Abstract
Modules for the ATLAS Inner Tracker (ITk) strip tracker include a DC-DC converter circuit glued directly to the silicon sensor which converts the 11 V supplied to the module to the 1.5 V required for the operation of the readout chips. The DC-DC converter unit, consisting of a copper solenoid and custom ASIC, is located directly above the silicon strip sensor and therefore needs to be shielded to protect the sensor from EMI noise created during the operation of the circuit. Despite dedicated shielding, consisting of an aluminium shield box with continuous solder seams encompassing the surface components and a copper layer in the PCB beneath it, module channels connected to sensor strips located beneath the converter circuit were found to show a noise increase. While the DC-DC converter unit causing the underlying EMI noise operates at a frequency of 2 MHz, module characterisation measurements for ITk strip tracker modules are typically performed asynchronously to the DC-DC switching and are therefore averaged over the full range of time bins with respect to the converter frequency. In order to investigate the time dependence of the noise injection relative to the DC-DC switching frequency, a dedicated setup to understand the time-resolved performance change in modules was developed. By using a magnetic field probe to measure the field leaking through the shield box and triggering on its rising edge, data taking could be synchronised with the DC-DC switching. This paper illustrates the concept and setup of such time-resolved performance measurements using magnetic triggering and presents results for the observed effects on signal and noise for ATLAS ITk strip modules from both laboratory and beam tests.
Highlights
- Photovoltaic powered DC-DC boost converter based on PID controller for battery charging system M Irwanto, W Z Leow, B Ismail et al
: Modules for the ATLAS Inner Tracker (ITk) strip tracker include a DC-DC converter circuit glued directly to the silicon sensor which converts the 11 V supplied to the module to the
In order to allow a quantitative comparison of the module noise and S-curves with injected charge, magnetic triggering measurements were performed with an attenuated beam: aluminium attenuators with a combined thickness of 1.1 mm were used to reduce the beam intensity to 9.4%
Summary
S-curves obtained in time-dependent measurements without input charge showed that the noise occupancy at a given threshold, i.e. noise, is dependent on the phase of the trigger relative to the switching of the DC-DC converter. This effect is observed primarily in the vicinity of a shield box and, to a lesser extent, across the whole module. In figure 11, the no-beam Vt50 is 12 DAC while the proxy Vt50 with beam is 24 DAC This analysis of occupancy as a function of threshold with and without beam is performed on all channels investigated (every tenth channel running under the DC-DC area of the powerboard) for a range of latency values. The noise varies dependent on the timing with respect to the DC-DC switching but there is significantly less variation in noise as a function of position on the module (channel number)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
