전원 잡음에 둔감한 고리 발진기와 디지털 위상 동기 회로 설계

학위논문(석사) -- 서울대학교대학원 : 공과대학 전기·정보공학부, 2023. 2. 정덕균.One of the critical blocks integrated into the PAM4-binary bridge, bridging the high-speed DRAM and the low-speed DRAM Tester, is an All-Digital Phase-Locked Loop (ADPLL). Since the transmitter and receiver operate based on the clock signal, whose frequency is doubled compared to the clock signal transmitted from the memory tester by the ADPLL, the ADPLL needs to have a low RMS jitter and high Process-Voltage-Temperature (PVT) tolerance characteristics. However, due to the complex bridge circuit sharing the supply power with the ADPLL, power supply noise (PSN) is the main challenge for the Ring Oscillator (RO) based ADPLL. This thesis presents a Supply Noise-Insensitive RO-based ADPLL. A supply noise absorbing shunt regulator composed of 31-bit NMOS transistors Array is embedded parallel to the RO. Output codes from the Digital Loop Filter (DLF) not only control the Digitally-Controlled Resistor (DCR) but also the transconductance of the NMOS transistor Array. The proposed ADPLL is fabricated in the 40-nm CMOS technology. The ADPLL occupies an active area of 0.06 mm2 and consumes power 13.5 mW, while the proposed scheme only takes 6.6% and 2.8% of it, respectively. At 8 GHz operation, the proposed ADPLL achieves an RMS jitter of 3.255 ps with 1-MHz 40-mVpp sinusoidal noise injected into the supply voltage. With the Supply Noise-Insensitive technique, the RMS jitter lowers to 1.268 ps.고속 DRAM과 저속 검사 장비를 연결하는 4단계 펄스 진폭 변조-2진법 브리지 칩의 주요 구성 회로 중에 디지털 위상 동기 회로가 있다. 이 회로가 검사 장비에서 온 참조 클락의 진동수를 2배로 빠르게 하여 출력하고, 그 클락을 기준으로 칩의 송수신 회로들이 동작하기 때문에 낮은 RMS 지터와 공정-전압-온도 변화에 둔감한 성능이 요구된다. 하지만, 칩의 복잡한 회로들 때문에 고리 발진기를 기반으로 한 이 회로에게 전원 전압 잡음이 가장 큰 문제점이 된다. 본 논문은 전원 잡음에 둔감한 고리 발진기를 기반으로 한 디지털 위상 동기 회로를 제안한다. 전원 잡음을 흡수하는 단락 레귤레이터 역할의 31-비트NMOS 트랜지스터 배열이 고리 발진기와 평행하게 구현되었다. 디지털 제어 저항을 조절하는 디지털 루프 필터에서 온 행 조정 비트들이 NMOS 트랜지스터 배열의 트랜스컨덕턴스도 조절하게 디자인하였다. 제안된 디지털 위상 동기 회로는 40-nm CMOS 공정으로 제작되었다. 0.06 mm2 의 면적을 차지하고 13.5 mW의 전력을 소모하며, 고안된 전원 잡음 흡수 회로는 각각 0.0017 mm2와 0.9mW, 즉, 전체의 6.6%와 2.8%만 차지하였다. 8GHz 동작에서, 제안된 회로는 1-MHz 40-mVpp 사인파 전원 잡음 아래에서 3.255 ps의 RMS 지터를 보였지만, 고안된 회로의 동작과 함께 1.268 ps로 줄었다.CHAPTER 1 INTRODUCTION 1 1.1 MOTIVATION 1 1.2 THESIS ORGANIZATION 4 CHAPTER 2 BACKGROUNDS 5 2.1 OVERVIEW 5 2.2 COMPOSITIONS OF THE ADPLL 8 2.2.1 TIME-TO-DIGITAL CONVERTER 8 2.2.2 DIGITAL LOOP FILTER 11 2.2.3 DIGITALLY CONTROLLED OSCILLATOR 14 2.2.4 PRIOR WORKS OF SUPPLY NOISE CANCELLATION 19 2.3 ADPLL LOOP ANALYSIS 21 2.3.1 LOOP TRANSFER FUNCTION 21 2.3.2 NOISE MODELING 23 CHAPTER 3 DESIGN OF SUPPLY NOISE-INSENSITIVE ADPLL 26 3.1 DESIGN CONSIDERATION 26 3.2 OVERALL ARCHITECTURE 28 3.3 PROPOSED CIRCUIT IMPLEMENTATION 30 3.3.1 PFD-TDC AND DIGITAL BLOCK 30 3.3.2 PROPOSED DCO WITH DCR 33 3.3.3 NMOS SHUNT REGULATOR ARRAY 37 3.3.4 SUPPLY SENSING AMPLIFIER 39 3.3.5 SUPPLY NOISE-INSENSITIVE TECHNIQUE 41 CHAPTER 4 MEASUREMENT RESULTS 43 4.1 CHIP PHOTOMICROGRAPH 43 4.2 MEASUREMENT SETUP 45 4.3 MEASUREMENT RESULTS 46 4.3.1 FREE-RUNNING DCO 46 4.3.2 CLOSED-LOOP PERFORMANCE 47 4.4 PERFORMANCE SUMMARY 49 CHAPTER 5 CONCLUSION 51 BIBLIOGRAPHY 52 초 록 55석

저 잡음 디지털 위상동기루프의 합성

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2014. 2. 정덕균.As a device scaling proceeds, Charge Pump PLL has been confronted by many design challenges. Especially, a leakage current in loop filter and reduced dynamic range due to a lower operating voltage make it difficult to adopt a conventional analog PLL architecture for a highly scaled technology. To solve these issues, All Digital PLL (ADPLL) has been widely studied recently. ADPLL mitigates a filter leakage and a reduced dynamic range issues by replacing the analog circuits with digital ones. However, it is still difficult to get a low jitter under low supply voltage. In this thesis, we propose a dual loop architecture to achieve a low jitter even with a low supply voltage. And bottom-up based multi-step TDC and DCO are proposed to meet both fine resolution and wide operation range. In the aspect of design methodology, ADPLL has relied on a full custom design method although ADPLL is fully described in HDL (Hardware Description Language). We propose a new cell based layout technique to automatically synthesize the whole circuit and layout. The test chip has no linearity degradation although it is fully synthesized using a commercially available auto P&R tool. We has implemented an all digital pixel clock generator using the proposed dual loop architecture and the cell based layout technique. The entire circuit is automatically synthesized using 28nm CMOS technology. And s-domain linear model is utilized to optimize the jitter of the dual-loop PLL. Test chip occupies 0.032mm2, and achieves a 15ps_rms integrated jitter although it has extremely low input reference clock of 100 kHz. The whole circuit operates at 1.0V and consumes only 3.1mW.Abstract i Lists of Figures vii Lists of Tables xiii 1. Introduction 1 1.1 Thesis Motivation and Organization 1 1.1.1 Motivation 1 1.1.2 Thesis Organization 2 1.2 PLL Design Issues in Scaled CMOS Technology 3 1.2.1 Low Supply Voltage 4 1.2.2 High Leakage Current 6 1.2.3 Device Reliability: NBTI, HCI, TDDB, EM 8 1.2.4 Mismatch due to Proximity Effects: WPE, STI 11 1.3 Overview of Clock Synthesizers 14 1.3.1 Dual Voltage Charge Pump PLL 14 1.3.2 DLL Based Edge Combining Clock Multiplier 16 1.3.3 Recirculation DLL 17 1.3.4 Reference Injected PLL 18 1.3.5 All Digital PLL 19 1.3.6 Flying Adder Clock Synthesizer 20 1.3.7 Dual Loop Hybrid PLL 21 1.3.8 Comparisons 23 2. Tutorial of ADPLL Design 25 2.1 Introduction 25 2.1.1 Motivation for a pure digital 25 2.1.2 Conversion to digital domain 26 2.2 Functional Blocks 26 2.2.1 TDC, and PFD/Charge Pump 26 2.2.2 Digital Loop Filter and Analog R/C Loop Filter 29 2.2.3 DCO and VCO 34 2.2.4 S-domain Model of the Whole Loop 34 2.2.5 ADPLL Loop Design Flow 36 2.3 S-domain Noise Model 41 2.3.1 Noise Transfer Functions 41 2.3.2 Quantization Noise due to Limited TDC Resolution 45 2.3.3 Quantization Noise due to Divider ΔΣ Noise 46 2.3.4 Quantization Noise due to Limited DCO Resolution 47 2.3.5 Quantization Noise due to DCO ΔΣ Dithering 48 2.3.6 Random Noise of DCO and Input Clock 50 2.3.7 Over-all Phase Noise 50 3. Synthesizable All Digital Pixel Clock PLL Design 53 3.1 Overview 53 3.1.1 Introduction of Pixel Clock PLL 53 3.1.1 Design Specifications 55 3.2 Proposed Architecture 60 3.2.1 All Digital Dual Loop PLL 60 3.2.2 2-step controlled TDC 61 3.2.3 3-step controlled DCO 64 3.2.4 Digital Loop Filter 76 3.3 S-domain Noise Model 78 3.4 Loop Parameter Optimization Based on the s-domain Model 85 3.5 RTL and Gate Level Circuit Design 88 3.5.1 Overview of the design flow 88 3.5.2 Behavioral Simulation and Gate level synthesis 89 3.5.1 Preventing a meta-stability 90 3.5.1 Reusable Coding Style 92 3.6 Layout Synthesis 94 3.6.1 Auto P&R 94 3.6.2 Design of Unit Cells 97 3.6.3 Linearity Degradation in Synthesized TDC 98 3.6.4 Linearity Degradation in Synthesized DCO 106 3.7 Experiment Results 109 3.7.1 DCO measurement 109 3.7.2 PLL measurement 113 3.8 Conclusions 117 A. Device Technology Scaling Trends 118 A.1. Motivation for Technology Scaling 118 A.2. Constant Field Scaling 120 A.3. Quasi Constant Voltage Scaling 123 A.4. Device Technology Trends in Real World 124 B. Spice Simulation Tip for a DCO 137 C. Phase Noise to Jitter Conversion 141 Bibliography 144 초록 151Docto