On the VLSI Implementation of Adaptive-Frequency Hopf Oscillator

In this paper, a new VLSI implementable Hopf oscillator with dynamic plasticity is proposed for next-generation portable signal processing application. A circuit-realizable piece-wise linear function has been used to govern the frequency adaptation characteristic of the proposed oscillator. Furthermore, a straightforward method is suggested to extract the frequency component of the input signal. Mathematical model of the oscillator is derived and it is shown, using VHDL-AMS model, that despite using a new nonlinear function, the oscillator exhibits the same characteristics and learning behavior as the original one with improved learning time. Subsequently, an equivalent circuit model and transistor level implementation for the oscillator is suggested and the mathematical model is confirmed with system and circuit level simulations. Capability of such oscillator to extract frequency futures without doing explicit signal processing is shown with examples of both synthetic and real-life EMG signals.