Description
The conversion of trigger events to their digital equivalent is a central component of any timing-based front end, with applications found in mass spectrometry, single channel analyzers, and a huge variety of 3D mapping and ranging systems. At the same time, ever- tightening size, weight, and power budgets for space launches with a skyrocketing (no pun intended) number of launches in the last decade have made application-specific integrated circuit solutions increasingly appealing. However, conventional analog methods of pulse discrimination introduce timing walk or are limited to a narrow range of pulse shapes, while early-stage digitization requires impractically high sample rates for the events in question.
This work presents the analysis, design, and measurement of an integrated constant fraction discriminator with theoretically zero timing walk and a programmable, constant trigger fraction which does not depend on input pulse shape. The specific silicon presented here was designed for the Solar Probe Analyzer for Ions as part of its time-of-flight mass spectrometer to determine the ion composition of space plasmas. This dissertation discusses the front end requirements for a radiation hardened pulse discriminator in the context of SPAN-Ion. We then address the architectural modifications used to achieve a pulse shape-independent constant trigger fraction, as well as the analog and digital hardening techniques required to detect, correct, and/or mitigate radiation-induced effects. Finally, this work presents the first attempt at an integrated pulse-shaping front end for SPAN-Ion, concluding with simulation results from a more recent chip and a discussion of future work both for SPAN-Ion and for further code base development.