Abstract: Disclosed is a dual-band voltage-controlled oscillator using bias switching and output-buffer multiplexing. The dual-band voltage-controlled oscillator includes a power supply unit for supplying a source voltage; plural voltage-controlled oscillation units for outputting different oscillation frequencies according to controls of a certain tuning voltage; plural bias units for generating driving voltages for driving the voltage-controlled oscillation units and supplying the driving voltages to the voltage-controlled oscillation units; and plural buffers for selectively outputting oscillation frequencies of the plural voltage-controlled oscillation units. The present invention implements the dual-band voltage-controlled oscillator through bias switching and output-buffer multiplexing, which brings an advantage of elimination of interference between output frequencies to enhance phase noise characteristics.

Abstract: A method of manufacturing a semiconductor device including a contact plug includes forming an insulation interlayer pattern and a protection pattern for protecting the insulation interlayer pattern using a mask pattern. The insulation interlayer includes a contact hole through which a surface of the substrate is partially exposed. A spacer is formed on a sidewall of the contact hole, and a first conductive layer is formed to a sufficient thickness to fill up the contact hole. The first conductive layer makes contact with the substrate at the exposed surface thereof. A contact plug is formed in the contact hole by removing the first conductive layer until a top surface of the insulation interlayer pattern is exposed. Accordingly, a contact failure between the contact plug and a conductive pattern adjacent to the contact plug is prevented.

Abstract: A Ultra WideBand (UWB) substrate type dipole antenna is provided which has a stable radiation pattern. The UWB substrate type dipole antenna includes a dielectric substrate, a first radiator formed on a side of the dielectric substrate, a signal line transmitting an energy from a coaxial cable to the first radiator, and a plurality of second radiators formed at a predetermined distance from the first radiator and the signal line, and respectively having therein a plurality of slits of a predetermined configuration. Because there is no leakage of electric current to an outer part of an external conductor of the coaxial cable, even when the connection of the connector and the coaxial cable to the antenna, distortion of the radiation pattern of the antenna is prevented. As a result, the same radiation pattern and the direction of maximum radiation may be obtained before and after connection with the connector and the coaxial cable.

Abstract: A planar antenna manufactured by patterning a substrate consisting of a dielectric layer, and first and second conductive layers applied, respectively, to both opposite surfaces of the dielectric layer. A first slot is formed in the first conductive layer for radiating electric waves. A second slot is formed in the first conductive layer for intercepting a particular frequency of the electric waves radiated by the first slot. A power supply portion is formed with the first conductive layer for supplying electric current to the first slot. A radiating element formed with the second conductive layer, which is excited by the electric waves radiated by the first slot, and radiates the electric waves.

Abstract: A planar antenna manufactured by patterning a substrate consisting of a dielectric layer, and first and second conductive layers applied, respectively, to both opposite surfaces of the dielectric layer. A first slot is formed in the first conductive layer for radiating electric waves. A second slot is formed in the first conductive layer for intercepting a particular frequency of the electric waves radiated by the first slot. A power supply portion is formed with the first conductive layer for supplying electric current to the first slot. A radiating element formed with the second conductive layer, which is excited by the electric waves radiated by the first slot, and radiates the electric waves.

Abstract: A multi-band radio frequency (RF) receiving method in a mobile communication system having a reduced size and cost includes receiving RF wave signals for four or more non-overlapping bands, primarily filtering a first wide band including adjacent first and second bands and a second wide band including adjacent third and fourth bands from the received RF wave signals, low-noise amplifying the RF wave signals of the first and second wide bands, respectively, secondarily filtering a third wide band including adjacent second and third bands and a fourth wide band including first and fourth bands from the low-noise amplified RF wave signals of the first and second wide bands, generating two band RF wave signals to be simultaneously received, and frequency-down converting the two band RF wave signals generated in the secondary filtering step into two band intermediate frequency wave signals by means of first and second oscillation frequencies.

Abstract: After an insulation layer is formed on a substrate, a contact hole is formed through the insulation layer. A recessed plug is formed to partially fill up the contact hole. The recessed plug has a height substantially smaller than a depth of the contact hole. A metal wiring structure is formed on the recessed plug and on the insulation layer. A lower portion of the metal wiring structure, formed within the contact hole, prevents damage to the recessed plug during an etching process for forming the metal wiring structure. Therefore, the recessed plug may be formed without damage thereof even if an alignment error occurs between an etching mask and the recessed plug during metal wiring structure formation.

Abstract: A linear mixer circuit with a current amplifier has an excellent linearity by using RF open-load and an improved current amplifier. Therefore, a voltage-current converting stage and a current-voltage converting stage in a conventional mixer circuit can be omitted. Further, by using the RF open-load and the current amplifier together, a current type input signal can be transmitted as it is, and non-linearity due to the voltage-current converting stage and the current-voltage converting stage can be prevented. Furthermore, bias current of the amplifying stage and the switching stage can be separated by using the RF open-load, so that an image frequency can be filtered by the RF open-load.

Abstract: An apparatus for generating an in-phase/quadrature-phase (I/Q) signal in a wireless transceiver is disclosed, including a local oscillator for generating a local oscillation signal, and first and second mixers for mixing the oscillation signal with a transmission/reception signal to convert the transmission/reception signal into a baseband or high-frequency signal. The apparatus includes a phase locked circuit for controlling the local oscillator, and a polyphase filter installed between the local oscillator and the mixers, for separating the oscillation signal from the local oscillator into an I signal and a Q signal depending on a control signal from the phase locked circuit, and outputting the separated I and Q signals to the first and second mixers, respectively.

Abstract: Provided is a multiband low noise amplifier including a first transistor, an input matching circuit, and a first capacitor. The first transistor includes a collector electrically connected to a first power supply, a grounded emitter, and a base connected to the other end of a first inductor having one end as an input end of the low noise amplifier. The input matching circuit is connected between the collector and the base of the first transistor. The first capacitor connected to the collector of the first transistior. The input matching circuit includes a varactor. The input matching circuit includes a second capacitor connected to the varactor. The input matching circuit includes a first resistor connected to the varactor. In the multiband low noise amplifier, a varactor having a variable capacitance is installed at an input end, thereby easily performing band switching through bias voltage control by a small amount and minimizing noises that may be caused by a control signal.

Abstract: An impulse generation circuit is provided for generating an impulse using a transmission line. Impulse characteristics of the impulse generation circuit are varied with the length of a transmission line rather than the characteristic variation of various devices used therein. The length of the transmission line is adjusted, such that a width of a generated pulse is adjusted. Because an end of the transmission line is short-circuited, the transmission line length can be easily adjusted on a substrate, and a ringing phenomenon due to re-reflection can be removed using termination impedance.

Abstract: A compact multilayer band-pass filter using an interdigital capacitor which can be integrated into a compact form in a relatively low frequency band. The band-pass filter filters only a signal of a predetermined frequency band from a signal applied through an input terminal, and outputs a filtered signal to an output terminal. The band-pass filter includes at least one pair of transmission lines, respectively formed between the input terminal and the output terminal provided on an uppermost layer, for generating an inductor component, a capacitance compensation unit, with the interdigital capacitor having a plurality of layers, for loading a specified capacitance to one end of the transmission line, and a ground layer coupled to a specified layer of the capacitance compensation unit and the other end of the transmission line and formed on a lowermost layer.

Abstract: A tunable wideband bandpass filter that can digitally vary the center frequency and bandwidth of a signal to be filtered, and includes a plurality of switched-capacitor banks for varying capacitance and converting the center frequency and bandwidth into a digital signal, and a plurality of inductors provided for inductance to generate the center frequency, the plurality of switched-capacitor banks that may be integrated into a signal chip.

Abstract: A miniaturized ultra-wideband microstrip antenna, includes: a dielectric substrate; a feed line disposed on the dielectric substrate, and supplying an electromagnetic energy supplied from an external power source; a main radiating element radiating the electromagnetic energy inputted by the feed line; and at least one sub-radiating element disposed in proximity to the main radiating element for multi-radiation. Also, the antenna further includes at least one connection plate electrically connecting the main radiating element to at least one of the sub-radiating elements. The miniaturized ultra-wideband microstrip antenna can also be made ultralight, and include additional sub-radiating elements besides the main radiating element, whereby multi-radiation in UWB's range can be attained.

Abstract: An ultra-wideband antenna having an isotropic radiation pattern includes a support plate, a feed line on the support plate, a radiating element connected to the feed line to transmit and receive signals, and a ground plate spaced apart from the feed line and attached to the support plate. The radiating element has at least two intersecting conductive plates.

Abstract: A field of the spread spectrum transmission of information is performed by chaotic signals.

Abstract: A small broadband monopole antenna including a shorted patch and a probe with a strip line that are electromagnetically coupled with each other. The probe with a strip line has a length of about ?/4, where ? is a wavelength. The strip line may be one of a spiral type, a folded type and a helix type. A resonance frequency of the antenna can be adjusted by varying the inductance and the capacitance of the resonance circuits. In addition, a double-band antenna or a single-band antenna having a broad bandwidth can be designed in accordance with application purpose of the antenna.

Abstract: An isotropic antenna system includes a first antenna for transmitting/receiving electric waves when a cover member installed to be capable of being open or closed with respect to a main body is open, a second antenna for transmitting/receiving electric waves when the cover member is closed, and a switching portion for selectively switching at least one of the first and second antennas to a predetermined RF circuit module according to the opening or closing of the cover member.

Abstract: An apparatus and method for self-calibrating mismatching orthogonal signals and non-linearity of a circuit occurring in a mobile transceiver. For this, in a mobile terminal, a transmitter is used as a signal generator and a receiver is used as a response characteristic measurer. A base band processor calibrates mismatching signals and non-linearity in a reception side and a transmission side, based on a test signal received via the transmitter and a test signal received via the receiver.

Abstract: An apparatus and method for compensating for the frequency offset of a received signal in a receiving apparatus of a mobile communication system. In the present invention, a sine component is calculated by adding I and Q channel signals resulting from downconverting a training sequence inserted between data symbols, and a cosine component is calculated by subtracting the Q channel signal from the I channel signal. Using the cosine and sine components at two time points, tangent components for the two time points are computed and thus first and second phase values are obtained. The frequency offset is estimated by determining the slope of a second-order line derived from the first and second phase values. The frequency offset of the received signal is compensated for based on the estimated frequency offset.