應用於下視網膜植入具互補式金氧半太陽能電池供電及影像與電源分區架構之電流刺激晶片設計

Abstract

本篇論文探討應用於下視網膜植入之互補式金氧半太陽能電池供電電流刺激晶片設計，包含感光二極體架構設計、光電池電源供應器設計、控制訊號產生器設計、刺激像素電路設計。在標準製程下的感光二極體架構設計中，我們提出兩種改良的垂直並聯式光電池架構，利用額外較深的二極體接面產生更大的光電流且克服了在體外生物實驗時會有漏電路徑的問題，並以台積電0.18微米標準製程所實作的測試鍵，在紅外線照射下，低金屬圍繞的雙層感光二極體所產生的光電流是高金屬圍繞的雙層感光二極體的2.1倍，在紅光照射下，雙層感光二極體所產生的光電流是單層感光二極體的4.36倍。為了驗證影像與電源分區架構系統的可行性，我們實作了一個植入用的高能感光二極體陣列晶片。高能感光二極體陣列晶片包含8x8像素的像素陣列，並有一時脈產生器，產生的參考時脈經由組合電路產生八個分區供電控制訊號。而高能感光二極體陣列晶片在雙光源系統架設下可以得到9.64μA電流輸出。針對正負刺激電流不對稱的問題，我們亦提出新的系統操作原理及內部刺激像素的修改並完成模擬。在台灣積體電路製造股份有限公司與國家晶片系統中心的幫助下，此晶片以0.18微米標準製程實現並驗證。基於上述特性，此光電池架構、視網膜晶片與電源控制系統對下視網膜植入的人工矽視網膜晶片設計上有相當程度的貢獻。

In this thesis, the design of CMOS current stimulation chips for subretinal prostheses is described. A new version of the on-chip photodiode called the multi-junction vertically parallel (MJVP) structure is proposed. It can generate a relatively large amount of current by utilizing the deeper PN junction and avoid the leakage path in vitro biological experiments. A photodiode testkey is designed, fabricated and verified in the TSMC 0.18μm CMOS standaard process. If incident light is IR, the output current of the two-layer Ndio which has lower height of metal is 2.1 times as large as the two-layer Ndio which has higher height of metal. Under illumination of red LED, the height of metal and photocurrent are related less. The unit two-layer The output current of two-layer Ndio is 4.36 times as large as the one-layer Ndio. The divisional images and power supply scheme (DIPSS) chips are designed, fabricated and verified in the TSMC 0.18μm CMOS standard process. The operation frequency of the high power capability eight-block DIPSS current stimulation chip is 81.25Hz and output stimulation current is 9.64µA by dual visible light source illumination. The positive and negative outputs current are asymmetrical problem of the DIPSS MPA chip is solved by the modified pixel circuits and operational principle. Because of its characteristic, the proposed DIPSS power management system can be considered as one of the highly integrated solutions for the subretinal prosthesis.