Power recycling using Wilkinson power combiner with pulsewidth modulation

This paper presents a method for recycling the wasted power in the isolation resistor of a Wilkinson power combiner when the input signals are not identical. An RF-dc rectifier is used to replace the isolation resistor of the Wilkinson power combiner to recycle the power that would originally be dissipated in the isolation resistor. To validate the proposed technique, a prototype modified Wilkinson power combiner is constructed using commercially available components. The power combiner is tested with a 1-MHz pulsewidth modulated (PWM) radio-frequency (RF) signal with a carrier frequency of 836.5 MHz and an input power level of 25 dBm. Measurement results show that the proposed technique achieved a maximum RF-dc conversion efficiency of 52% when the PWM duty cycle reaches 50% and retain the characteristic of a conventional Wilkinson power combiner.