The future generation of the tracker system plans to develop a new power distribution scheme based on switching power converter technology. CMS have approved integrated research plans to study the real impact of the integration of DC-DC converters within the tracker subsystem in the noise and performance of the detector. A large effort in the DC-DC converter design is conducted to minimize the noise emissions. However, this effort has to be complemented with electromagnetic compatibility studies at the system level to allow predicting noises problems during the integration stage. The emission level of noise currents at the input/output of DC-DC converters depends strongly on the power network impedances connecting the converters to both the load and the source. The characterization of the noise emissions at the system level with regarding to the power network and FEE impedances, granularity and stray capacitances associated to the system will help defining good integration strategies. It will improve the electromagnetic noise rejection as well as estimate the noise emission level for the DC-DC switching converters to be installed in the final system.
This paper presents the effects of the network impedance and integration options (DC-DC converter location and granularity) in the current noise emission of the DC-DC switching converters. For that purpose a set of simulations and real measurements has been performed to measure the conducted and radiated noise emitted by the DC-DC converter with respect to different impedances. The conducted noise emission at the input and the output at system level have been evaluated. Also, radiation emission measurements from DC-DC converters are presented too. This is the first time that this kind of tests is carried in high energy physics. These measurements will be compared with common mode conducted emissions to establish a relationship between both radiated and CM conducted noise.
This paper will help to define a set of integration rules and strategies that will define the specifications, location, granularity and filtering performance degradation for the DC-DC converters. The main goal of this study is to anticipate and minimize the total amount of noise present in the Tracker environment and reduce the risks during the integration of the system.