Abstract: A frequency synthesizer in an ultra wide band (UWB) wireless communication system which transmits and receives data through multiband includes a frequency generation means which generates a plurality of frequency signals; and a frequency adjustment means which receives the plurality of frequency signals from the frequency generation means and generates center frequencies of all or part of sub-bands within the UWB through the frequency adjustment. Since all of the center frequencies of the sub-bands are generated, the utilization of the sub-bands can be enhanced for the wideband wireless communication. Furthermore, it is possible to enable the stable UWB communications by flexibly utilizing all of fourteen sub-bands since the sub-bands suffer less from the frequency interference in a complicated and variable wireless frequency environment.

Abstract: A source coupled differential complementary Colpitts oscillator is described, which enables a differential oscillation and also can improve phase noise performance by source-coupling a complementary Colpitts oscillator using an inductor. A differential complementary Colpitts oscillator includes: a plurality of complementary Colpitts oscillators and a source coupler which couples a source node of the plurality of complementary Colpitts oscillators, enables the Colpitts oscillators to differentially oscillate.

Abstract: A system and a method for self calibrating a voltage-controlled oscillator (VCO). In the system, a mode controller generates a control signal for each of an automatic band selection mode, an automatic gain tuning mode, and a phase-locking mode, from a frequency comparison result between a reference clock signal and a divided clock signal which is generated by dividing a frequency of an oscillation signal, and thereby controls the VCO, so that the VCO may generate the oscillation signal which is automatically phase-locked in a target frequency with an optimal state.

Abstract: A CMOS amplifier of a filter for an ultra wideband application and a method of the same are provided. In the CMOS amplifier, an active load circuit adds a Zero location and increases a gain by MOSFETs, feeding back operation, and has a property of a high gain and a wide bandwidth. When the CMOS amplifier is applied to a biquad LPF, a high voltage linearity over about 200 mV peak-to-peak and an suitable ultra wideband property over about 320 MHz of an cutoff frequency may be achieved.

Abstract: A frequency synthesizing apparatus and method having an injection-locked quadrature VCO in an RF transceiver is provided. In the frequency synthesizer, an I signal following a frequency of a high frequency signal that is input using the injection-locked quadrature VCO and a Q signal thereof are simultaneously generated to have an appropriate driving power. Accordingly, the I signal and the Q signal thereof that are generated in the injection-locked quadrature VCO may be utilized as a local signal for frequency up/down-conversion, without being buffered. An output of an SSB mixer may be directly input into the injection-locked quadrature VCO. Also, high frequency signals that are generated in another circuit such as the SSB mixer, a PLL, or a VCO may be selected to be input into the injection-locked quadrature VCO by a selector.

Abstract: An inductor used in a radio frequency integrated circuit is disclosed. The inductor includes a plurality of unit inductors each having a vertical spiral structure, wherein a vertical cross-section of at least one unit inductor selected from the plurality of unit inductors is an inverted trapezoid.

Abstract: A dual gate cascade amplifier includes a first transistor and a second transistor electrically connected in series, the second transistor including a first parallel transistor and a second parallel transistor, the first parallel transistor and the second parallel transistor being electrically connected in parallel, a first channel electrically connecting a first end channel region of the first transistor and a second end channel region, wherein one of the first or second end channel regions is a source and the other of the first or second end channel regions is a drain, the second end channel region being a common end channel region shared by the first and second parallel transistors, and a second channel electrically connected to the second end channel region and extending away from the first transistor.

Abstract: A frequency synthesizer in an ultra wide band (UWB) wireless communication system which transmits and receives data through multiband includes a frequency generation means which generates a plurality of frequency signals; and a frequency adjustment means which receives the plurality of frequency signals from the frequency generation means and generates center frequencies of all or part of sub-bands within the UWB through the frequency adjustment. Since all of the center frequencies of the sub-bands are generated, the utilization of the sub-bands can be enhanced for the wideband wireless communication. Furthermore, it is possible to enable the stable UWB communications by flexibly utilizing all of fourteen sub-bands since the sub-bands suffer less from the frequency interference in a complicated and variable wireless frequency environment.

Abstract: Disclosed are a variable gain differential amplifier, and variable degeneration impedance control device and method for use in the variable gain differential amplifier, which can adjust an amplification gain and ensure linearity. A DC level of a differential signal to be amplified by the amplifier is adjusted according to a control signal to adjust a gain of the amplifier, and the impedance of a variable degeneration impedance part is adjusted according to the differential signal of which the DC level is adjusted. That is, the gain of the differential amplifier is adjusted and the linearity is ensured by varying the impedance of the variable degeneration impedance part using the differential input signal of which the DC level is adjusted.

Abstract: A frequency synthesizer for mixing reference frequencies using at least one control signal has a local oscillator, frequency dividers for dividing a frequency generated from the local oscillator and generating at least one control signal, and a single side band (SSB) mixer for mixing the reference frequencies, using the frequency generated from the local oscillator and the control signal. The frequency synthesizer has a simplified structure, and can easily mix reference frequency signals without a need for additional power.

Abstract: Provided is a complementary metal oxide semiconductor variable gain amplifier controlling a dB linear gain and a method of controlling the dB linear gain. The complimentary metal oxide semiconductor variable gain amplifier includes: first through fourth transistors differentially receiving first and second input voltages and amplifying the first and second input voltage using a predetermined gain; fifth and sixth transistors controlling a transconductance according to a control voltage to control the predetermined gain; and first and second resistors generating an output voltage having the predetermined gain according to an output current generated by the fifth and sixth transistors.

Abstract: A ring oscillator and a phase error calibration method are provided. The ring oscillator may include a first voltage-current converter for controlling and outputting an amount of tail current Itail according to a magnitude of a first control voltage applied in feedback in a PLL circuit; a second voltage-current converter for controlling and outputting an amount of shift current according to a magnitude of a second control voltage applied from a system phase error detector; and differential amplifiers for controlling, for output signals, a delay time of signals based on the applied tail current amount and a shift time of the signals based on the shift current amount. Thus, a phase relation between in-phase and quadrature-phase signals outputted from the ring oscillator may be controlled.

Abstract: A digital-to-analog converter converts a digital input signal into an analog signal. The digital-to-analog converter includes: a power-supply unit for outputting voltages of different magnitudes through plural output terminals thereof; plural switches connected to the plural output terminals, which are controlled on and off, and are for applying the output voltages of the power-supply unit or a ground voltage to a next stage; and plural source transistors connected to the plural switches for outputting currents of magnitudes corresponding to the voltages applied from the respective connected switches of the plural switches. The plural source transistors are designed to have the same operating characteristics, thereby improving glitch characteristics.

Abstract: A receiver includes first switches for applying either differential signals of an oscillator or a data signal of a transmitter to down-converting mixers; a frequency conversion unit for mixing and applying to the down-converting mixers quadrature signals generated from an arbitrary clock signal generator and the oscillator, and having a PPF for changing a phase difference of I/Q signals according to a control voltage externally applied; a phase difference detection part for checking a phase difference between the I/Q signals and generating the control voltage to be applied to the PPF according to the phase difference so as to correct the phase difference; third switches for applying the data signal processed through the down-converting mixers, filters, and amplifiers to A/D converters and applying the I/Q signals having a predetermined frequency to the phase difference detection part; and a control unit for switching the first and third switches.

Abstract: A low noise amplifier (LNA) for ultra wide band recives and amplifies identical RF signals in different frequency bands, and includes more than one pair of narrow band LNAs coupled in parallel, and a load circuit which increases load impedance of the entire circuit of the narrow band LNAs. The LNA can not only amplify the RF signal in the UWB but also obtain the low noise and the high gain that are features of the conventional narrow band LNA.

Abstract: A high-capacitance capacitor having a multi-layered vertical structure for use in an RF circuit is disclosed. The capacitor includes an upper electrode, a lower electrode, and a dielectric layer interposed between the two electrodes. A plurality of electrodes is formed in parallel in the dielectric layer in a diagonal direction. First electrodes, which are half of the plurality of electrodes, are coupled to only the upper electrode, while second electrodes, which are the other half of the plurality of electrodes, are coupled to only the lower electrode. The first electrodes and the second electrodes are alternately positioned in rows and columns. The capacitor does not require additional processes, thereby reducing complexity and cost of fabrication thereof.

Abstract: A dual gate cascade amplifier includes a first transistor and a second transistor electrically connected in series, the second transistor including a first parallel transistor and a second parallel transistor, the first parallel transistor and the second parallel transistor being electrically connected in parallel, a first channel electrically connecting a first end channel region of the first transistor and a second end channel region, wherein one of the first or second end channel regions is a source and the other of the first or second end channel regions is a drain, the second end channel region being a common end channel region shared by the first and second parallel transistors, and a second channel electrically connected to the second end channel region and extending away from the first transistor.

Abstract: An inductor used in a radio frequency integrated circuit is disclosed. The inductor includes a plurality of unit inductors each having a vertical spiral structure, wherein a vertical cross-section of at least one unit inductor selected from the plurality of unit inductors is an inverted trapezoid.

Abstract: A multiband RF transmitting and receiving apparatus and a method therefore is capable of using a control voltage from a phase locked loop (PLL) to control other components, as well as a voltage controlled oscillator (VCO), of a multiband RF transceiver. The multiband transmitting and receiving apparatus adjusts a capacitance value of a varactor in a power amplifier (PA) and a low noise amplifier (LNA) including an LC parallel resonance circuit, respectively, using the control voltage from the PLL and controls a current flowing to a mixer. Accordingly, the components in the multiband RF transceiver are able to operate a greater number of frequency bands than a single frequency band, thereby reducing the number of components required to design the multiband RF transceiver.

Abstract: A high-capacitance capacitor having a multi-layered vertical structure for use in an RF circuit is disclosed. The capacitor includes an upper electrode, a lower electrode, and a dielectric layer interposed between the two electrodes. A plurality of electrodes is formed in parallel in the dielectric layer in a diagonal direction. First electrodes, which are half of the plurality of electrodes, are coupled to only the upper electrode, while second electrodes, which are the other half of the plurality of electrodes, are coupled to only the lower electrode. The first electrodes and the second electrodes are alternately positioned in rows and columns. The capacitor does not require additional processes, thereby reducing complexity and cost of fabrication thereof.