4. lpGBT and VTRx+

The VLDB+ houses one lpGBT and one VTRx+ connector in the upper middle side of the board.

_images/lpGBT_VTRx+.png

Fig. 4.1 VLDB+ lpGBT and VTRx+

4.1. lpGBT

Almost the 100% of the lpGBT signals are made available on the VLDB+ through different interfaces such as VTRx+ connector, FMC HPC connectors, SMA connectors, simple pin connectors, testpoints, bullseye connectors and more. The availability of the lpGBT’s features on the VLDB+ are listed in the Section 13.

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Fig. 4.2 lpGBT V0 (left) and lpGBT V1 (right)

The VLDB+ V2 is lpGBT V1 compatible. That means that some VLDB+ V2 houses an lpGBT V1 instead of V0. Moreover, if an lpGBT V0 is housed on your VLDB+ V2, you have the option of desolder it and solder an lpGBT V1.

_images/lpGBT_reset.png

Fig. 4.3 lpGBT reset button.

Note

To reset the lpGBT you have to press the push button PB1. In the VLDB+ V1 (not the V2), as soon as the PiGBT Control Toolkit is connected to the VLDB+, pressing the PB1 will have no effect and its control is done through the PiGBT (reset button on the PiGBT web interface).

4.2. VTRx+

We can provide the VTRx+ module together with the VLDB+ (on request). The VTRx+ connector is the J14.

_images/VTRx+_standalone.png

Fig. 4.4 VTRx+ V10

Please note that only one Tx link is connected to the VTRx+ for simplicity reasons (refer to the Section 13.10).

The VTRx+ MT connector has 12 optical lines where only 2 (1 RX and 1 TX) are used to communicate with the lpGBT housed on the VLDB+. The following picture describes the VTRx+ MT connector:

_images/mt_connector.png

Fig. 4.5 MT connector of the VTRx+

The pre-production VTRx+ which we can provide together with the VLDB+ Kit, uses the lines 6 (VTRx+ TX) and 7 (VTRx+ RX) to transmit and receive data in case the MPO Fanout goes from channels 1 to 12.

To connect the VTRx+ MT connector to an MPO connector, you have to put the guide pins inside the MPO connector. Then, take a look at the keys from the MPO and MT connectors, both must be in opposite directions. The following picture shows the correct connection using both connectors.

_images/mt_mpo_connection.png

Fig. 4.6 Correct MT-MPO connection

Warning

The J14 connector has not a high durability. Please, avoid to connect and disconnect the VTRx+ repeatedly in order to preserve its durability.

4.2.1. Back-end MPO Fanout Patchcord

We do not provide the neccesary MPO Fanout Patchcord and the two MPO guide pins to interconnect the Evalution Kit FPGA transceiver and the VTRx+. However, at CERN you can request these tools opening a ticket here. Fill the .csv that they provide with the following:

Type Number Type Cnn. A Assembly Type de cord Cnn. B L More info.
Patch cable 12 Multimode 50/125 OM4 12-Fibres MTP/MPO (male) A (standard) 1 Fibre (Simplex) LC/PC 1 m 12 fiber fanout MTP to LC

The guide pins will be provided with the MPO connector.