Dynamic performance comparison of current mode control schemes for Point-of-Load Buck converter application

Different current mode controls are widely adopted in commercial PWM controllers for Point-of-Load converter application. To understand the unique properties of various current mode control schemes and study the subtle differences between them, this paper investigates and compares four current mode control schemes (peak-current control, valley-current control, constant on-time control and constant off-time control) for Point-of-Load power converter and Voltage Regulator applications. Performance attributes under investigation include high bandwidth voltage loop design, adaptability to wide input voltage range, adaptive voltage positioning design and audio susceptibility. The pros and cons of these schemes are identified and explained by the unified small signal equivalent circuit model. From dynamic performance point of view, this work provides a current mode control scheme selection criteria and feedback design guideline. The theoretical analyses are verified by both simulation and experimental results.