and the ESE group decided to make the VLDB available to all interested users and produced a batch of them. 

It is coming with a full set of accessories (I2C programmer, breakout boards for GBT-SCA, elinks-FMC) and a set of firmware and software tools (a firmware core for GBTx and GBT-SCA communication, a web page to help creating custom configuration files, a GUI for GBTx control) . Support and training are also provided to the users to help them during the learning phase.

So far, 60 evaluation kits were produced and made available to users from many institutes over the world. A few of them are still available. A perfect Christmas Gift for you or your colleagues!