Final evaluation of the analog optohybrid circuits performance for the CMS tracker inner-barrel and inner-disks

Silicon strip tracker detector of the Compact Muon Solenoid (CMS) experiment, presently under construction at the CERN Large Hadron Collider (LHC), consists of 9.3 million individual detector channels that are time-multiplexed (40 M sample/s) onto roughly 36,000 unidirectional analog optical links transmitting data from the detector and the counting room over a distance of 65 to 100 m. The analog optohybrid circuit (AOH), as part of this readout system, converts the amplified detector signals to amplitude modulated optical ones using a programmable linear laser driver (LLD) ASIC and two or three 1310 nm InGaAsP/InP multi-quantum well laser diodes. Due to the harsh radiation environments, strict requirements have been placed on minimal package size, mass, power dissipation, immunity to magnetic field and radiation hardness. Considering the CMS tracker inner barrel (TIB) and tracker inner disks (TID) subdetectors, approximately 3,700 analog optohybrids with two or three channels each are required in order to process the information coming out from the readout electronics. These circuits were designed and successfully produced in Italy, under the responsibility of INFN Perugia with the volume production phase completed by March 2005. The final features of the circuit, the relevant production steps (from laboratory prototypes to large-scale production) the quality assurance procedures as well as the most relevant qualification tests, with statistics results, are reported in this paper. A special attention has been paid on the comparison between AOH laboratory measurements results and the in-system performances measured on the real TIB structure during the October 2004 test beam held at CERN X5