榎原 晃

In this paper we have proposed a five-way power divider using unequal LC-ladder dividers. The LC-ladder divider is a compact power divider based on the Wilkinson power divider to solve size problem at a low frequency band (UHF) used by IoT devices. According to the circuit analysis, the proposed circuit can realize 67.5% bandwidth and flat transmission characteristics. In order to confirm actual operation of the divider, we have carried out electromagnetic analysis and measurement.

This paper deals with an unequal power divider with two matching frequencies by using LC-ladder circuits. This circuit that is constructed based on the Wilkinson power divider, consists of 9 elements. This circuit can achieve the same or wider bandwidth as the original one by holding the two matching frequencies close together. In order to confirm the practicality in IoT, the design center frequency is set to 920 MHz, and its actual measurement is carried out after circuit pattern design and analysis.

We designed and evaluated 1×2 and 2×2 optical couplers using multimode interference (MMI) optical waveguides of Ti-diffused LiNbO3. A Mach-Zehnder electrooptic modulator (MZM) designed using those two MMI couplers as an optical power splitter and combiner was fabricated. Optical intensity modulation was achieved with a 50 dB extinction ratio. And the experimental results showed that the 2 ×2 MMI optical coupler could provide nearly equal power division with a 90° phase difference as a 90° hybrid. Next, we applied the MZM structure to the single sideband (SSB) modulation. 10 GHz microwave signals of 90° phase difference were fed to the modulation electrodes on the two arms of the MZM. The SSB modulation operation was confirmed from output light spectra, and the sideband suppression ratio of 39 dB was observed by miner adjustment of the optical phase bias.