Satoshi Yoshida

C band GaN diode rectifier with 3W DC output for high power microwave power transmission applications

This research reports a 5.8-GHz band GaN (Gallium Nitride) diode rectifier for high power microwave power transmission (MPT) systems. Designed rectifier is fabricated and measured. The fabricated rectifier has Cu heat sink because of the high power operation. The GaN diode is directly mounted on the heat sink. Also, fabricated substrate is screwed to the heat sink. Measured RF-DC conversion efficiency and output DC power at 5.9GHz are 32.6% and 3042mW, respectively. This report makes a first step for future miniaturization by the hybrid semiconductor integrated circuit (HySIC) technology which utilizes different type semiconductor devices.

Design of dual-band rectifier using microstrip spurline notch filter

This paper proposes and demonstrates a novel dualband rectifier at 2.45 GHz and 5.8 GHz. The proposed rectifier employs a microstrip spurline notch filter to realize dual-band high RF-DC conversion efficiency. The control of reflected signals from the output filter to maximize the voltage swing at the diode, and use of the spurline notch filter provide high-level conversion efficiencies at both operating frequency bands. The fabricated proposed dual-band rectifier achieves the RF-DC conversion efficiencies of 55.9 % and 55.4 % at 2.15 GHz and 5.84 GHz, respectively. These results are top-level performances of the dualband rectifiers.

Short-range 4×4 MIMO Wireless Communication and Power Transfer system

This paper investigated coexistence possibility of high efficiency Wireless Power Transfer (WPT) system and high-speed communication system in Short-range Wireless Communication and Power Transfer (WiCoPT) system. To realize both high power transfer efficiency and high data rate, this paper proposes the WiCoPT system, which is supported by the Short-Range Multiple Input and Multiple Output (SR-MIMO) transfer technique. Relationship between the antenna element spacing and the transmission performance was analyzed to clarify the maximum performances of the power transfer efficiency and the data rate. The paper analyzed and demonstrated a 4×4 MIMO WiCoPT system. The numerical analysis indicates that the antenna element spacing to maximize the power transfer efficiency is different from that to realize the highest channel capacity. In addition, the analysis clarifies there are two suitable antenna element spacing for high power transfer operation. Therefore, our proposing system chose the antenna element spacing to realize the second peak for the high-level power transfer efficiency simultaneously. The 4×4 MIMO WiCoPT system achieved a channel capacity of 45 bit/s/Hz and a power transfer efficiency of 64.8 %.

C-band energy harvester by Si RFICs with GaN diodes for microwave power transfer

A compact C-band energy harvester is designed, test fabricated, and measured. An RF hybrid semiconductor integrated circuit (RF-HySIC) rectifier was fabricated by comprising a Si RFIC matching circuit and a GaN diode. The energy harvester at 5.8-GHz was made in a multi-circuit fashion under a wide input power range and input power control by field-effect transistor switch. The maximum RF-DC conversion efficiencies from a proto type of RF-HySIC rectifier with 50% and 13% were achieved at 5.1 and 5.8 GHz, respectively.

Design of concurrent dual-band rectifier with harmonic signal control

This paper proposes and demonstrates a concurrent 2.45GHz/5.8GHz rectifier. The proposed concurrent dual-band rectifier drastically improves its RF-DC conversion efficiency with a harmonic signal control technique. The proposed rectifier employs two key designs. A microstrip spurline notch filter in the output section realizes high RF-DC conversion efficiencies at the dual bands. The quarter-wave length open stub of the 8.25 GHz connected at diode cathode effectively terminates the harmonic signal generated by mixing the input signals. The proposed configuration provides the high RF-DC conversion efficiency even when two-tone signals input the rectifier. The fabricated the dual-band rectifier achieves the RF-DC conversion efficiencies of 64.8 %, 62.2 %, and 67.9 % at 2.45 GHz, 5.8 GHz, and their two-tone input signals, respectively.

Hybrid semiconductor integrated recitifer for wireless power transmission into spacecraft

This paper reports on a rectifier with 100 mW class dc output at 5.8 GHz using a gallium nitride (GaN) shottly barrier diode and silicon (Si) matching circuit. The originality of the study lies in its adaptation of the hybrid semiconductor integrated circuit (HySIC) technology that utilizes different types of semiconductors. We have completed the basic steps for developing a rectifier based on the HySIC technology. A nonlinear measurement system of GaN diodes with a jig was constructed and an equivalent circuit model of the diode was established. Based on the diode model, a Si matching circuit was designed. The size of the HySIC rectifier was 3.9 mm×9.5 mm. The RF-dc conversion efficiency of the HySIC rectifier was 10.3% at 5.8 GHz.

Evaluation of a C-band rectifier using Si substrate for HySIC application

This paper demonstrates fundamental evaluation results of a C-band rectifier using Si substrate for HySIC application. Usage of the Si substrate is attractive for future integration with other mixed signal circuit. Because of large loss tangent of the Si substrate, applicability as a circuit substrate to the C-band rectifier is discussed. Two types of the rectifier, conventional printed circuit board and the Si substrate, are designed and fabricated. Maximum rectification efficiency of 10.4 % at 5.39 GHz while the load resistance is 20 Ω is obtained from the measurement.