
- PLL Concept
- Type-I PLL
- PLL Tracking Characteristics
- PLL Circuit Components
+ Memoryless Phase Detectors
- Type-II PLL
+ Phase Detectors with Memory (PFD)
- Charge-Pump PLL (CP-PLL)
+ Dynamics of a Charge-Pump PLL
+ Non-Linearity of the CP-PLL
+ Non-idealities of CP-PLL
- Jitter and Phase Noise in PLL
- Delay-Locked Loops
- PLL Applications
- An introduction to the phase-locked loop (PLL) from a historical perspective
- General applications of PLL
- PLL concept
- Study of PLL locking by looking at the time-domain waveforms at the outputs of the phase- detector, low-pass filter, and voltage-controlled oscillator
- Derivation of the transfer function of type-I PLL
- Adding a zero to the loop filter to improve the stability of PLL
- Study of phase detector
+ Memoryless phase detectors
+ Phase detectors with memory
- Study of memoryless or switch phase detector
- A thorough large-signal analysis of the analog multiplier acting as a phase detector
- Investigating two approaches to analyze the multiplier as phase detector
1. Modeling the switch transistors by a switch function and derive the output with respect to the input voltages
2. Using the I-V relationship of a differential pair to derive the output voltage with respect to the input voltages.
- Revisiting the analog multiplier when the inputs are periodic square waves
- Investigating XOR as a phase detector
- An introduction to type-II PLL
- The need for frequency as well as phase detection mechanisms to improve the acquisition process of the PLL
- Introducing the phase-frequency detector (PFD)
- Using the state diagram to realize the PFD
- Introducing the charge-pump PLL
- Discussing why the loop gain of the phase-frequency detector/charge-pump/lowpass filter has infinite gain
- Investigating the issue of simultaneous narrow pulses appearing at both outputs of the PFD and its root
This course focuses on the study and design of phase-locked loops and the concept of phase-locking. We will learn that a phase-locked loop is essentially a closed-loop system that tracks an external periodic signal. A phase detector detects the phase difference between the reference and the signal coming from the oscillator within the loop. This phase difference is then extracted by a lowpass filter (LPF). The LPF output then controls the oscillation frequency of a voltage-controlled oscillator (VCO) in a way that in the steady state, the VCO output frequency is exactly equal to that of the input. In practice, a frequency divider chain is inserted between the VCO and the phase detector input to realize a closed-loop frequency multiplier. We will learn about the tracking characteristics of a PLL, and will see that the capture (acquisition) process is a nonlinear phenomenon. The course then digs deep into the phase detector implementation, followed by the concept of the phase-frequency detector. This will lay the groundwork for type-II PLL. We will specifically study a widely used type-II PLL, called charge-pump PLL. We will study the dynamic behavior of the charge-pump PLL and derive the PLL transfer function. We will learn that due to non-idealities, frequency fluctuation will appear at the output of the charpe-pump PLL . We will go through the issues due to these non-idealities and present some problems. The VCO phase noise and the noise coming from the input reference degrade the PLL output phase noise. We will study the impact of these sources of noise on the PLL phase noise. The course will then go through the concept of the delay-locked loop (DLL) and its applications. The course will finally discuss applications of the phase-locked loop. We will see the frequency synthesis in many electronic circuits will be realized by a PLL. We will see that PLL can effectively be used to realize a powerful skew reduction technique.