1 Control Loop Analysis

Frequency-domain analysis is important because it helps translate the time-domain switching behavior of any converter into a control-loop view that is easier to analyze, design and optimize. In the time domain, ACOT operation is understood through switching-node pulses, feedback ripple, inductor current and transient response.

However, for loop design, it is also necessary to understand how the ripple-injection network, feedback network and output LC filter shape the loop gain across frequency. S-domain analysis provides this framework by replacing resistors, inductors and capacitors with their corresponding impedances. This allows the ACOT loop to be represented using impedance ratios, making it possible to identify poles, zeros, crossover frequency and phase-margin-related behavior. In this way, S-domain analysis connects the physical ripple-injection components to the frequency-domain loop response and provides useful insight for stable and optimized ACOT design.