en 2-Integrated Circuits: Digital, Analog Integrated Circuits: Digital, Analog Research Paper Research Paper Due to the nonlinear nature of the Bang-Bang phase-locked loops (BBPLLs), its transient analysis is very difficult. In this paper, new equations are proposed for expression of transient behavior of the second order BBPLLs to phase step input. This approach gives new insights into the transient behavior of BBPLLs. Approximating transient response to reasonable specific waveform the loop transient time characteristics such as locking time, peak time, rise time and over shoot are derived with acceptable accuracy. The validity of the resulted equations is verified through simulations using MATLAB SIMULINK. Simulation results show the high accuracy of the proposed method to model BBPLLs behavior. Bang-Bang PLL,Nonlinear Operation,Transient Analysis,CDR Circuits,Alexander PD, 161 167 http://ijeee.iust.ac.ir/browse.php?a_code=A-10-348-1&slc_lang=en&sid=1 F. Mohseni-Kolagar f.mohseni@stu.nit.ac.ir 180031947532846001658 180031947532846001658 No F.Mohseni kolagar is with the Integrated Circuits Research Laboratory, Electrical and Computer Engineering Department, Babol University of Technology, Mazandaran, Babol 47148-71167. Iran H. Miar-Naimi h_miare@nit.ac.ir 180031947532846001659 180031947532846001659 Yes H. Miar-Naimi is with the Babol University of Technology, Mazandaran, Babol 47148-71167, Iran.