應用於可饒曲基板之光震動感測器有機發光二極體驅動電路和光電感測器讀取電路設計

Abstract

本論文提出一有機發光二極體(organic light-emitting diode, OLED)驅動電路和有機光電感測器(organic photo detector, OPD)讀取電路設計，建構整合微機電系統(micro-electro-mechanical systems, MEMS)、有機發光二極體與有機光電感測器之振動感測器系統(Vibration sensor)，由OLED提供一穩定的光源，利用可移動式MEMS的光柵，因受到振動而產生位置的變化，使得OPD接收穿透光的光通量變化，因而偵測出精確的振動，開發完成之感測器能夠讓物理系統與電的訊號之間做好轉換。本論文著重在設計振動感測器之有機發光二極體驅動電路和光電感測器讀取電路，有機發光二極體驅動電路為使用脈衝寬度調變驅動取代一般常見的定電流驅動，脈衝寬度調變驅動電路為利用三角波與比較器產生的脈衝寬度調變訊號，並以此作為一電流源的控制開關。有機光電感測器讀取電路為使用轉阻放大器(Trans-impedance amplifier, TIA)作為前端讀取電路，將從有機光電感測器所得到的電流訊號轉成電壓訊號並放大，而此電壓訊號接著分為兩個通道，一為通過二階濾波器及類比數位轉換器取得振動值，二為通過比較器之後，由計數器讀出振動感測器所需之頻率值。本論文所設計的電路已使用台積電0.18微米CMOS製程下線製作成功，其總面積為1.012平方毫米，總功耗約為6.2 mW。PWM訊號頻率為200 kHz、duty cycle為50%，可結合光電元件與振動感測器測得10~1.5 kHz的頻率響應。

This thesis presents an organic light-emitting diode (OLED) drive circuit and an organic photo detector (OPD) readout circuits for a vibration sensor. Vibration sensor is consist of micro-electro-mechanical systems (MEMS), OLED and OPD which needs to be compact for many applications in automation or consumer electronics, and microelectromechanical structures are a convenient way to implement such sensors. The light flux is typically generated by an OLED located on top of the structure and the modulated light flux is measured by an OPD. The OLED drive circuit contains pulse width modulation (PWM) driver to control PWM output for optimization of voltage operation is designed in order to minimize power consumption efficiency of device. The readout circuit includes a trans-impedance amplifier (TIA) to convert incident light of OPD to voltage output, a 14-bit analog-to-digital converter (ADC) to extract amplitude of vibration level, circuit to generate clock for time-to-digital converter (TDC) which detect frequency of vibration sensor. The designed circuit has been successfully fabricated by using TSMC 0.18-μm CMOS process, where the active area is 1.012 mm2. The power consumption of chip is about 6.2 mW. The measured frequency of PWM signal is about 200 kHz and duty cycle is 50%. The frequency range of the vibration which could be sensed well is about 10 Hz~1.5 kHz.