Abstract: A low noise amplifier (LNA) for ultra wide band receives 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 multi-input multi-frequency synthesizing apparatus and method for a multi-band radio frequency (RF) receiver. The frequency synthesizing apparatus may generate an output from a greater number of high frequency signals by using one multi-input single side band (SSB) mixer. The multi-input SSB mixer may generate a signal whose frequency is an addition of frequencies of two signals selected from a signal selection control unit, or a difference of frequencies therebetween. According to a circuit configuration of the multi-input SSB mixer, the signal selection control unit may select more than two signals.

Abstract: An apparatus and method for frequency synthesis using a Delay Locked Loop (DLL) are provided. The apparatus includes the DLL, an edge pulse generator, and an inductive-capacitive (LC) tank switch. If phases of a reference frequency signal and a feedback signal are the same and thus are locked, the DLL delays the reference frequency signal. The edge pulse generator generates a plurality of pulse signals representing phase delay amounts of signals. The LC tank switch combines the plurality of pulse signals and generates frequency.

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 receiver apparatus for tracking and rejecting a Transmit (Tx) signal in a wireless communication system and an operation method thereof are provided. The receiver apparatus includes a controller for receiving channel frequency information of the Tx signal and for controlling an operation for tracking and rejecting a frequency of the Tx signal; a phase locked loop for generating an oscillation frequency by generating a control voltage according to the channel frequency information of the Tx signal under the control of the controller and for filtering a signal corresponding to the oscillation frequency among signals input to a low noise amplifier; and the low noise amplifier for amplifying power while minimizing noise of a signal filtered by the phase locked loop.

Abstract: A low noise amplifier (LNA) for ultra wide band receives 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 low-noise amplification apparatus and method in a receiver in a wireless communication system are provided, in which a main amplifier amplifies a received signal, a sub-amplifier amplifies a third-order harmonic component more strongly than a signal component in the received signal and cancels the third-order harmonic component by combining the amplified signal with the signal received from the main amplifier. A noise eliminator amplifies noise included in the received signal and eliminates the noise by combining the amplified noise with the signal received from the main amplifier or the signal received from the sub-amplifier.

Abstract: A frequency synthesizing apparatus and method for a multi-band radio frequency (RF) receiver is provided. The frequency synthesizing apparatus includes a simple circuit configuration with a single SSB mixer and thus, may synthesize six high frequency signals. Signals to be inputted into the SSB mixer include a first signal and a second signal. The first signal is generated based on a VCO and a PPF. Also, the second signal is selected from a plurality of frequency divided signals which are generated by dividing a signal generated in the VCO via a plurality of dividers.

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 phase-locked loop (PLL) for stably adjusting a frequency band of a voltage-controlled oscillator and a phase locking method. In the PLL, a frequency band controller alters the frequency band selection digital value in response to an input clock signal and an oscillation control signal generated from an LPF of a basic PLL circuit, and thus a voltage-controlled oscillator of the basic PLL circuit alters the frequency of an output clock signal in response to the oscillation control signal and the frequency band selection digital value. The output clock signal is rapidly and stably phase-locked at a target frequency depending on the frequency band selection digital value.

Abstract: An apparatus and method of reducing a flicker noise of a CMOS amplifier is provided. In the CMOS amplifier, a load circuit is connected to a signal input circuit which includes two pairs of MOSFETs which simultaneously receive differential signals. In this instance, a first MOSFET included in a switch-bias circuit is connected to one pair of MOSFETs which receive the differential signals and functions as a current source in the case of activation of a clock signal Ø1. A second MOSFET included in the switch-bias circuit is connected to another pair of MOSFETs which receive the differential signals and functions as a current source in the case of activation of a clock signal Ø2.

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 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 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 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: 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: 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 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: 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: The differential amplifier and an active load are provided. The differential amplifier includes a differential input section which is configured to generate a differential current according to a differential input signal; and an active load which is configured to generate a differential output signal according to the differential current. The active load includes first and second active load sections comprising a first negative feedback loop and a second negative feedback loop, respectively; and a common mode feedback section comprising a feedback current source which supplies a feedback current to the first active load section and the second active load section to form a common mode feedback path.