On the dynamics of a periodic Colpitts oscillator forced by periodic and chaotic signals

• Dynamics of a forced periodic Colpitts oscillator (CO) is studied.
• Forcing signal (periodic or chaotic) is generated in CO by tuning dc bias current.
• CO forced by periodic signal becomes chaotic through period doubling route.
• Conditionally phase synchronized chaos is generated for chaotic forcing.
• Experimental results corroborate findings of numerical simulation.

In this paper, we have examined effects of forcing a periodic Colpitts oscillator with periodic and chaotic signals for different values of coupling factors. The forcing signal is generated in a master bias-tuned Colpitts oscillator having identical structure as that of the slave periodic oscillator. Numerically solving the system equations, it is observed that the slave oscillator goes to chaotic state through a period-doubling route for increasing strengths of the forcing periodic signal. For forcing with chaotic signal, the transition to chaos is observed but the route to chaos is not clearly detectable due to random variations of the forcing signal strength. The chaos produced in the slave Colpitts oscillator for a chaotic forcing is found to be in a phase-synchronized state with the forced chaos for some values of the coupling factor. We also perform a hardware experiment in the radio frequency range with prototype Colpitts oscillator circuits and the experimental observations are in agreement with the numerical simulation results.