DESIGN OF GERMANIUM P-TYPE POINT CONTACT DETECTOR ASIC PREAMPLIFIER

Abstract

This Master's thesis investigates the preamplifier designs for High Purity Germanium (HPGe) detectors and compares their performance characteristics. The topic is important in the fields of nuclear physics, materials science, and medical imaging, as HPGe detectors are widely used in these fields. Despite the availability of various preamplifier designs, there is still a gap in the research regarding the optimization of these designs. The main focus of the work carried out is to analyze and study the existing designs of preamplifier circuits for HPGe detectors, compare their performance characteristics, and create a new design with improved parameters of noise, gain, and rise time. This new design is based on several special modifications, such as optimizing the input stage, refining the feedback loop, and enhancing the power supply rejection ratio. The study utilized simulation and analysis methods in Orcad software to evaluate and optimize the preamplifier circuits. The key message of the thesis is the optimization of preamplifier designs for HPGe detectors, yielding significant improvements in performance characteristics. The final implemented preamplifier design demonstrated a rise time of 3.58 ns, voltage of 15.276 V, and noise of 1301 eV with a 50 pF detector capacitance. This improved design is compared to a widely-used existing design, referred to as the "previous design," which had a rise time of 6.68 ns, voltage of 13.42 V, and noise of 1441 eV. The complexity of the new design has been kept simple, low cost, and with low power consumption, making it a promising candidate for practical applications. The research contributes to the field of preamplifier design for HPGe detectors by providing valuable insights into the optimization of preamplifier designs, demonstrating significant improvements in performance characteristics. The key optimizations include enhancing the input stage, refining the feedback loop, and improving the power supply rejection ratio. The Printed Circuit Board (PCB) design creation and feasibility analysis of chip fabrication further demonstrated the potential for applying the optimized preamplifier designs in practical applications. Overall, this research provides a promising solution for improving the performance of HPGe detectors, benefiting various fields such as nuclear physics, materials science, and medical imaging.