Bandwidth and Dynamic Response Decoupling in a Multi-phase VRM by applying Linear-Non-Linear Control

The new generation of microprocessors has imposed more exigent requirements for the power supplies, usually known as Voltage Regulator Modules (VRM), since they have to operate at lower voltage and higher current with faster transient slew rates. At present, the solutions based on an appropriate controller design become more attractive to meet the new specifications. The linear-non-linear (LnL) control strategy allows reducing the switching frequency and the number of phases compared with using a classical linear control. In addition, a digital implementation of the control provides advantages compared to analog controllers, mainly, easy design of complex control and reconfigurability. In this paper, a digital implementation of the LnL control in a four phases VRM is developed. Due to digital implementation, a system control with a bandwidth of 20 kHz and a system control with a bandwidth of 40 Hz have been easily implemented. Experimental results show that the dynamic response of a four phases VRM with LnL control strategy and a bandwidth of 40 Hz is even faster than a four phases VRM with linear control strategy and a bandwidth of 20 kHz. That means, LnL control strategy decouples the transient response and the bandwidth of the converter.