Speaker
Description
Summary
Recent studies have shown that the requirements of the
Preshower for on-line data-
reduction cannot be met by existing readout hardware
designed for use by other CMS
sub-detectors. Hence the need for the development of a
CMS Preshower data
concentrator card coincided with similar requirements with
the TOTEM experiment.
This gave birth to the idea of a modular VME readout
system, common to both systems.
This will allow selection of which constituent modules are to
be used, depending on
the requirements of each system. The idea of a modular
system is also very
attractive because it can speed up production, by sharing
development between
different labs.
The principle element of the new VME readout system is the
plug-in module used for
reception of optically transmitted data by the front-end
electronic systems. The
optical receiving module is based on a 12-channel optical
receiver and an FPGA with
embedded deserializers. The 12-channel digital optical
receiver (NGK’s POR10M12SFP)
used is the one specified for the CMS ECAL optical links. The
FPGA used (Altera’s
Stratix GX family) incorporates up to 20 embedded hardware
deserializers with data
rate up to 3.125 Gbps. The FPGA is compatible with both the
Gigabit Ethernet (8b/10b
encoding) and G-Link (CIMT encoding) protocols supported
by the GOL serializer ASIC
used in the front-end systems of both the Preshower and
TOTEM. The deserialized data
are provided by the FPGA to the parallel output bus which
can be up to 216 bits
wide. A 64-bit bidirectional bus is reserved for controlling the
module. The optical
receiving module also provides an optional connector on top,
for attaching an S-
Link64 transmitter mezzanine card, if required (i.e. for the
TOTEM front-end
driver). In addition, an optional electrical gigabit serial
output is provided for
future use. Although the total number of interconnections is
large, its size was
kept relatively small (7.5cm x 11.5cm), allowing several of
these modules to be
plugged onto a VME-9U board.
The functionality of the module has been tested with both
the CMS Preshower front-
end electronic system and the TOTEM front-end system
emulator, and its behavior been
deemed satisfactory. Some additional tests done with the
PILOT ASIC have shown that
the module could also be used for the readout of the ALICE
silicon pixel detector.
Besides forming the basis of the CMS Preshower data
concentrator card and the TOTEM
front-end driver, it is envisaged that this compact plug-in
module will also be
useful for the readout of other detector electronics systems,
for LHC and beyond.
