Jun-Hwan Sim

Eight-beam piezoresistive accelerometer fabricated by using a selective porous-silicon etching method

This paper presents the first experimental results of a piezoresistive silicon accelerometer with eight beams fabricated by a unique silicon micromachining technique using selective porous-silicon etching. This technique is capable of precisely constructing a microstructure without any lateral etching or undercutting. By the use of this eight-beam structure, the mechanical strength of the accelerometer can be highly improved due to smaller shear stress. The lower sensitivity of the sensor can be simply solved by combining the four output signals of the half-bridge. The effectiveness of the sensor is confirmed through an experiment in which the accelerometer is characterized.

The RF Power Amplifier Using Active Biasing Circuit for Suppression Drain Current under Variation Temperature

In the paper, the power amplifier using active biasing for LDMOS MRF-21060 is designed and fabricated. Driving amplifier using AH1 and parallel power amplifier AH11 is made to drive the LDMOS MRF 21060 power amplifier. The variation of current consumption in the fabricated 5 Watt power amplifier has an excellent characteristics of less than 0.1A, whereas passive biasing circuit dissipate more than 0.5A. The implemented power amplifier has the gain over 12 dB, the gain flatness of less than 0.09dB and input and output return loss of less than -19dB over the frequency range 2.11~2.17GHz. The DC operation point of this power amplifier at temperature variation from to is fixed by active circuit

Eight-beam piezoresistive accelerometer fabricated by using a selective porous silicon etching method

This paper presents the first experimental results of a piezoresistive silicon accelerometer with eight beams fabricated by a unique silicon micromachining technique using selective porous silicon etching. This technique is capable of precisely constructing a microstructure without any lateral etching or undercutting. By the use of eight-beam structure, the mechanical strength of the accelerometer can be highly improved due to smaller shear stress. The lower sensitivity of the sensor can be simply solved by combining four output signals of half-bridge. The effectiveness of the sensor is confirmed through an experiment in which the accelerometer is characterized.