Chung Shan Institute of Science and Technology

Dow-Chih Niu

Chi-Yang Chang

Chia-Yang Chen

Lih-Shiang Lin

Hong-long Wung

A single-power-supply Idss-bias RF amplifier is disclosed, which is composed by the first and second stages Amplifiers. The two stages have the same circuit topology except matching circuits. The source terminal of amplifier is grounded directly to reduce a parasitic effect from a bias circuit. It will increase the stability of the RF amplifier and avoid an oscillation. The lossy matching circuits and eliminating resonator circuit are designed to make the RF amplifier unconditional stable. A variable resister is put into to adjust a D.C. voltage on the drain terminal. The current of amplifier could be controlled in a reasonable range. High gain and quit low noise have been obtained.

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The parallel-coupled-resonator coupled line filter with open-and-short end, comprises an input port for receiving an input signal; a bent first resonator and a bent third resonator where their both ends are open circuited; a second resonator whose both ends are shorted to ground; and an output port for outputting signal. Wherein, designing cross coupling between the third resonator and the first resonator to obtain a steep frequency response and reduce the interference of the image signal.

Microstrip line parallel-coupled-resonator filter with open-and-short end

A balun-transformer, which is composed of a balun transition and an impedance matching circuit. Chemical etching is employed in the manufacturing process that is compatible with the common microwave circuit manufacturing process. Using the odd mode analysis and commercial microwave software to design the balun-transformer. It is more accurate and more efficient than the conventional method to make balun-transformer that it can only be designed by experience and experiments. These balun-transformers can be used in UHF and VHF band.

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Taipei, Taiwan

Dow-Chih Niu