臺灣博碩士論文加值系統

這篇論文提出了一個可操作在1伏供應電壓下且對於溫度變異具有高穩定性之軌對軌運算放大器。 其中包含一個修改過的共模調整器(CM adapter)和一個修改的能隙參考位準(bandgap reference)偏壓電路。 首先，修改過的共模調整器是利用電壓位準位移的方法使得0到1伏的輸入共模電壓都位移到低於0.1伏的電壓位準。 將這個電路作為我們所提出的運算放大器的前置電路，則PMOS差動輸入級可以工作在軌對軌的輸入共模範圍下。 其次，修改過的能隙參考位準偏壓電路是結合兩個擁有相反溫度係數的電壓來產生一個對溫度去敏感的偏壓電流並送到輸入級。 此外在這個電路中，如果將一個BJT和原來存在電路中的二極體串接，則二極體的接面面積可以減少，使得在實際應用上利用到更少的BJT並聯。
在1伏的供應電壓下將以上兩個修改過的電路應用在我們所提出的運算放大器中，並且使用台積電1P4M 0.35μm的CMOS製程。 在25℃時，直流增益為78.9 分貝且單位增益頻寬為3.73 MHz。 相位邊際達到42.9度。 當溫度從0度變化到75度，對於我們所提出的運算放大器，其頻率響應會對溫度去敏感，而直流增益的變化量為2分貝。 運算放大器的佈局也會在這篇論文中呈現，其面積為0.2 mm2。

A rail-to-rail op-amp with high stability over temperature variation at 1-V supply voltage is presented in this thesis. It incorporates a modified CM adapter and a modified bandgap reference. First, the modified CM adapter utilizes a level-shifting technique to shift the input common mode voltage of 0-1 V to the level below 0.1 V. By introducing this circuit as the front-end block of the proposed op-amp, the PMOS differential input stage can be operated appropriately with the rail-to-rail input common mode range. Second, the modified bandgap reference that combines two voltages with opposite temperature coefficients generates a temperature-insensitive bias current to the input stage. Besides, by the technique of cascading a diode with an additional BJT, the junction area of the original diodes can be reduced and in the actual application, fewer parallel-connected BJTs are needed.
The two circuits are applied to the proposed op-amp operated at 1-V supply voltage in TSMC 1P4M 0.35μm CMOS technology. At 25℃, the dc gain is 78.9 dB and unity-gain bandwidth is 3.73 MHz. The phase margin is 42.9°. For the temperature from 0℃ to 75℃, the frequency response is temperature-insensitive and the dc gain variation is 2dB. The layout view of the proposed op-amp is also presented and the area is 0.2 mm2.

Contents
Chapter 1 Introduction……………………………………………………1
Chapter 2 Basic Architectures of Bandgap Reference and Op-amps Based on Single Differential Pair……………………………………………………………5
2.1 The Op-amps Based on a Single Differential Pair…………6
2.2 The Op-amp Proposed by J. Francisco Duque-Carrillo………7
2.2.1 Common Mode Adapter………………………………………7
2.2.2 Overall Structure of the Op-amp………………………9
2.3 Bandgap Reference…………………………………………………9
Chapter 3 Modified Common Mode Adapter and Bandgap Reference………………………………………………………………………18
3.1 Modified Common Mode Adapter…………………………………18
3.2 Modified Bandgap Reference……………………………………19
3.3 The Op-amp with the Modified CMA and BGR Circuits………21
3.4 Modified BGR Providing a Bias Current………………………22
Chapter 4 Simulation Results of the Proposed Op-amp……………33
4.1 The Simulation Results of the Proposed Op-amp……………33
4.2 Layout View and Post Layout Simulation……………………34
Chapter 5 Conclusion……………………………………………43
Reference……………………………………………………………44
Appendix……………………………………………………………46

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