應用於膽固醇液晶顯示器之單電感雙極性正負高壓輸出直流直流電源轉換器

Abstract

電子設備如今不只是被工作所需要，因應娛樂與互動式介面需求，或是靜態低消耗功率的電子閱讀器被消費市場所重視且快速發展。需要擁有長時間使用與待機的電子閱讀器，類紙式閱讀器中的膽固醇液晶顯示器，有別於市面上常見液晶顯示器，具有雙穩態特性，能夠在不更新閱讀器頁面之時穩定呈現。因此，為了有效使用有限的電池能量，電源管理系統為晶片系統中非常重要的一環。故本文提出一個運用於切換式電源轉換器的技術，以期在此切換式電源轉換器的電路中提供穩定之正負電壓驅動膽固醇液晶顯示器。 本論文所提出的內容，是運用單一輸入與單一外部電感，產生雙極性正負高壓輸出之直流直流電源轉換器。多組輸出電壓解決傳統切換式升壓電源轉換器所需較多外部元件，耗費面積的問題；以及解決傳統電荷幫浦電路低驅動能力與低效率之原有結構的缺陷。本系統亦使用多路複用技術，在單一周期即完成輸出電壓所需能量。 另外提出毋需外部幫助而自我偏壓之電荷幫浦電路，提供驅動訊號以幫助上述之單電感正負輸入之切換式電源轉換器，也具備較低驅動能力之多組電壓輸出以提供液晶顯示器灰階顯示。 本論文所提出的方法運用於電流模式直流/直流升壓正負電壓轉換器上，並用台灣積體電路公司點二五微米製程來實現。實驗結果顯示本論文的方法可在不增加太多額外的外部元件的前提下，提供多組正負電壓輸出以驅動膽固醇液晶顯示器。

In this thesis, a single inductor dual/bipolar high voltage outputs technique is proposed to generate dual outputs to provide driving capability of cholesteric liquid crystal display. Accompany with slope compensation and system compensation, two channel dc-dc converter with positive and negative high voltages can be proved stable. By this technique, it largely reduces area occupation comparing with boost converter producing multiple outputs and resolves the difficulty of efficiency and driving ability in charge pumping supplying system. Besides, the technique uses its unique property and makes it possible to integrate controller and energy delivery elements facing high voltages inside one chip. In addition, the concept of fully balanced self bias switching capacitor structure is proposed to offer specific driver for single inductor structure, and to generate multiple outputs with lower driving ability to apply to gray level implementation, which provides extra two functions to compensate the drawback of lower efficiency in its born defects. The test chip was fabricated by TSMC 0.25μm BCD process, and experimental results show the verification of maximum up to nearly 7V in positive channel and minimum down to near -20V in negative channel.