# Design Considerations of Multi-Phase Buck DC-DC Converter
###### Abstract
In this type of converter, the equivalent inductance reduced to each phase changes significantly within one switching cycle and thus the number of equivalent inductances increases significantly as the number of phases increases. The proposed tool not only considers the design of the coupled inductor with symmetrical inductances and coupling coefficients but also the asymmetrical design parameters. Ref. [19] proposed a new type of DC-DC converter with gallium nitride (GaN) transistors. By using additional soft switching circuits, the converter can operate with ZVS and ZCS. Thus, it allows operation at a very high frequency and has a higher efficiency compared to the classic buck-boost converter. To realize the modular design of the device, the technology of multiphase interlacing of magnetic integration is used. [PERSON]. [20] addresses the concept of multiphase hybrid buck-boost converters, showing two types (MP-HBUC and MP-HBOC) for this purpose. Due to the use of single-phase hybrid buck-boost converters (HBUC and HBOC) in their structure, the MP-HBUC and MP-HBOC topologies are characterized based on significantly reduced conduction losses compared to conventional buck-boost converters (CBUC and CBOC). In this sense, even at high load levels, MP-HBUC and MP-HBOC type converters are highly efficient. The authors of [21] present a new method for controlling multiphase step-down converters by operating with variable switching frequency. In operation, for each phase with the control frequency in the MHz range, the digital cycle-by-cycle converter control of both current and voltage results in fast transient dynamic response and correspondingly fast interference suppression. In this case, the main challenge in operating the device is adding phases or increasing the operating frequency. For this purpose, it is necessary to realize a feedback voltage measurement without the presence of disturbances from dynamic switching transients. Ref. [22] introduced a new design approach for multiphase non-isolated DC-DC topology. It is based on a new generic hybrid cell composed of a capacitor and an inductor. This approach contributed to a high degree of modularity of the obtained converters, and in this way, high conversion coefficients are achieved with higher efficiency compared to classical structures. The interaction between the capacitor and the inductor gives rise to resonant processes and leads to modes with soft commutations, which reduces losses and contributes to a higher efficiency of the converter. This method was used to construct a multiphase voltage regulator module VRM. The steady in [23], a converter designed to deliver 1 kW of power at a 42 V output voltage, is proposed to fulfill the demands of the 14/42 power system widely employed in automotive applications. The paper covers designing, analyzing, and simulating a multi-phase interleaved DC-DC boost converter tailored for 42 V power systems. This converter comprises six-phase boost converters designed to operate in the discontinuous conduction mode (DCM), effectively providing 1 kW of output power. The influence of changing the parameters on the converter's performance is also described. In [24], an enhanced fixed-frequency current-following-based digital control strategy is introduced for low-voltage, high-current multi-phase DC-DC converters that necessitate rapid transient response. The paper presents dynamic ramp compensation methods to enhance stability while maintaining high-performance levels. It has been observed recently that data center energy consumption is on the rise, primarily due to the increasing number of Internet users, the proliferation of cloud computing, and the widespread use of multi-core processors. In order to reduce the losses in the DC bus and the power distribution network, data centers follow a trend of increasing the bus voltage from 12 V to 48 V.  
In [25], a DC-DC converter is introduced to provide the interface between the 48 V bus and the existing 12 V server modules.