Inducing chaos in MOSFET-based electronic circuits

We construct a nonlinear, MOSFET-based electronic circuit and address the question of inducing chaos. A recently proposed method makes use of resonant perturbations, which is applicable to situations where chaos is desired, under the following three constraints: (1) the circuit operates in a stable periodic regime, (2) no parameters or state variables of the circuit are directly accessible to adjustment, and (3) the circuit equations are not available. We argue that phase-locked loops can be utilized to realize resonant perturbations in terms of frequency and phase match, and demonstrate experimentally that chaos can be induced in the MOSFET circuit.