- 學位論文
一個應用時間增益補償的TSMC 180nm DMOS製程的微小化超音波液位計之設計
Design of a Miniature Ultrasonic Fluid Level Gauge Utilizing Time-gain Compensation in TSMC 180nm DMOS Process
摘要
市面上以鋰電池為電源供應的電子產品越來越多，包含電動車與手機等等。然而，鋰電池的安全與耐用度問題仍尚未完全解決，尤其在電動車的應用中，電池的蓄電力下降與爆炸問題，仍然是電動車存在的主要問題之一。本篇論文整理近年電池管理系統的研究，並依照其規格，設計出一微小化的量測系統。此系統亦能成為一超音波液位計，其不接觸到液體的特性，可有許多工業上的應用。 本系統由兩個晶片與兩個超音波換能器 (Transducer) 所組成，兩個晶片分別為發射器與接收器。發射器的製程為 0.18μm DMOS製程，其輸出為脈波，頻率為超音波換能器的共振頻率，目的為驅動超音波換能器。同時，發射器內部有 停滯時間控制器 (dead-time controller) 的電路，使晶片不會產生大的瞬間電流，以免在電動車內部的環境產生無法預估的化學反應。接收器的製程為0.18μm CMOS製程，晶片內部包含低雜訊放大器 (LNA)、自動增益控制器 (AGC)、帶通濾波器 (BPF)、包絡檢波器 (envelope detector)，接收器的目標是讀出接受訊號的時間及振幅大小。由於超音波在傳遞時會衰減，為了讀出不受衰減影響的接收訊號，時間增益補償(time-gain compensation) 會被應用在AGC內。此外，AGC有取樣保值電路(sample and hold circuit)，當晶片感應到接收訊號時，會對AGC控制增益大小的數位訊號進行取樣，並輸出此數位訊號。由於數位訊號是由計數器 (counter)所產生的，故此訊號亦可作為時間數位轉換器的輸出。 根據系統需求，整個系統內各個重要設計參數都進行詳細計算。本論文使用30V、5V、1.8V的電源電壓，接受器的類比前端輸入雜訊小於3nV/√Hz，而接收訊號時間的準確度小於5μs，兩顆晶片的總功耗約為55mW。此設計可與部分市售超音波液位計規格匹敵，能多方應用在許多產業中。
並列摘要
In the market, electronic products with lithium-ion batteries as power supply become more and more], including electric cars and cellphones, etc. However, safety and reliability are still problems to be solved for lithium-ion batteries. Especially in the application of electric cars, there remains gradual degradation and catastrophic failures for the electric cars. This dissertation reviews recent research on battery management system and design a miniature measurement system based on previous research. This system can also serve as an ultrasonic fluid level gauge, which utilizes its property of not exposing to liquid, in various industrial applications. The system is composed of two chips and two ultrasonic transducers. The chips are a transmitter and a receiver. The transmitter is realized by a TSMC 180-nm DMOS process, with pulse as its output signal and with frequency equal to the resonant frequency of ultrasonic transmitter, in order to drive the transducer. Meanwhile, there is a dead-time controller in the transmitter in order not to produce large current spikes to avoid unpredictable chemical reaction inside the electric cars. The receiver is realized by a standard TSMC 180-nm CMOS process. The receiver is composed of low noise amplifier (LNA), automatic gain controller (AGC), band-pass filter (BPF) and envelope detector. The target of the receiver is reading out the amplitude of the received signal and the received time. The time-gain compensation is applied in the AGC because we want to readout the signal without decay when the ultrasonic signals propagate. In addition, there is sample and hold in the AGC. When the chip senses the received signal, it will sample the digital signals which control the gain of the AGC, and exports the digital signal. Because the digital signal is produced by the counter, the signal can also be seen as the output of time-gain converter. According to system requirements, every parameter designed in the whole system is calculated deliberately. This dissertation uses 30V, 5V and 1.8V as power supply. The input-referred noise of the receiver is less than 3nV/√Hz, and the accuracy of the time received signal is less than 5μs. The power consumption of the two chips is 55Mw. This design is comparable to partial commercial ultrasonic fluid level gauge and has multiple applications in many fields.
參考文獻
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