Title Page
Abstract
Contents
Chapter 1. Introduction 11
1.1. Motivation 11
1.2. Thesis Organization 14
Chapter 2. Background 16
2.1. Basic of Ring Oscillator 16
2.2. Phase Noise in Ring Oscillators 18
Chapter 3. Supply Noise Transfer Analysis 24
3.1. Impulse Sensitivity of Supply Voltage 24
3.2. The Effect of Supply Noise on Ring Oscillators 28
Chapter 4. Effect of LDO Output Noise to Phase Noise of Ring Oscillator 33
4.1. Necessity of Small-Sized, Capacitor-less LDO 33
4.2. Contribution of LDO Internal Noise to Phase Noise of Ring Oscillator 35
4.3. Proposed Figure of Merit 37
Chapter 5. Capacitor-less LDO Design and Optimization for Ring Oscillator 38
Chapter 6. Simulation Results 41
Chapter 7. Conclusion 49
Bibliography 50
초록 52
Table I. The simulated and calculated phase noises in the presence of white noises. 29
Table II. The performance comparison between nominal and optimized LDO. 47
Table III. The Performance of LDO3 and LDO4 48
Fig. 1.1. Trend of supply voltage scaling Vs. the effective transistor channel length 12
Fig. 2.1. The basic diagram of the ring oscillator. 17
Fig. 2.2. The basic diagram of the digitally controlled ring oscillator. 18
Fig. 2.3. Different phase shift behaviors, (a) and (b) by the impulse injection timing. 19
Fig. 2.4. The example waveform and ISF of the typical ring oscillator. 20
Fig. 2.5. The approximate waveform and ISF for the ring oscillator. 21
Fig. 2.6. The waveforms of the adjacent oscillation nodes showing the relationship between the rise/fall time and the delay time. 22
Fig. 2.7. The amplifier-like inverter stage of the ring oscillator at the common mode. 23
Fig. 3.1. Noise contribution protocols of (a) ring oscillator (internal noise source) and (b) supply noise (external noise source.) 25
Fig. 3.2. Simulation method of the impulse voltage injection to the supply node. 25
Fig. 3.3. The simulation to measure the amount of the phase shift when the current impulse pair is injected. 26
Fig. 3.4. The simulation to measure the amount of the phase shift when the supply voltage impulse is injected. 26
Fig. 3.5. The phase noise plot in the presence of white noises. 28
Fig. 3.6. The comparison of the ring oscillator and supply noises in terms of the thermal and flicker noises. 31
Fig. 4.1. The diagram of distributed, localized capacitor-less LDOs 34
Fig. 4.2. The basic LDO block diagram with noise transfer. 36
Fig. 4.3. Thevenin equivalent model of the ring oscillator. 36
Fig. 5.1. The LDO design framework for the optimization. 39
Fig. 5.2. The proposed self-biased LDO architecture. 39
Fig. 6.1. The overall configuration comprised of four LDO test blocks. 42
Fig. 6.2. The scheme to switch the (a) LDO and (b) ring oscillator. 42
Fig. 6.3. The layout of the proposed architecture. 43
Fig. 6.4. The die photograph of the implemented LDOs. 43
Fig. 6.5. The voltage reference output voltage according to supply voltage at three different process corners (TT, FF, SS.) 44
Fig. 6.6. The voltage reference output voltage according to the temperature at three different voltage corners (1.08 V, 1.2 V, 1.32 V). 45
Fig. 6.7. The output noise plot of LDO3 and LDO4. 45