Analysis of Series and Shunt DC Combination under Nonuniform RF Inputs Using an Equivalent Resistance Method

Multiple rectifiers (rectennas or arrays) have been widely adopted in nowadays wireless power transfer (WPT) and wire-less energy harvesting (WEH) systems to receive/harvest as much power as possible from multiple power sources. However, few studies focused on the overall RF-to-dc efficiency when combining the DC outputs together under nonuniform RF power inputs. In this paper, we analyze the DC combination problem using an equivalent resistance method for both the series and the shunt combining topologies. We also compare and contrast these two topologies and give some recommendations. ADS harmonic balance solver is employed to verify the proposed analysis method and those recommendations.