A 1.35GHz All-Digital Fractional-N PLL with Adaptive Loop Gain Controller and Fractional Divider

A 1.35GHz all-digital phase-locked loop (ADPLL) with an adaptively controlled loop filter and a 1/3rd-resolution fractional divider is presented. The adaptive loop gain controller (ALGC) effectively reduces the nonlinear characteristics of the bang-bang phase-frequency detector (BBPFD). The fractional divider partially compensates for the input phase error which is caused by the fractional-N frequency synthesis operation. A prototype ADPLL using a BBPFD with a dead zone free retimer, an ALGC, and a fractional divider is fabricated in 0.13m CMOS. The core occupies 0.19mm2 and consumes 13.7mW from a 1.2V supply. The measured RMS jitter was 4.17ps at a 1.35GHz clock output

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

다이렉트 경로를 이용한 5/8GHz 듀얼 모드 All-Digital Phase-Locked Loop의 설계

학위논문 (석사)-- 서울대학교 대학원 : 공과대학 전기·정보공학부, 2019. 2. 정덕균.최근 데이터의 전송 속도가 비약적으로 증가함에 따라 데이터 처리 방식이 다양하게 연구되었고 여러 방식에 따른 고속의 송수신기 설계가 중요시되고 있다. 그 중에서도 Clock 신호를 합성하는 역할인 Phase-Locked Loop (PLL)에 대한 연구가 활발히 진행되고 있다. 특히 패시브 소자를 Loop Filter에 사용해야 하는 Analog PLL보다는 PVT 변화에 둔감하고 Programmable 하다는 장점을 가진 All Digital PLL (AD-PLL)에 대한 관심도가 높아지고 있다. 본 논문에서는 Peripheral Component Interconnect Express Memory interface (PCIe) 지원을 위한 32Gbps Serial Link에 Common Clock 신호를 제공하는 5/8 GHz 듀얼 모드 AD-PLL을 제안한다. 이전 세대와의 호환성을 위해 넓은 동작 영역을 갖고 모드 선택이 가능한 듀얼 모드 Digitally Controlled Oscillator (DCO)를 사용하였고 설계 전 Digital 방식으로 변환함에 따라 발생하는 Quantization Noise에 대해 분석하고 Matlab, Verilog Behavioral Simulation을 통해 출력의 Phase Noise와 RMS Jitter 값을 예측해 볼 수 있었다. 또한 Reference Clock의 한 주기 이내에 정보가 Update되지 못하는 Loop Delay의 문제를 해결하기 위해 Digital Loop Filter (DLF)의 처리 과정을 거치지 않고 Time to Digital Converter (TDC)의 출력을 DCO에 바로 전달해 줄 수 있는 다이렉트 경로를 제안하였다. 설계된 회로는 TSMC 사의 65nm 공정으로 구현되었고 AD-PLL의 전체 유효 면적은 Decoupling Cap을 제외하고 420um·300um이며 측정된 출력 Clock 신호의 RMS Jitter값은 8GHz 모드에서 357fs, 5GHz 모드에서 394fs이다. AD-PLL의 동작 주파수는 PCIe Spec의 다양한 모드를 지원하기 위해 외부의 입력 모드 신호에 따라서 5GHz/8GHz의 High/Low Band를 지원하고 1.2V의 공급 전압에서 Repeater를 제외하고 8GHz 모드에서는 총 18.26mW, 5GHz 모드에서는 총 12.06mW의 Power를 소비한다.As data transmission speed has increased in recent years, a variety of data processing techniques have been studied and high-speed transceiver has become important. Above all, Phase-Locked Loop (PLL), which synthesizes high frequency clock signal, is one of the important parts. In particular, All-Digital PLL(AD-PLL), which has advantage of programmability and PVT tolerance, is replacing Analog PLL that requires passive element utilization. This thesis presents a 5/8GHz dual mode AD-PLL to provide common clock signal to 32Gbps serial link to support Peripheral Component Interconnect Express(PCIe) PHY. For compatibility with previous generations and wide operating region, AD-PLL uses dual mode Digitally Controlled Oscillator(DCO). Before an actual design, output RMS Jitter, Phase Noise of AD-PLL and quantization error resulting from digital conversion are calculated and analyzed by using Matlab, Verilog behavioral simulation in a short time. In addition, the output of Time-to-Digital Converter(TDC) is directly delivered to the DCO without Digital Loop Filter(DLF) using direct path to solve loop delay issue where information cant be updated within a cycle of reference clock. The proposed AD-PLL is fabricated in 65nm CMOS process and effective area of AD-PLL is 420um·300um and the measured RMS Jitter is 357fs at 8GHz mode, 394fs at 5GHz mode. Also, proposed AD-PLL supports the low/high band(5/8GHz) to be compatible with the various modes of PCIe spec. Power dissipation is 18.26mW at 8GHz mode, 12.06mW at 5GHz mode in 1.2V supply voltage domain excluding repeater.제 1 장 서 론 1 1.1 연구의 배경 1 1.2 논문의 구성 3 제 2 장 Basics of AD-PLL 4 2.1 Introduction of AD-PLL 4 2.2 Building Blocks of AD-PLL 5 2.2.1 Time to Digital Converter 6 2.2.2 Digital Loop Filter 8 2.2.3 Digitally Controlled Oscillator 10 2.3 Phase Noise Analysis 13 2.4 Loop Delay 18 제 3 장 Design of AD-PLL 22 3.1 Design Consideration 22 3.2 Overall Architecture 22 3.3 Phase Frequency Detectable TDC 24 3.4 Digital Loop Filter 27 3.5 Digitally Controlled Oscillator 30 3.6 Direct Path 33 3.7 Level Shifter and Divider 36 3.8 Clock Tree 39 제 4 장 Measurement and Simulation Results 41 4.1 Measurement Setup 41 4.2 Die Photomicrograph 43 4.3 Frequency Tracking Behavior 44 4.4 Clock Distribution 46 4.5 Phase Noise and Spur 47 4.6 Performance Summary 53 제 5 장 Conclusion 55 참고 문헌 56 Abstract 59Maste

통계적 주파수 검출기 기반 기준 주파수를 사용하지 않는 클록 및 데이터 복원 회로의 설계 방법론

학위논문(박사) -- 서울대학교대학원 : 공과대학 전기·정보공학부, 2022. 8. 정덕균.In this thesis, a design of a high-speed, power-efficient, wide-range clock and data recovery (CDR) without a reference clock is proposed. A frequency acquisition scheme using a stochastic frequency detector (SFD) based on the Alexander phase detector (PD) is utilized for the referenceless operation. Pat-tern histogram analysis is presented to analyze the frequency acquisition behavior of the SFD and verified by simulation. Based on the information obtained by pattern histogram analysis, SFD using autocovariance is proposed. With a direct-proportional path and a digital integral path, the proposed referenceless CDR achieves frequency lock at all measurable conditions, and the measured frequency acquisition time is within 7μs. The prototype chip has been fabricated in a 40-nm CMOS process and occupies an active area of 0.032 mm2. The proposed referenceless CDR achieves the BER of less than 10-12 at 32 Gb/s and exhibits an energy efficiency of 1.15 pJ/b at 32 Gb/s with a 1.0 V supply.본 논문은 기준 클럭이 없는 고속, 저전력, 광대역으로 동작하는 클럭 및 데이터 복원회로의 설계를 제안한다. 기준 클럭이 없는 동작을 위해서 알렉산더 위상 검출기에 기반한 통계적 주파수 검출기를 사용하는 주파수 획득 방식이 사용된다. 통계적 주파수 검출기의 주파수 추적 양상을 분석하기 위해 패턴 히스토그램 분석 방법론을 제시하였고 시뮬레이션을 통해 검증하였다. 패턴 히스토그램 분석을 통해 얻은 정보를 바탕으로 자기공분산을 이용한 통계적 주파수 검출기를 제안한다. 직접 비례 경로와 디지털 적분 경로를 통해 제안된 기준 클럭이 없는 클럭 및 데이터 복원회로는 모든 측정 가능한 조건에서 주파수 잠금을 달성하는 데 성공하였고, 모든 경우에서 측정된 주파수 추적 시간은 7μs 이내이다. 40-nm CMOS 공정을 이용하여 만들어진 칩은 0.032 mm2의 면적을 차지한다. 제안하는 클럭 및 데이터 복원회로는 32 Gb/s의 속도에서 비트에러율 10-12 이하로 동작하였고, 에너지 효율은 32Gb/s의 속도에서 1.0V 공급전압을 사용하여 1.15 pJ/b을 달성하였다.CHAPTER 1 INTRODUCTION 1 1.1 MOTIVATION 1 1.2 THESIS ORGANIZATION 13 CHAPTER 2 BACKGROUNDS 14 2.1 CLOCKING ARCHITECTURES IN SERIAL LINK INTERFACE 14 2.2 GENERAL CONSIDERATIONS FOR CLOCK AND DATA RECOVERY 24 2.2.1 OVERVIEW 24 2.2.2 JITTER 26 2.2.3 CDR JITTER CHARACTERISTICS 33 2.3 CDR ARCHITECTURES 39 2.3.1 PLL-BASED CDR – WITH EXTERNAL REFERENCE CLOCK 39 2.3.2 DLL/PI-BASED CDR 44 2.3.3 PLL-BASED CDR – WITHOUT EXTERNAL REFERENCE CLOCK 47 2.4 FREQUENCY ACQUISITION SCHEME 50 2.4.1 TYPICAL FREQUENCY DETECTORS 50 2.4.1.1 DIGITAL QUADRICORRELATOR FREQUENCY DETECTOR 50 2.4.1.2 ROTATIONAL FREQUENCY DETECTOR 54 2.4.2 PRIOR WORKS 56 CHAPTER 3 DESIGN OF THE REFERENCELESS CDR USING SFD 58 3.1 OVERVIEW 58 3.2 PROPOSED FREQUENCY DETECTOR 62 3.2.1 MOTIVATION 62 3.2.2 PATTERN HISTOGRAM ANALYSIS 68 3.2.3 INTRODUCTION OF AUTOCOVARIANCE TO STOCHASTIC FREQUENCY DETECTOR 75 3.3 CIRCUIT IMPLEMENTATION 83 3.3.1 IMPLEMENTATION OF THE PROPOSED REFERENCELESS CDR 83 3.3.2 CONTINUOUS-TIME LINEAR EQUALIZER (CTLE) 85 3.3.3 DIGITALLY-CONTROLLED OSCILLATOR (DCO) 87 3.4 MEASUREMENT RESULTS 89 CHAPTER 4 CONCLUSION 99 APPENDIX A DETAILED FREQUENCY ACQUISITION WAVEFORMS OF THE PROPOSED SFD 100 BIBLIOGRAPHY 108 초 록 122박

적응형 눈 감지 방법을 포함한 저전력 메모리 컨트롤러의 설계

학위논문 (박사)-- 서울대학교 대학원 공과대학 전기·컴퓨터공학부, 2017. 8. 김수환.and the read margin was enhanced from 0.30UI and 76mV without AF-CTLE to 0.47UI and 80mV to with AF-CTLE. The power efficiency during burst write and read were 5.68pJ/bit and 1.83pJ/bit respectively.A 4266Mb/s/pin LPDDR4 memory controller with an asynchronous feedback continuous-time linear equalizer and an adaptive 3-step eye detection algorithm is presented. The asynchronous feedback continuous-time linear equalizer removes the glitch of DQS without training by applying an offset larger than the noise, and improves read margin by operating as a decision feedback equalizer in DQ path. The adaptive 3-step eye detection algorithm reduces power consumption and black-out time in initialization sequence and retraining in comparison to the 2-dimensional full scanning. In addition, the adaptive 3-step eye detection algorithm can maintain the accuracy by sequentially searching the eye boundaries and initializing the resolution using the binary search method when the eye detection result changes. To achieve high bandwidth, a transmitter and receiver suitable for training are proposed. The transmitter consists of a phase interpolator, a digitally-controlled delay line, a 16:1 serializer, a pre-driver and low-voltage swing terminated logic. The receiver consists of a reference voltage generator, a continuous-time linear equalizer, a phase interpolator, a digitally-controlled delay line, a 1:4 deserializer, and a 4:16 deserializer. The clocking architecture is also designed for low power consumption in idle periods, which are commonly lengthy in mobile applications. A prototype chip was implemented in a 65nm CMOS process with ball grid array package and tested with commodity LPDDR4. The write margin was 0.36UI and 148mVCHAPTER 1 INTRODUCTION 1 1.1 MOTIVATION 1 1.2 THESIS ORGANIZATION 5 CHAPTER 2 LPDDR4 6 2.1 COMPARISON BETWEEN LPDDR3 AND LPDDR4 6 2.2 SOURCE SYNCHRONOUS CLOCKING SCHEME 9 2.3 SIGNALING STANDARDS 11 2.4 MULTIPLE TRAININGS 14 2.5 RE-TRAINING AND RE-INITIALIZATION 16 CHAPTER 3 ADAPTIVE EYE DETECTION 18 3.1 EYE DETECTION 18 3.2 1X2Y3X EYE DETECTION 20 3.3 ADAPTIVE GAIN CONTROL 22 3.4 ADAPTIVE 1X2Y3X EYE DETECTION 24 CHAPTER 4 LPDDR4 MEMORY CONTROLLER 26 4.1 DESIGN PROCEDURE 26 4.2 ARCHITECTURE 30 4.2.1 TRANSMITTER 33 4.2.2 RECEIVER 35 4.2.3 CLOCKING ARCHITECTURE 38 4.3 CIRCUIT IMPLEMENTATION 43 4.3.1 ADPLL WITH MULTI-MODULUS DIVIDER 43 4.3.2 ADDLL WITH TRIANGULAR-MODULATED PI 45 4.3.3 CTLE WITH AUTO-DQS CLEANING 47 4.3.4 DES WITH CLOCK DOMAIN CROSSING 52 4.3.5 LVSTL WITH ZQ CALIBRATION 54 4.3.6 COARSE-FINE DCDL 56 4.4 LINK TRAINING 57 4.4.1 SIMULATION RESULTS 59 CHAPTER 5 MEASUREMENT RESULTS 72 5.1 MEASUREMENT SETUP 72 5.2 MEASUREMENT RESULTS OF SUB-BLOCK 80 5.2.1 ADPLL WITH MULTI-MODULUS DIVIDER 80 5.2.2 ADDLL WITH TRIANGULAR-MODULATED PI 82 5.2.3 COARSE-FINE DCDL 84 5.3 LPDDR4 INTERFACE MEASUREMENT RESULTS 84 CHAPTER 6 CONCLUSION 88 BIBLIOGRAPHY 90Docto

A 10Gb/s Full On-chip Bang-Bang Clock and Data Recovery System Using an Adaptive Loop Bandwidth Strategy

As demand for higher bandwidth I/O grows, the front end design of serial link becomes significant to overcome stringent timing requirements on noisy and bandwidthlimited channels. As a clock reconstructing module in a receiver, the recovered clock quality of Clock and Data Recovery is the main issue of the receiver performance. However, from unknown incoming jitter, it is difficult to optimize loop dynamics to minimize steady-state and dynamic jitter. In this thesis a 10 Gb/s adaptive loop bandwidth clock and data recovery circuit with on-chip loop filter is presented. The proposed system optimizes the loop bandwidth adaptively to minimize jitter so that it leads to an improved jitter tolerance performance. This architecture tunes the loop bandwidth by a factor of eight based on the phase information of incoming data. The resulting architecture performs as good as a maximum fixed loop bandwidth CDR while tracking high speed input jitter and as good as a minimum fixed bandwidth CDR while suppressing wide bandwidth steady-state jitter. By employing a mixed mode predictor, high updating rate loop bandwidth adaptation is achieved with low power consumption. Another relevant feature is that it integrates a typically large off-chip filter using a capacitance multiplication technique that employs dual charge pumps. The functionality of the proposed architecture has been verified through schematic and behavioral model simulations. In the simulation, the performance of jitter tolerance is confirmed that the proposed solution provides improved results and robustness to the variation of jitter profile. Its applicability to industrial standards is also verified by the jitter tolerance passing SONET OC-192 successfully

올 디지털 클럭 및 데이터 복원 회로를 적용한 고속 광 수신기 설계

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2016. 8. 정덕균.This thesis presents a 22- to 26.5-Gb/s optical receiver with an all-digital clock and data recovery (ADCDR) fabricated in a 65-nm CMOS process. The receiver consists of an optical front-end and a half-rate bang-bang clock and data recovery circuit. The optical front-end achieves low power consumption by using inverter-based amplifiers and realizes sufficient bandwidth by applying several bandwidth extension techniques. In addition, in order to minimize additional jitter at the front-end, not only magnitude and bandwidth but also phase delay responses are considered. The ADCDR employs an LC quadrature digitally-controlled oscillator (LC-QDCO) to achieve a high phase noise figure-of-merit at tens of gigahertz. The recovered clock jitter is 1.28 psrms and the measured jitter tolerance exceeds the tolerance mask specified in IEEE 802.3ba. The receiver sensitivity is 106 and 184 μApk-pk for a bit error rate of 10−12 at data rates of 25 and 26.5 Gb/s, respectively. The entire receiver chip occupies an active die area of 0.75 mm2 and consumes 254 mW at a data rate of 26.5 Gb/s. The energy efficiencies of the front-end and entire receiver at 26.5 Gb/s are 1.35 and 9.58 pJ/bit, respectively.CHAPTER 1 INTRODUCTION 1 1.1 MOTIVATION 1 1.2 THESIS ORGANIZATION 5 CHAPTER 2 DESIGN OF OPTICAL FRONT-END 7 2.1 OVERVIEW 7 2.2 BACKGROUND ON OPTICAL FRONT-END 9 2.2.1 PHOTODIODE 9 2.2.2 TRANSIMPEDANCE AMPLIFIER 11 2.2.3 POST AMPLIFIER 17 2.2.4 SHUNT INDUCTIVE PEAKING 25 2.3 CIRCUIT IMPLEMENTATION 29 2.3.1 OVERALL ARCHITECTURE 29 2.3.2 TRANSIMPEDANCE AMPLIFIER 31 2.3.3 POST AMPLIFIER 34 2.4 NOISE ANALYSIS 43 2.4.1 PHOTODIODE 43 2.4.2 OPTICAL FRONT-END 44 2.4.3 SENSITIVITY 46 CHAPTER 3 DESIGN OF ADCDR FOR OPTICAL RECEIVER 48 3.1 OVERVIEW 48 3.2 BACKGROUND ON PLL-BASED ADCDR 51 3.2.1 PHASE DETECTOR 51 3.2.2 DIGITAL LOOP FILTER 54 3.2.3 DIGITALLY-CONTROLLED OSCILLATOR 56 3.2.4 ANALYSIS OF BANG-BANG ADCDR 67 3.3 CIRCUIT IMPLEMENTATION 70 3.3.1 OVERALL ARCHITECTURE 70 3.3.2 PHASE DETECTION LOGIC 75 3.3.3 DIGITAL LOOP FILTER 77 3.3.4 LC QUADRATURE DCO 78 CHAPTER 4 EXPERIMENTAL RESULTS 82 CHAPTER 5 CONCLUSION 90 BIBLIOGRAPHY 92 초록 101Docto

고속 시리얼 링크를 위한 고리 발진기를 기반으로 하는 주파수 합성기

학위논문(박사) -- 서울대학교대학원 : 공과대학 전기·정보공학부, 2022. 8. 정덕균.In this dissertation, major concerns in the clocking of modern serial links are discussed. As sub-rate, multi-standard architectures are becoming predominant, the conventional clocking methodology seems to necessitate innovation in terms of low-cost implementation. Frequency synthesis with active, inductor-less oscillators replacing LC counterparts are reviewed, and solutions for two major drawbacks are proposed. Each solution is verified by prototype chip design, giving a possibility that the inductor-less oscillator may become a proper candidate for future high-speed serial links. To mitigate the high flicker noise of a high-frequency ring oscillator (RO), a reference multiplication technique that effectively extends the bandwidth of the following all-digital phase-locked loop (ADPLL) is proposed. The technique avoids any jitter accumulation, generating a clean mid-frequency clock, overall achieving high jitter performance in conjunction with the ADPLL. Timing constraint for the proper reference multiplication is first analyzed to determine the calibration points that may correct the existent phase errors. The weight for each calibration point is updated by the proposed a priori probability-based least-mean-square (LMS) algorithm. To minimize the time required for the calibration, each gain for the weight update is adaptively varied by deducing a posteriori which error source dominates the others. The prototype chip is fabricated in a 40-nm CMOS technology, and its measurement results verify the low-jitter, high-frequency clock generation with fast calibration settling. The presented work achieves an rms jitter of 177/223 fs at 8/16-GHz output, consuming 12.1/17-mW power. As the second embodiment, an RO-based ADPLL with an analog technique that addresses the high supply sensitivity of the RO is presented. Unlike prior arts, the circuit for the proposed technique does not extort the RO voltage headroom, allowing high-frequency oscillation. Further, the performance given from the technique is robust over process, voltage, and temperature (PVT) variations, avoiding the use of additional calibration hardware. Lastly, a comprehensive analysis of phase noise contribution is conducted for the overall ADPLL, followed by circuit optimizations, to retain the low-jitter output. Implemented in a 40-nm CMOS technology, the frequency synthesizer achieves an rms jitter of 289 fs at 8 GHz output without any injected supply noise. Under a 20-mVrms white supply noise, the ADPLL suppresses supply-noise-induced jitter by -23.8 dB.본 논문은 현대 시리얼 링크의 클락킹에 관여되는 주요한 문제들에 대하여 기술한다. 준속도, 다중 표준 구조들이 채택되고 있는 추세에 따라, 기존의 클라킹 방법은 낮은 비용의 구현의 관점에서 새로운 혁신을 필요로 한다. LC 공진기를 대신하여 능동 소자 발진기를 사용한 주파수 합성에 대하여 알아보고, 이에 발생하는 두가지 주요 문제점과 각각에 대한 해결 방안을 탐색한다. 각 제안 방법을 프로토타입 칩을 통해 그 효용성을 검증하고, 이어서 능동 소자 발진기가 미래의 고속 시리얼 링크의 클락킹에 사용될 가능성에 대해 검토한다. 첫번째 시연으로써, 고주파 고리 발진기의 높은 플리커 잡음을 완화시키기 위해 기준 신호를 배수화하여 뒷단의 위상 고정 루프의 대역폭을 효과적으로 극대화 시키는 회로 기술을 제안한다. 본 기술은 지터를 누적 시키지 않으며 따라서 깨끗한 중간 주파수 클락을 생성시켜 위상 고정 루프와 함께 높은 성능의 고주파 클락을 합성한다. 기준 신호를 성공적으로 배수화하기 위한 타이밍 조건들을 먼저 분석하여 타이밍 오류를 제거하기 위한 방법론을 파악한다. 각 교정 중량은 연역적 확률을 기반으로한 LMS 알고리즘을 통해 갱신되도록 설계된다. 교정에 필요한 시간을 최소화 하기 위하여, 각 교정 이득은 타이밍 오류 근원들의 크기를 귀납적으로 추론한 값을 바탕으로 지속적으로 제어된다. 40-nm CMOS 공정으로 구현된 프로토타입 칩의 측정을 통해 저소음, 고주파 클락을 빠른 교정 시간안에 합성해 냄을 확인하였다. 이는 177/223 fs의 rms 지터를 가지는 8/16 GHz의 클락을 출력한다. 두번째 시연으로써, 고리 발진기의 높은 전원 노이즈 의존성을 완화시키는 기술이 포함된 주파수 합성기가 설계되었다. 이는 고리 발진기의 전압 헤드룸을 보존함으로서 고주파 발진을 가능하게 한다. 나아가, 전원 노이즈 감소 성능은 공정, 전압, 온도 변동에 대하여 민감하지 않으며, 따라서 추가적인 교정 회로를 필요로 하지 않는다. 마지막으로, 위상 노이즈에 대한 포괄적 분석과 회로 최적화를 통하여 주파수 합성기의 저잡음 출력을 방해하지 않는 방법을 고안하였다. 해당 프로토타입 칩은 40-nm CMOS 공정으로 구현되었으며, 전원 노이즈가 인가되지 않은 상태에서 289 fs의 rms 지터를 가지는 8 GHz의 클락을 출력한다. 또한, 20 mVrms의 전원 노이즈가 인가되었을 때에 유도되는 지터의 양을 -23.8 dB 만큼 줄이는 것을 확인하였다.1 Introduction 1 1.1 Motivation 3 1.1.1 Clocking in High-Speed Serial Links 4 1.1.2 Multi-Phase, High-Frequency Clock Conversion 8 1.2 Dissertation Objectives 10 2 RO-Based High-Frequency Synthesis 12 2.1 Phase-Locked Loop Fundamentals 12 2.2 Toward All-Digital Regime 15 2.3 RO Design Challenges 21 2.3.1 Oscillator Phase Noise 21 2.3.2 Challenge 1: High Flicker Noise 23 2.3.3 Challenge 2: High Supply Noise Sensitivity 26 3 Filtering RO Noise 28 3.1 Introduction 28 3.2 Proposed Reference Octupler 34 3.2.1 Delay Constraint 34 3.2.2 Phase Error Calibration 38 3.2.3 Circuit Implementation 51 3.3 IL-ADPLL Implementation 55 3.4 Measurement Results 59 3.5 Summary 63 4 RO Supply Noise Compensation 69 4.1 Introduction 69 4.2 Proposed Analog Closed Loop for Supply Noise Compensation 72 4.2.1 Circuit Implementation 73 4.2.2 Frequency-Domain Analysis 76 4.2.3 Circuit Optimization 81 4.3 ADPLL Implementation 87 4.4 Measurement Results 90 4.5 Summary 98 5 Conclusions 99 A Notes on the 8REF 102 B Notes on the ACSC 105박

A LPDDR4 MEMORY CONTROLLER DESIGN WITH EYE CENTER DETECTION ALGORITHM

학위논문 (박사)-- 서울대학교 대학원 : 전기·컴퓨터공학부, 2016. 2. 김수환.The demand for higher bandwidth with reduced power consumption in mobile memory is increasing. In this thesis, architecture of the LPDDR4 memory controller, operated with a LPDDR4 memory, is proposed and designed, and efficient training algorithm, which is appropriate for this architecture, is proposed for memory training and verification. The operation speed range of the LPDDR4 memory specification is from 533Mbps to 4266Mbps, and the LPDDR4 memory controller is designed to support that range of the LPDDR4 memory. The phase-locked loop in the LPDDR4 memory controller is designed to operate between 1333MHz and 2133MHz. To cover the range of the LPDDR4 memory, the selectable frequency divider is used to provide operation clock. The output frequency of the phase-locked loop with divider is from 266MHz to 2133MHz. The delay-locked loop in the LPDDR4 memory controller is designed to operate between 266MHz and 2133MHz with 180˚ phase locking. The delay-locked loop is used each training operation, which is command training, data read and write training. To complete training in each training stage, eye center detection algorithm is used. The circuits for the proposed eye center detection algorithm such as delay line, phase interpolator and reference generator are designed and validated. The proposed 1x2y3x eye center detection algorithm is 23 times faster than conventional two-dimensional eye center detection algorithm and it can be implemented simply. Using 65nm CMOS process, the proposed LPDDR4 memory controller occupies 12mm2. The verification of the LPDDR4 memory controller is performed with commodity LPDDR4 memory. The verification of all training sequence, which is power on, initializing, boot up, command training, write leveling, read training, write training, is performed in this environment. The low voltage swing terminated logic driver and other several functions, including write leveling and data transmission, are verified at 4266Mbps and the entire LPDDR4 memory controller operations from 566Mbps to 1600Mbps are verified. The proposed eye center detection algorithm is verified from 566Mbps to 2843Mbps.CHAPTER 1 INTRODUCTION 1 1.1 MOTIVATION 1 1.2 INTRODUCTION 5 1.3 THESIS ORGANIZATION 7 CHAPTER 2 LPDDR4 MEMORY CONTROLLER DESIGN 8 2.1 DIFFERENCE BETWEEN LPDDR3 AND LPDDR4 MEMORY 8 2.1.1 ARCHITECTURAL DIFFERENCE BETWEEN LPDDR3 AND LPDDR4 MEMORY 10 2.1.2 SOURCE SYNCHRONOUS MATCHED SCHEME AND UNMATCHED SCHEME 11 2.1.3 LOW VOLTAGE SWING TERMINATED LOGIC DRIVER AND TERMINATION SCHEME 12 2.2 LPDDR4 MEMORY CONTROLLER SPECIFICATION 15 2.3 DESIGN PROCEDURE 18 CHAPTER 3 LPDDR4 MEMORY CONTROLLER ARCHITECTURE BASED ON MEMORY TRAINING 20 3.1 LPDDR4 MEMORY TRAINING SEQUENCE 20 3.2 LPDDR4 MEMORY TRAINING EYE DETECTION ALGORITHM 24 3.2.1 EYE CENTER DETECTION 24 3.2.2 1X2Y3X EYE CENTER DETECTION ALGORITHM 27 3.3. LPDDR4 MEMORY CONTROLLER DESIGN BASED ON MEMORY TRAINING 31 3.3.1 ARCHITECTURE FOR MEMORY BOOT UP AND POWER UP 31 3.3.2 CLOCK PATH ARCHITECTURE AND CLOCK TREE 34 3.3.3 COMMAND TRAINING AND COMMAND PATH ARCHITECTURE 35 3.3.4 WRITE LEVELING AND DATA STROBE TRANSMISSION PATH ARCHITECTURE 39 3.3.5 READ TRAINING AND READ PATH ARCHITECTURE 41 3.3.6 WRITE TRAINING AND WRITE PATH ARCHITECTURE 43 3.3.7 NORMAL READ/WRITE OPERATION AND MARGIN TEST 46 CHAPTER 4 LPDDR4 MEMORY CONTROLLER ARCHITECTURE MODELING AND CIRCUIT DESIGN 48 4.1 OVERALL LPDDR4 MEMORY CONTROLLER ARCHITECTURE MODELING 48 4.2 SIMULATION RESULT OF LPDDR4 MEMORY CONTROLLER MODELING 51 4.3 LPDDR4 MEMORY CONTROLLER CIRCUIT DESIGN 61 4.3.1 PHASE-LOCKED LOOP 61 4.3.2 DELAY-LOCKED LOOP 65 4.3.3 TRANSMITTER OF LPDDR4 MEMORY CONTROLLER: WRITE PATH 70 4.3.4 DE-SERIALIZER WITH CLOCK DOMAIN CROSSING 75 CHAPTER 5 MEASUREMENT RESULT OF LPDDR4 MEMORY CONTROLLER 77 5.1 LPDDR4 MEMORY CONTROLLER MEASUREMENT SETUP 77 5.1.1 LPDDR4 MEMORY CONTROLLER FLOOR PLAN AND LAYOUT 77 5.1.2 PACKAGE AND TEST BOARD 79 5.2 LPDDR4 MEMORY CONTROLLER SUB-BLOCK MEASUREMENT 81 5.2.1 PHASE-LOCKED LOOP 81 5.2.2 DELAY-LOCKED LOOP 83 5.2.3 200PS AND 800PS DELAY LINE 85 5.2.4 VOLTAGE REFERENCE GENERATOR 86 5.2.5 PHASE INTERPOLATOR 87 5.3 LPDDR4 MEMORY SYSTEM OPERATION MEASUREMENT 90 CHAPTER 6 CONCLUSION 93 APPENDIX OPERATION FLOW CHART OF THE PROPOSED LPDDR4 MEMORY CONTROLLER 95 BIBLIOGRAPHY 118 KOREAN ABSTRACT 124Docto