Event Driven Modeling and Characterization of the Second Order Voltage Switched Charge Pump PLL - Archive ouverte HAL
Article Dans Une Revue IEEE Transactions on Circuits and Systems I: Regular Papers Année : 2016

Event Driven Modeling and Characterization of the Second Order Voltage Switched Charge Pump PLL

Résumé

The charge pump phase locked loop (CP-PLL) is widely used subsystem in modern mixed-signal electronic systems that are utilized in digital and wireless applications such as clock generation, synchronization and frequency synthesis. In the classical mode, the combination of a current switched charge pump and a digital phase and frequency detector (CP-PFD) circuits produces an ideal pulse width modulated constant current during one sampling period, which permits a suitable transient performance. Nevertheless, many commercially used CP-PLL chips (e.g., 4046 family) have a voltage switched charge pump (VSCP) because the design of the constant voltage source is easier than the constant current generator and it is a low cost solution. However, the VSCP delivers a non-constant pump current, which varies during one sampling period related to the electrical load of the loop filter (LF). This effect results in a varying gain of the control system affecting significantly its tracking ability. Furthermore, due to its hybrid structure, the simulation of the CP-PLL at high frequencies is challenging and the analysis of its transient characteristics during its non-linear acquisition procedure is not easy. In this paper, a first ever exact and nonlinear model based on the phase equations of the second order voltage switched charge pump phase locked loop (VSCP-PLL) is established by using an event driven (ED) technique. This exact model is then simplified by using a step-wise quasi-constant current approximation during one sampling period to obtain the analytical phase equations. The derived ED-model is validated at transistor level simulations using 130 nm CMOS process. Furthermore, some typical nonlinear features of the VSCP-PLL are explored and the developed ED-models are compared with the quasi-time-continuous (QTC) theory.
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Dates et versions

hal-01815667 , version 1 (14-06-2018)

Identifiants

Citer

Ehsan Ali, Christian Hangmann, Christian Hedayat, Fayrouz. Haddad, Wenceslas Rahajandraibe, et al.. Event Driven Modeling and Characterization of the Second Order Voltage Switched Charge Pump PLL. IEEE Transactions on Circuits and Systems I: Regular Papers, 2016, 63 (3), pp.347 - 358. ⟨10.1109/TCSI.2015.2512759⟩. ⟨hal-01815667⟩
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