Abstract: There is provided a dual band receiver receiving frequency signals in different bands, the receiver including: a first down converter converting a first band signal into a first intermediate frequency signal; a second down converter converting a second band signal into a second intermediate frequency signal; a first voltage control oscillator supplying a first oscillation frequency to the first down converter; a second voltage control oscillator supplying a second oscillation frequency to the second down converter; a first filter passing the first intermediate frequency signal within a desired bandwidth; a second filter passing the second intermediate frequency signal within a desired bandwidth; and a clock generator converting the first oscillation frequency of the first voltage control oscillator into sampling frequencies corresponding to integer multiples of first and second oscillation frequencies and supplying the sampling frequencies to first and second AD converters, respectively.

Abstract: A mixer with a differential DC offset cancellation function includes: a load unit including a first load unit and a second load unit; a mixing unit biased by current transferred from the load unit to mix inputs signal and oscillation signals; a first output voltage detection unit detecting an output voltage of the first output terminal; a second output voltage detection unit detecting an output voltage of the second output terminal; a first injection/extraction circuit unit injecting current into the first load unit or extracting current from the first load unit according to the size of a first detection voltage; a second injection/extraction circuit unit injecting current into the second load unit or extracting current from the second load unit according to the size of a second detection voltage; and a current regulation unit regulating an overall current flowing across the first and second injection/extraction circuit units.

Abstract: An active balun with a stacked structure includes: a first amplification unit including a first transistor having a first terminal connected with a first input terminal, a second terminal connected with a power voltage terminal, and a third terminal connected with an output terminal; a second amplification unit including a second transistor having a first terminal connected with a second input terminal, a second terminal connected with the output terminal, and a third terminal connected with a ground; and a capacitance matching unit connected between the first terminal and the third terminal of the first transistor and having a pre-set matching capacitance.

Abstract: The present invention relates to and auto frequency calibrator, a method thereof, and a frequency synthesizer using it. The auto frequency calibrator includes a capacitor bank selector that is operated as an open loop and compares a frequency signal having integer-divided reference frequency with the reference frequency signal to select a capacitor bank corresponding to an output frequency; and a capacitor bank controller that is operated as a closed loop when the capacitor bank is selected and compares the output voltage corresponding to the output frequency with a preset voltage range to control the capacitor bank selected in the capacitor bank selector.

Abstract: Disclosed is a step variable gain amplifier for linearly amplifying a signal received from an antenna. The step variable gain amplifier includes: an amplification unit for converting and amplifying a voltage component of a received signal into a current voltage according to a step amplification control signal; a controller for generating a step amplification control signal of the received signal and controlling on/off of the amplification unit according to the control signal; and an output unit connected to the amplification unit, the output unit outputting a voltage component from the signal that has been subjected to conversion into the current component and amplification processes.

Abstract: The present relates to a fractional-N frequency synthesizer improving noise characteristics and a method thereof.

Abstract: There is provided a wide-band amplifier circuit with improved gain flatness. The wide-band amplifier circuit includes a first resonant load unit connected to an operating power terminal, providing a preset first load, and forming a preset first resonant point, a second resonant load unit connected to the operating power terminal, providing a preset second load, and forming a second resonant point set to a frequency different from the first resonant point; a first amplification unit receiving operating power via the first load of the first resonant load unit, having an amplification band characteristic determined according to the first resonant point of the first resonant load unit, and amplifying an input signal; and a second amplification unit receiving operating power via the second load, having an amplification band characteristic determined according to the second resonant point, and amplifying an input signal from the first amplification unit.

Abstract: There is provided a feedback circuit including: an oscillator generating an oscillation frequency signal; a mixer unit having an input terminal, a feedback terminal, and an output terminal and outputting a frequency signal through the output terminal, the frequency signal obtained by adding or subtracting frequency of a feedback signal, input through the feedback terminal, to or from frequency of the oscillation frequency signal input through the input terminal from the oscillator; a first frequency divider dividing the frequency signal output from the mixer unit at a division ratio of N (N is a multiple of 2) to generate an output signal; and a feedback circuit adjusting the output signal of the first frequency divider for the first frequency divider to output a frequency signal in a desired band and feeding back the adjusted signal to the feedback terminal of the mixer unit.

Abstract: A buffer amplifier has high input impedance and is less affected by temperature by supplying independent bias power to each of amplification units. The buffer amplifier includes a bias supply unit supplying bias power having a preset voltage level, an amplification unit receiving preset driving power and the bias power from the bias supply unit to amplify an input signal, and a compensation unit compensating for current unbalance of the driving power supplied to the amplification unit.

Abstract: There is provided a frequency divider using a latch structure including: a first latch sampling and latching an input signal in response to a first clock signal and a second clock signal having an inverse phase with respect to the first clock signal; a second latch toggled with the first latch, the second latch sampling and latching the input signal in response to the first and second clock signals; a bias adjustor generating a sampling bias current and a latching bias current to supply to the first and second latches, respectively and adjusting a relative ratio between the sampling bias current and the latching bias current to vary a minimum power point oscillating frequency of the first and second latches.

Abstract: There is provided an active balun circuit including: a load circuit unit including a first and a second load; a differential amplifying unit including a first amplifying unit connected to the first load, and a second amplifying unit connected to the second load and forming a differential amplifying unit together with the first amplifying unit, the differential amplifying unit differentially amplifying an input signal, and outputting first and second output signals out-of-phase with each other through first and second output terminals, respectively; a current source connected between a ground and a common connection node of the first and second amplifying units, and maintaining a constant amount of current flowing through the differential amplifying unit; and a compensation amplifying unit amplifying the input signal supplied through the input terminal, transmitting the amplified input signal to the second amplifying unit, and rejecting common mode noise of the differential amplifying unit.

Abstract: There is provided a bias current generating apparatus capable of providing a bias current where a characteristic change is compensated, to one of an analog circuit and RF circuit where various characteristic changes occur according to a temperature, by generating bias currents having a plurality of temperature coefficients.

Abstract: A derivative superposition circuit for linearization includes a first active element that is provided with first to third terminals and in which the magnitude and direction of current flowing from the second terminal to the third terminal changes on the basis of the magnitude of a voltage applied between the first and second terminals; and a second active element that is provided with first to third terminals and has complementary characteristics with the first active element. The first terminals of the first and second active elements are connected to each other so that a predetermined operational bias voltage is maintained by first and second power supplies through a first impedance, and are connected to an input end through a second impedance. The third terminals of the first and second active elements are connected to an output end, and the second terminals of the first and second active elements are connected to the second power supply through a third impedance.

Abstract: There is provided a feedback circuit including: an oscillator generating an oscillation frequency signal; a mixer unit having an input terminal, a feedback terminal, and an output terminal and outputting a frequency signal through the output terminal, the frequency signal obtained by adding or subtracting frequency of a feedback signal, input through the feedback terminal, to or from frequency of the oscillation frequency signal input through the input terminal from the oscillator; a first frequency divider dividing the frequency signal output from the mixer unit at a division ratio of N (N is a multiple of 2) to generate an output signal; and a feedback circuit adjusting the output signal of the first frequency divider for the first frequency divider to output a frequency signal in a desired band and feeding back the adjusted signal to the feedback terminal of the mixer unit.

Abstract: There is provided a dual band receiver receiving frequency signals in different bands, the receiver including: a first down converter converting a first band signal into a first intermediate frequency signal; a second down converter converting a second band signal into a second intermediate frequency signal; a first voltage control oscillator supplying a first oscillation frequency to the first down converter; a second voltage control oscillator supplying a second oscillation frequency to the second down converter; a first filter passing the first intermediate frequency signal within a desired bandwidth; a second filter passing the second intermediate frequency signal within a desired bandwidth; and a clock generator converting the first oscillation frequency of the first voltage control oscillator into sampling frequencies corresponding to integer multiples of first and second oscillation frequencies and supplying the sampling frequencies to first and second AD converters, respectively.

Abstract: There is provided a step attenuator having two Pi-type attenuators and one bridged-T type attenuator that share some resistors. The step attenuator is used to prevent a reduction in frequency range caused by use of MOS transistors and reduce attenuation of signal power and frequency band by the MOS transistors, thereby obtaining a low attenuation value and reducing input and output mismatch.

Abstract: A received signal strength indicator according to an aspect of the invention may include a gain calibration section including a calibration limiter, a calibration load unit and a comparison and adjustment unit. The calibration load unit is connected to output terminals of the calibration limiter, and generating an output differential voltage whose gain is a unit gain when a predetermined input differential voltage is input to the calibration limiter, and a comparison and adjustment unit comparing the input differential voltage with the output differential voltage, and adjusting an output of a variable current source included in the calibration limiter so that the input differential voltage becomes identical to the output differential voltage.

Abstract: There is provided an active balun circuit including: a load circuit unit including a first and a second load; a differential amplifying unit including a first amplifying unit connected to the first load, and a second amplifying unit connected to the second load and forming a differential amplifying unit together with the first amplifying unit, the differential amplifying unit differentially amplifying an input signal, and outputting first and second output signals out-of-phase with each other through first and second output terminals, respectively; a current source connected between a ground and a common connection node of the first and second amplifying units, and maintaining a constant amount of current flowing through the differential amplifying unit; and a compensation amplifying unit amplifying the input signal supplied through the input terminal, transmitting the amplified input signal to the second amplifying unit, and rejecting common mode noise of the differential amplifying unit.

Abstract: There is provided a step attenuator having two Pi-type attenuators and one bridged-T type attenuator that share some resistors. The step attenuator is used to prevent a reduction in frequency range caused by use of MOS transistors and reduce attenuation of signal power and frequency band by the MOS transistors, thereby obtaining a low attenuation value and reducing input and output mismatch.

Abstract: There is provided a bias current generating apparatus capable of providing a bias current where a characteristic change is compensated, to one of an analog circuit and RF circuit where various characteristic changes occur according to a temperature, by generating bias currents having a plurality of temperature coefficients.