醫學影像感測電路設計

Medicine Image Sensor Circuit Design

傅嘉韋(Fu, Chia Wei)

指導教授 ： 盧志文

國立清華大學/原子科學院/工程與系統科學系/碩士(2015年)

摘要

正電子發射計算機斷層掃描(PET)系統需要Scintillator Elements 偵測光子，偵測光子後可由multi-channel photomultiplier tubes (PMTs)獲得所需要的空間解析度，或是由SiPM (Silicon Photomultiplier)來將光轉換成電流。本論文的電路設計是為了要應用在SiPM-based PET系統中，所設計然後考慮的。
此篇論文是在說明如何設計類比電路偵測一個約200奈秒的脈衝訊號，因為在電路前端會有核輻射光偵測二極體會在偵測到特定核輻射線時產生一個約200奈秒的脈衝訊號，因此電路架構設計是將此脈衝訊號放大然後進行積分，以便降低後端類比數位轉換器所需要的取樣時間， 並且產生一個類比數位轉換器所需要的觸發取樣訊號，因為電路都屬於多通道的設計，面積上的限制，我們無法整合在同一個晶片裡，所以先分別做成兩個晶片。
在內文中會介紹此電路的實現方法及考量，最後附上本論文使用TSMC 0.35UM技術設計和晶片量測結果。電流放大電路有約五倍的放大；電壓積分電路在輸入範圍40mv~370mv間，輸出差值的範圍在-1.42~2.31v，穩定時間約為640ns。

關鍵字

電流放大電路 ； 電壓積分電路 ； 類比數位轉換電路

並列摘要

Positron emission tomography system needs scintillator elements to detect photon. After detecting photon, it can be analyzed by multi-channel photomultiplier tubes to get enough space resolution or by silicon photomultiplier changing light into current. In this thesis, the architecture of circuit is based on silicon photomultiplier to consider and design.
This thesis will introduce how to design an analog circuit to detect a pulse signal about 200 ns, because in front of the circuit there is a nuclear radiation detector diode. When it detects the specific nuclear radiation it will generate a pulse about 200 ns. The circuit will amplify the pulse and then integrate it to reduce the sampling time of the back-end analog to digital converter sampling time. The circuit will also generate the trigger signal to tell analog to digital converter when to sample the input signal. The circuit is multi-channel we part the function into two chips one is for amplifying the current and the other is for integrating the voltage input, because of the limitation of area.
In this thesis will introduce about how to realize this circuit and all consideration. In the end of this thesis, TSMC 0.35μm technology is discussed with design flow and measurement results. About five times amplification of the current amplify circuit. About the voltage integrator circuit the input range is 40mv from 340mv and the output difference range is -1.42 from 2.31v. The stable time is 640 ns.

參考文獻

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