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This project presentation focuses on the CMOS implementation of a 3-stage ring oscillator phase locked loop for high-speed applications, including detailed simulations and power consumption analysis. The key components, such as phase detector, charge pump, and loop filter, are discussed along with future work suggestions.
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VLSI Project Presentation CMOS Phase Locked Loop Group Members: Louis and Yucong
Ring Oscillator CMOS ring oscillator requires odd number of inverters in series to introduce a feedback that cause output switching between 0 and 1.
CMOS Implementation for 3-stage ring oscillator starved current source
Transient Simulation of Ring Oscillator Control Voltage = 900mV, Frequency = 22.2GHz
Frequency Phase Detector CMOS implementation for high speed applications. It has free dead zone and more sensitive behavior.
Charge Pump and Loop Filter • Size PMOS and NMOS same to ensure identical current. • Use high order loop filter to stabilize charging/discharging response time.
PLL with Frequency Division 1/64 Division Simulations show ring oscillator works around 2GHz, we select 1/64 of 2GHz to be the reference, and simulate to prove functionality. 37 Stage Ring Oscillator
Power Consumption The ring oscillator consumes the most power because it is constantly switching. The current to the ring oscillator was on the order of 0.4mA so the power is about 0.4mW. The charge pump consumed the second most amount of power. When the ring oscillator starts locking to reference signal, it consumes lots of power because of DC current flowing. As the signal is locked, charge pump will mainly off and it will not consume lots of power. The PFD and frequency divider consumed the least amount of power (~0.05mW).
Errors and Future Work Locking time grows significantly when the size of ring oscillator and feedback loop is growing. Need longer simulation time Implement 1/N Frequency Divider where N is not 2^n
Reference [1] http://www.cse.unt.edu/~smohanty/Projects/DUE_0942629/Fall2011_ATV07_PLL-Design.pdf - Overview of Phase Locked Loops from a VLSI Perspective [2] http://dspace.mit.edu/bitstream/handle/1721.1/33386/62559899-MIT.pdf?sequence=2 - PhD Thesis on Phase Locked Ring Oscillator for Wireless Applications [3] http://www.ijsce.org/attachments/File/v2i2/B0529042212.pdf - Paper on Phase Frequency Detector and Charge Pump Design