Improved fast frequency response measurements of switched-mode power supplies using Dirac-ideal PRBS excitation

Frequency-domain characterization of switched-mode power supplies have become more and more popular during the last years instead of time-domain analysis. The appropriate frequency responses of power supplies have been shown to be highly effective tools in design and validation processes. This trend has yielded a number of different fast low-cost applications for obtaining the characterizing frequency responses. The unique requirements of power supplies in excitation design procedure have been understood and fast correlation-based techniques have been developed. However, the properties of the presented methods and the applied excitations have not been fully recognized and consequently, the obtained frequency responses have been often inaccurate. This paper proposes several improvements to the previously presented methods. Spectrum method, binary excitation with ideal Dirac delta function, multisampling technique and automated excitation signal design are proposed. The theory behind the proposed improvements are first reviewed and then their effect is demonstrated with practical measurements from a high-frequency switched-mode converter.