The bifurcation and chaos phenomena appeared in power system have become a focus subject at present. It has become apparent about a decade ago that power converters exhibit various types of non-linear behaviour which includes all kinds of bifurcations and chaos. Even basic DC/DC converters exhibit bifurcation and chaos phenomena as well as parallel-connected DC/DC converters and PFC system. The main source of such non-linearity is the switching mechanism of the converters. Non-linear components of the converter circuit and control scheme such as the use of naturally-sampled, constant-frequency PWM further contribute to the non-linear behaviour of converters such as a DC-to-DC buck converter. Thus, all feedback controlled power converters exhibit certain non-linear phenomena over a specific breadth of parameter values. Despite being commonly encountered by power electronics engineers, these non-linear phenomena are by and large not thoroughly understood by engineers. This paper examines the bifurcation behaviour of the buck converter in an ideal case when the input voltage is varied. The computer simulation scheme, PSPICE is employed to model the behaviour of the ideal buck converter. For certain values of the input voltage, Vin instability occurs. The analysis and conclusion presented in this paper will provide an overview of the bifurcation behaviour of the DC-to-DC buck converter, aspiring to draw attention of the power electronics and the circuits and systems communities to a field that is not often researched and examined.