Abstract: A protective structure having a plurality of protection regions extending along closed lines arranged inside each other. Each intermediate protective region is tangent to two different adjacent protective regions, at different areas, so as to form a connection in series with the adjacent protective regions. The protective structure can be of resistive material, such as to form a series of resistors, or it can include doped portions alternately of P- and N-type, such as to form a plurality of anti-series arranged diodes. The structure can be made of polycrystalline silicon extending on the substrate surface, or can be integrated (implanted or diffused) inside the substrate.

Abstract: A control system provides an improvement in the stability and immunity to noise characteristics without degrading performance of the circuit by including a multiplier circuit that is purposely made nonlinear. A parameter K of the multiplier circuit is not a fixed value, but varies as a function of the error signal amplitude that is applied to one of the two inputs of the multiplier circuit. Advantageously, the parameter K of the multiplier circuit decreases when the amplitude of the error signal input thereto decreases.