Abstract: Provided are a hetero-junction bipolar transistor (HBT) that can increase data processing speed and a method of manufacturing the hetero-junction bipolar transistor.

Abstract: Provided is a dielectric waveguide filter. The filter includes: a multi-layered structure of dielectric substrates having first and second ground planes at its top and bottom; first, second, and third waveguide resonators disposed at multiple layers within the multi-layered structure; converters for signal transition between input/output ports and the first and third waveguide resonators; first vias for forming the first, second, and third waveguide resonators; and second vias disposed at a boundary surface of the first waveguide resonator and the third waveguide resonator.

Abstract: Provided is an optical module used in a communication system employing a radio over fiber (ROF) technology delivering a radio frequency (RF) signal through an optical fiber. The optical module includes: an optical device; a signal line for transporting a radio frequency (RF) signal input from an external circuit to the optical device; and a resistor separately disposed from the signal line and having one end connected with the optical device, wherein the input impedance seen from the signal line is matched by the resistor. A bias voltage supplied to operate the optical device is applied through an inductor connected to the signal line between the optical device and a filter. Here, the filter formed by a pattern of the signal line prevents the bias voltage from being supplied to the external circuit. In order to amplify the RF signal input from the external circuit, an amplifier may be connected between the external circuit and the filter.

Abstract: Provided is an air cavity module for a planar type filter operating in millimeter-wave frequency bands. The air cavity module includes: the planar type filter operating in the millimeter frequency bands; an air cavity having open side and top surfaces to mount the planar type filter therein; and an air cavity cover closing up the open top surface of the air cavity to allow the transmission of signals from and into the planar type filter. The air cavity module can lessen both transmission loss and radiation loss to improve the characteristics of the filter that operates in the millimeter-wave frequency bands.

Abstract: Provided is a narrowband microstrip type bandpass filter adapted- to a home network, telematics, an intelligent traffic system, and a satellite Internet, the microstrip type bandpass filter comprising: an input terminal for receiving a predetermined signal; an output terminal for outputting a selection signal in a characteristic band; a first resonator electrically coupled with at least a portion of the input terminal; a second resonator electrically coupled with at least a portion of the first resonator; and a third resonator electrically coupled with at least a portion of the output terminal and the second resonator, and a magnetic coupling is provided using a cross coupling gap or a cross coupling line between non-adjacent resonators, so that a pattern can be simplified by optimizing the design and the manufacturing process to provide low-cost millimeter-wave parts, the manufacturing cost can be reduced by miniaturizing the parts, and the mass production can be readily realized.

Abstract: The present invention relates to a microstrip band pass filter and, more specifically, to a microstrip band pass filter using end-coupled stepped impedance resonators that can be used in a millimeter wave band, wherein the microstrip band pass filter comprises: a dielectric substrate; a conductor plate located on a lower surface of the dielectric substrate; and an input terminal, a plurality of SIRs and an output terminal located on an upper surface of the dielectric substrate in series, wherein the input terminal, the plurality of SIRs and the outputs terminal are conductors and end-coupled through gaps, whereby the microstrip band pass filter has a good attenuation characteristic and a narrowband characteristic, and is insensitive to the manufacturing error, and a fine frequency transition can be made without distortion just with width adjustment of the low impedance transmission line of the SIR.