Analysis and Design of Front-end Amplifier Circuits Utilizing Feedback Techniques for Communication Systems

本論文研究方向是著重於研究無線與有線類比前端接收機裡的必要零組件，包 括了低雜訊放大器和轉阻放大器與後端限制放大器。 幾乎在任何通訊系統當中，放大器扮演著非常重要的關鍵角色，如增強所期望 的信號功率、減少頻道的雜訊效應並且達到阻抗匹配的作用。在無線通訊系統中， 低雜訊放大器被廣泛地作為射頻接收機前端之第一級放大器，用以提供足夠的增 益來放大輸入信號，同時保有低雜訊性能。因此，在本論文裡，實現了兩個CMOS 低雜訊放大器的電路設計。一個電路是使用正回授技術操作在微瓦特功率消耗下， 應用於ISM 頻帶(5.8 GHz)；另一個電路是在無使用電感峰值技術下實現了寬頻 帶輸入匹配和高功率增益應用於超寬頻帶。此外，這些低雜訊放大器的電路設計 與設計上之考量均有詳細地描述說明並且實驗結果也展示出了不錯的性能指 標。 而在光通訊系統之接收機前端中不可或缺的零組件，轉阻放大器被作為第一組 成單元，廣泛地用於將檢光二極體所產生的微弱電流信號轉換成電壓信號。然而， 轉阻放大器的輸出擺幅無法提供足夠大的電壓位準。因此，跟隨轉阻放大器之後 的高電壓增益放大器將有必要提升轉阻放大器的輸出電壓擺幅。為了有效地減小 電路面積，在晶片內無使用任何電感器當中，提出了單端轉差動轉阻放大器與後端限制放大器。這個無電感式差動轉阻放大器與後端限制放大器的電路設計與設 計上之考量也均有詳細地描述說明。所製作出的無電感式差動轉阻放大器與後端 限制放大器能具有59 dBΩ 的轉導增益和9.7 GHz 的-3dB 頻寬。因此，它仍然足以操作在12.5Gb/s 的傳輸速率。The aim of this dissertation is to develop some essential building blocks in wireless and wireline receiver analog front-ends, namely the low noise amplifier (LNA) and the transimpedance amplifier (TIA) with limiting post amplifier (PA). Almost in any communication systems, amplifier plays critical role in order to boost the desired signal power, reduce the effect of in-band noise and achieve impedance matching. In a wireless communication system, the LNA is widely employed as the first stage amplifier of the front-end of receiver to provide sufficient gain for amplifying an input signal while maintaining low noise performance. Therefore, in this dissertation, circuit designs of two CMOS LNAs are developed. One employs positive feedback technique to operate at microwatt power consumption for ISM band (5.8 GHz) applications; the other achieves broadband input matching and high power gain without inductive peaking technique for ultra-wideband (UWB) applications. Besides, the circuit analysis and design considerations of these LNAs are described in detail and the experimental results demonstrate a good figure of merit (FOM). Being an essential component in the receiver front-end of an optical communication system, a TIA is widely utilized as the first building block to convert the weak current signal from the photodiode into a voltage signal. However, the output swing of the TIA does not provide adequate voltage levels. Therefore, following the TIA, a high voltage gain amplifier is needed to further boost the output voltage swings of the TIA. In order to efficiently reduce the circuit area, a single-ended-to-differential (S2D) TIA followed by a limiting PA is presented without any on-chip inductors. The circuit analysis and design considerations of the inductorless TIA and limiting PA are also presented in detail. The fabricated inductorless TIA with limiting PA exhibits a transimpedance gain of 59 dBΩ and a wide -3dB bandwidth of 9.7 GHz. Therefore, it is still sufficient to operate at 12.5-Gb/s data rate.致謝 ……………………………………………………………………Ⅰ 摘要 ……………………………………………………………………Ⅲ Abstract ………………………………………………………………Ⅴ Table of Contents……………………………………………………Ⅶ List of Figures …………………………………………………………Ⅹ List of Tables ………………………………………………………ⅩⅢ Chapter 1 Introduction ………………………………………………1 1.1 Background and Motivation ……………………………………………1 1.2 Literature Survey …………………………………………………………3 1.3 Dissertation Organizations ………………………………………………5 Chapter 2 Examples of Amplifier Design Using Feedback Techniques─Block Diagram Level Approach ……………………………………7 2.1 Introduction ………………………………………………………………7 2.2 Fundamentals of Negative and Positive Feedback Network …………8 2.2.1 Amplifier with Negative Feedback ………………………………8 2.2.2 Amplifier with Positive Feedback …………………………………11 2.3 Multistage Amplifier with Dual-loop Feedback Configurations …………………14 2.3.1 Multistage Amplifier with Interleaving Active Feedback ………14 2.3.2 Multistage Amplifier with Dual-loop Active Feedback …………17 2.4 Summary ………………………………………………………………20 Chapter 3 An Ultra-Low Power LNA ………………………………25 3.1 Introduction ……………………………………………………………25 3.2 Common-Source Amplifier with Positive Feedback Network ………26 3.3 Analysis and Design of Cascaded LNA ………………………………29 3.3.1 Input Impedance and Input Matching Network …………………30 3.3.2 Input Impedance and Input Matching Network …………………31 3.3.3 Output Impedance and Output Matching Network ……………35 3.3.4 Noise Figure Analysis ………………………………………………36 3.3.5 Linearity Consideration ……………………………………………40 3.3.6 Stability Consideration ……………………………………………44 3.3.7 PVT Variations Consideration ……………………………………48 3.4 Experimental Results …………………………………………………49 3.5 Conclusion ………………………………………………………………58 Chapter 4 An UWB LNA ……………………………………………..59 4.1 Introduction ……………………………………………………………...59 4.2 Analysis and Design of Inductorless Wideband LNA ……………60 4.2.1 Input Impedance Analysis …………………………………………61 4.2.2 Voltage Gain and Frequency Response …………………………61 4.2.3 Noise Analysis ………………………………………………………66 4.2.4 Linearity Analysis …………………………………………………68 4.2.5 Stability Consideration ……………………………………………70 4.2.6 Measurement Consideration ………………………………………71 4.3 Experimental Results ……………………………………………………72 4.4 Conclusion ………………………………………………………………78 Chapter 5 An Inductorless TIA with Limiting PA …………………79 5.1 Introduction ……………………………………………………………79 5.2 Analysis and Design of S2D TIA ………………………………………81 5.2.1 Input Impedance Analysis …………………………………………82 5.2.2 Transimpedance Gain Analysis …………………………………84 5.2.3 Input-referred Noise Current Analysis …………………………85 5.3 Analysis and Design of Post Amplifier …………………………………86 5.3.1 Bandwidth-enhanced Technique …………………………………86 5.3.2 Dual-Feedback DC-Offset Cancellation …………………………89 5.3.3 Output Buffer ………………………………………………………91 5.4 Experimental Results ……………………………………………………93 5.5 Conclusion ………………………………………………………………99 Chapter 6 Conclusion and Future Work …………………………101 6.1 Conclusion ……………………………………………………………101 6.1.1 An Ultra-Low Power LNA ………………………………………01 6.1.2 Dual-Feedback DC-Offset Cancellation …………………………102 6.1.3 An Inductorless TIA with Limiting PA …………………………102 6.2 Future Work …………………………………………………………103 6.2.1 An Ultra-Low Power LNA ………………………………………103 6.2.2 Dual-Feedback DC-Offset Cancellation …………………………103 6.2.3 An Inductorless TIA with Limiting PA …………………………104 Appendix—Conversion from Y-parameters to S-parameters…………105 Bibliography …………………………………………………………109 Publication List………………………………………………………11