Other Tests

The analog performance of optical link and FED was evaluated with very encouraging results. Their bandwidth is sufficiently high so that signals do not suffer from slow transients. Transfer characteristics, noise, linearity and other characteristics of the optical link were found to conform with their specifications. The final link will contribute about $600\,\rm e$ of noise referred to the APV input.

Both the APV25S1 and semiconductor lasers for the analog optical link have been tested in a magnetic field of up to $10\,\rm T$. No effect on the APV chip was observed, while the lasers revealed small shifts of a few percent in threshold current and gain, which are negligible with respect to the application in the CMS Tracker.