Monolithic Microwave Integrated Circuits

For 5G/6G wireless communication, high performance circuit components are required. In this area, we have designed various circuit, such as power amplifier, phase shifter and oscillator for radio frequency (RF) systems of mobile communication. Also, we focus on monolithic microwave integrated circuits (MMIC) for the highly efficient power amplifier based on CMOS, GaAs and GaN fabrication technology.

In order to solve the problem of increasing path-loss and coverage while using frequencies above 6G and beyond 5G, it is essential to implement metamaterial-based Reconfigurable Intelligence Surface (RIS). In the course of research on improving communication performance by changing the properties of electromagnetic waves by using various reconfigurable elements, we intend to implement a reception signal amplification function pointed out as a limitation of the existing RIS by combining a high-frequency CMOS circuit with RIS.

Recently, high efficiency and high output power amplifiers have been attractive for millimeter-wave wireless power transfer systems. Here, we have designed a gain-enhanced topology with high output power and high efficiency using newly devised passive device. As a result, it is possible that the link budget for wireless power transfer (>1W) could be successfully obtained. The circuit is simulated and measured through cadence and own equipment, respectively; the link budget with antenna arrays is verified by the near-field measuring setup.

Microwave has ability to focus and deliver stimulation signal to bio-tissue, especially brain. Here, we study radio frequency integrated circuits (RFIC) for generating, modulating and amplifying stimulation signal using a voltage-controlled oscillator, modulator, and power amplifier. Semi-conductor process is used to integrate the whole system into a single chip. Also, the passive probe is developed to match the bio-tissue into 50 Ohms for delivering the signal. The total stimulation system is validated by experiments on the mouse brain.