Locating current paths via time synchronized measurements in a multiphase DCDC buck converter and a high frequency analytical model for the common-mode impedance of a ferrite choke

In the first section, it introduces a novel method to localize current from multiple sources. The identification of return current paths is often a key element in understanding the root cause of a product\u27s radiated emissions. In a complex system, multiple sources can contribute to the current at the same location and frequency. The source of the current can be identified by correlating the current to different sources. However, the multiphase buck converter phases do not switch at the same time. Thus, synchronizing to a specific phase makes it possible to determine how the current from a specific phase spreads throughout the board. With the objective of localizing current, one can determine whether the capacitor placement is optimal and improve the layout and placement solutions for a multiphase buck converter. In the second section, it presents a novel analytical model to model the ferrite choke. Ferrite chokes are widely used to reduce the common mode current in power systems. For certain systems, changes in total common mode impedance due to a ferrite are important to characterize the behavior of the ferrite. However, the change in impedance due to the ferrite on the structure depends not only on the ferrite frequency response, but also on the system structure and the location of the ferrite. This paper presents a novel high-frequency analytical model for the common mode impedance of ferrite chokes. This model was developed based on transmission line theory to predict the impact of various ferrite chokes on common mode currents in wire harnesses using a closed-form equation. It more clearly explains the physical meaning of the internal mechanism of the ferrite and agrees well with experimental results on a wide bandwidth up to 1 GHz --Abstract, page iii

The equation of state for scalar-tensor gravity

We show that the field equation of Brans-Dicke gravity and scalar-tensor gravity can be derived as the equation of state of Rindler spacetime, where the local thermodynamic equilibrium is maintained. Our derivation implies that the effective energy can not feel the heat flow across the Rindler horizon.Comment: 6 pages, to be published in Prog. Theor. Phy