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Expert has worked for microwave/millimeter-wave systems and design active/passive circuits using MMICs for applications to satellite communications, Point-to-Point Radio, Local Multi-point Distributed Systems (LMDS), transceiver systems for space applications, and wireless communication systems for commercial applications.
The active devices that he designed include buffer amplifiers, power amplifiers, low noise amplifiers, receivers, up-converters, and mixers. The operating frequency of active device is from 17 to 43 GHz. The MMICs for these devices use 0.15 ?m GaAs pHEMT (pseudomorphic High Electron Mobility Transistor) technology to accommodate such a high frequency with high performances.

Expert also design and develop transitions for microwave/millimeter wave circuits. At microwave/millimeter-wave range, the power loss is significant when transmitting the microwave power through the transmission lines. Most of the microwave or millimeter-wave systems are composed of various kinds of transmission lines such as coax, waveguide, microstrip, coplanar waveguide (CPW), coplanar stripline (CPS), slotline, and finline etc. It is because each microwave circuit or component has its own characteristic which is suitable for certain transmission line. For the low loss microwave/millimeter-wave power transmission between components and circuits with various transmission lines, transitions between dissimilar transmission lines are required. Specifically, waveguide-to-microstrip transition can be widely used in versatile applications. Expert has done a research for this transition for low transmission loss and low returned power loss. For doing this, lots of mathematical/numerical time and frequency domain analyses are performed through the computer simulation, and practical fabrication and measurement are accomplished. Several kinds of the waveguide-to-microstrip transition are currently studied, which are used for vertical and side interface between the feeding port and circuit. With the transition, circuit would be greatly simplified by reducing several steps of transitions and low loss would be achieved by the nature of waveguide.

For the interconnection between MMICs and microstrip, bonding wire is required. This boding wire produces unnecessary inductances at high frequencies, which highly degrades the microwave/millimeter-wave circuit performances. Inductance value changes significantly as frequency moves toward higher bands. To reduce the parasitic inductances, wideband impedance matching techniques need to be studied to improve the input return loss.

Another project is designing outdoor point-to-point transceiver for the frequency range of 18 to 38 GHz using surface mount MMICs. By suing surface mount devices, boding wire is not necessary at all. Surface mount technology at the frequency range from 17 to 40 GHz is a great challenge. Undesired parasitics should be minimized for packaged surface mount MMICs. Numerical analysis using computer simulation is required and realistic implementation techniques need to be investigated.

He designed Microwave/millimeter-wave antennas for communication systems from 2 to 30 GHz.

He has consulted investors by showing certain company's prospective product lines and their positions in the industry and future. That company also does GaAs RF IC industry.
He explained from short term to long term prospect of that company purely based on technology and product line. GaAs, GaN amplifiers, BAW, SAW filters, Wi-Fi products.