Autonomous Event Driven Model of Second Order Voltage Switched Charge Pump PLL

The charge-pump Phase-Locked Loop (CP-PLL) is a widely used subsystem in wireless communication and smart system applications to perform the function of frequency synthesizer. Since the CP-PLL is a mixed-signal system, it is more complex to analyze the system behavior, especially when a voltage switched charge-pump-PLL (VSCP-PLL) is used. A more robust approach is required for such a non-linear pulse width modulated system, where the overall gain of the loop is varying due to non-constant pump current. To analyze the sampled behavior of a VSCP-PLL, the Event Driven (ED) model based on discrete-time phase equations is one of the powerful and resource efficient tool. In this brief, an autonomous ED model (time-independent and linear to fixed point) is developed for a second order VSCP-PLL by modifying the ED approach. The developed Autonomous ED-model is validated using the ED simulations in the locked state.