Colpitts Chaotic Oscillator Coupling with a Generalized Memristor

By introducing a generalized memristor into a fourth-order Colpitts chaotic oscillator, a new memristive Colpitts chaotic oscillator is proposed in this paper. The generalized memristor is equivalent to a diode bridge cascaded with a first-order parallel RC filter. Chaotic attractors of the oscillator are numerically revealed from the mathematical model and experimentally captured from the physical circuit. The dynamics of the memristive Colpitts chaotic oscillator is investigated both theoretically and numerically, from which it can be found that the oscillator has a unique equilibrium point and displays complex nonlinear phenomena

Equivalent realisation circuit for a class of non-ideal voltage-controlled memristors

In this study, an equivalent realisation circuit with off-the-shelf components and devices is proposed, which can be used to equivalently implement a class of non-ideal voltage-controlled memristors. The mathematical models of the equivalent realisation circuit with three function arithmetic circuits are built and their fingerprints are analysed by the pinched hysteresis loops with bipolar periodic voltage stimuli. The numerical simulations are easily verified by experimental measurements, which indicate that when three function arithmetic circuits are linked, the equivalent realisation circuit can realise three non-ideal voltage-controlled memristors with different non-linearities

A Detection Circuit for Improving the Unloading Transient Performance of the COT Controller

Fast load transient response and high light-load efficiency are two key features of the constant on-time (COT) control technique that has been widely used in numerous applications, such as for voltage regulators and point-of-load converters. However, when load step-down occurs during an on-time interval, the COT controller cannot respond until the COT interval expires. This delay causes an additional output voltage overshoot, resulting in unloading transient performance limitation. To eliminate the delay and improve the unloading transient response of the COT controller, a load step-down detection circuit is proposed based on capacitor current COT (CC-COT) control. In the detection circuit, the load step-down is monitored by comparing the measured capacitor current with the preset threshold voltage. Once the load step-down is monitored, the on-time is promptly truncated and the switch is turned off. With the proposed detection circuit, the CC-COT-controlled buck converter can monitor the load step-down without any delay and obtain less output voltage overshoot when the load step-down occurs during the on-time interval. PSIM circuit simulations are employed to demonstrate the feasibility of the detection circuit