Nonlinear digital control breaks bandwidth limitations

Abstract

The bandwidth achievable by using linear control in SMPS is limited either by the switching frequency or by the robustness of the system. Fast transient response requires high switching frequency. However, lower switching frequencies could be more suitable to maximize efficiency. On the other hand, if high switching frequency is not a problem, high bandwidth is difficult to obtain because of noise, plant variation and non-idealities of the error amplifier. This paper proposes two different approaches based on the combination of nonlinear control with linear control to break these limitations. These strategies are applied for dynamic voltage scaling and two prototypes are built to validate the concepts.