Novel Equivalent Current Model for GaN-Based High-Efficiency Microwave Rectification

In this article, a novel equivalent current model of Schottky diode loss is proposed to guide the design of microwave rectifiers and semiconductor devices. The model employs an equivalent forward current equation based on charge conservation and Kirchhoff's voltage law to achieve an accurate calculation of the diode's turn-on period and losses under the influence of current harmonics. The estimation from the proposed model is compared with the results from harmonic balance simulation and the resultant error is within 1%. Once the diode's SPICE parameters, working frequency, load resistance, and input power are given, the maximum efficiency of the rectifier circuit can be accurately predicted. Guided by the proposed model, a GaN diode and a rectifier were designed and fabricated to operate at 915 MHz. The measured maximum conversion efficiency reaches 92.3% when the input power is 23 dBm. The high-efficiency power range (efficiency \ge80 %) and the load bandwidth (efficiency \ge50 %) are extended from 16.5 to 25 dBm and from 700 to 7400~\Omega , respectively. The consistency between the test and the calculated results validates the effectiveness of the proposed model.