Forced chaos generator with CMOS variable active inductor circuit

We propose a forced chaos generator with a CMOS variable active inductor circuit. The equivalent inductance of the variable active inductor in the proposed circuit can be controlled by an external voltage. Therefore, the oscillation frequencies of the circuit can be altered by applying an external periodic square waveform. As a result, we can generate chaos from the circuit. We then confirm the folding-and-stretching mechanism of the chaotic motion in the circuit. Complex phenomena, observed in the proposed circuit, are analyzed through the Poincaré sections from the SPICE simulations with TSMC 0.35μm CMOS semiconductor process parameters. In addition, we define a return map on the Poincaré section to examine the properties of the observed attractors. Moreover, we investigate the bifurcation phenomena when the amplitude and period of the external signal are changed as bifurcation parameters.