Effects of nonlinear capacitance in feedback LC-tank on chaotic Colpitts oscillator

This manuscript presents modifications of the standard Colpitts circuit by replacing one of the capacitors in C ₁ − C ₂ potential divider by a pair of back-to-back connected diode varactor. This introduces a nonlinearity of diode varactor type in the feedback signal generation itself. The dynamic capacitance of the varactor pair varies nonlinearly with the output voltage. The proposed modification facilitates generation of enriched frequency components with enhanced power. Both C ₁ and C ₂ were alternately replaced by the diode varactor and results were compared with the standard oscillator with fixed-value capacitors. The analysis is based on basic numerical tools such as Lyapunov exponents, bifurcation diagram, phase trajectories and power spectra. (paper)