Abstract: A mixer circuit having improved linearity and noise figure is disclosed.

Abstract: Disclosed herein is an amplifier circuit having improved linearity and frequency band using a MGTR. The amplifier circuit comprises an amplification unit including a main transistor and an auxiliary transistor, an attenuation unit including inductors respectively connected to the source of the main transistor and the source of the auxiliary transistor, a capacitor connected at one end thereof to the sources of the main transistor and auxiliary transistor and connected at the other end thereof to the gates of the main transistor and auxiliary transistor, and an output unit connected to the drains of the main transistor and auxiliary transistor.

Abstract: Disclosed herein is a circuit for generating reference current. The circuit for generating reference current comprises a current providing unit for generate a PTAT current, mirroring the PTAT current to generate an analogous PTAT current and generate an analogous BGR current, a current ratio control unit for generating an analogous BGR current in a first ratio, a PTAT current in a second ratio, and a current corresponding to the difference between the analogous PTAT current in the second ratio and the analogous BGR current in the first ratio, and a current increasing/decreasing unit for generating a BGR current in the first ratio.

Abstract: A mixer circuit with improving characteristic of image rejection by compensating mismatch in a spurious rejection mixer circuit (SRM) used in a transmitter is provided. The mixer circuit according to the present invention comprises an up conversion unit for modulating a base-band input signal to a RF signal, a down conversion unit for converting an output signal from the up conversion unit to a base-band output signal, mismatch estimating means for determining a mismatch compensation value by which spurious component in an output signal from the down conversion unit is minimized, wherein the spurious component results from mismatch in the up conversion unit, and mismatch compensating means for compensating the mismatch in the up conversion unit by using the mismatch compensation value determined by the mismatch estimating means.

Abstract: A local oscillator provides an in-phase local oscillating signal and quadrature-phase signal to first and second mixers outputting an input signal with a mixed in-phase local oscillating signal and quadrature-phase local oscillating signal, respectively. The oscillator comprises a local oscillator having first and second delay cells and outputting said in-phase local oscillating signal and said quadrature-phase local oscillating signal; and a correction circuit for controlling phase matching characteristics, said correction circuit setting bias current flowing in said first and second delay cells of said local oscillator as being to be different. In another embodiment, the phase matching characteristic is controlled by setting the bias voltage applied to the first and second delay cells as being to be different, by setting the width of the active device included in the first and second delay cells dells as being to be different, or by setting impedance of passive device to be different.

Abstract: The present invention relates to a harmonic circuit for improving linearity, the harmonic circuit according to the present invention comprises a first terminal connected to a collector of a NPN transistor and a second terminal connected to an emitter of the NPN transistor, and removes inter-modulation noise from the signal appeared at the collector of the NPN transistor. The harmonic circuit includes a PNP transistor, a first resistor, and a second resistor. The PNP transistor generates harmonic components without affecting the main signal, and the harmonic components that are generated by the PNP transistor compensate the harmonic components that are generated by the NPN transistor by having load of different sign from the load of the harmonic components that are generated by the NPN transistor.

Abstract: The present invention relates to improvement of even order distortion noise, DC offset, and non-linearity of mixer circuits. According to the present invention, a mixer circuit is provided, which comprises a splitter for splitting an input signal to the first and second signal having phase difference of 180 degree, a local oscillator, first mixer for mixing the first signal with the local oscillation signal, second mixer for mixing the second signal with the local oscillation signal, and subtractor for subtracting the output of the second mixer from the output of the first mixer.

Abstract: An image rejection mixer (IRM) for rejecting signals having image frequency and, more particularly, a mixer for rejecting signals of image frequency by using mismatch compensation is provided. The image rejection mixer comprises: first and second mixers; first and second converting means, each of which transforms each output of the first and second mixers to digital signal; third and fourth mixers, each of which mixes output of the first converting means with each of second local oscillation in-phase signal and quadrature-phase signal, respectively; fifth and sixth mixers, each of which mixes output of the second converting means with each of second local oscillation in-phase signal and quadrature-phase signal, respectively; means for subtracting; means for adding; and means for compensating gain-mismatch between the first and second mixers.

Abstract: The present invention is to provide a charge pump circuit for improving switching speed and compensating mismatch between a source and a sink currents flowing to output terminal. A charge pump circuit according to the first embodiment of the present invention comprises a first and second switching elements, a discharging and charging elements, a biasing unit, a first and second compensating unit, a charge pumping unit, a current mirror unit, a control unit, and a biasing unit. The compensating circuit removes the deterioration owing to the parasitic capacitance, and the control circuit controls the charge that is flowed or emitted from the parasitic capacitance. A charge pump circuit according to the second embodiment of the present invention comprises a charge pumping unit, a current mirror unit, a control unit a biasing unit. The charge pump circuit decects the mismatch between the output currents via the control unit, and compensates the mismatch by the biasing unit.

Abstract: The present invention relates to a circuit for varying bandwidth of transconductance-capacitor filter by controlling transconductance of a transconductance circuit, and a digital tuning circuit of transconductor-capacitor filter. A transconductor of an embodiment of the present invention comprises a first and second amplifying devices; a resistor; a first and second bias current sources; and transconductance varying circuit. A tuning circuit of another embodiment of the invention relates to a digital tuning circuit comprising a transconductor that outputs current proportional to input voltage and a varying capacitance that is connected with output node of transconductor and between grounds and varies its capacitance depending upon the level of control signal.

Abstract: The present invention is related to a variable gain low noise amplifier that optimizes input matching, gain and noise characteristics, and linearity. The variable gain low noise amplifier according to an embodiment of the present invention includes a first amplifying cell that operates in a high gain mode, a second amplifying cell that operates in a low gain mode, a selectively matching circuit, and a first short-circuit means. The variable gain low noise amplifier according to the present invention selects the best operation in each gain mode so that the circuit operated in high and low gain modes does not affect a load of another circuit.

Abstract: The present invention relates to a circuit for varying bandwidth of transconductance-capacitor filter by controlling transconductance of a transconductance circuit, and a digital tuning circuit of transconductor-capacitor filter. A transconductor of an embodiment of the present invention comprises a first and second amplifying devices; a resistor; a first and second bias current sources; and transconductance varying circuit. A tuning circuit of another embodiment of the invention relates to a digital tuning circuit comprising a transconductor that outputs current proportional to input voltage and a varying capacitance that is connected with output node of transconductor and between grounds and varies its capacitance depending upon the level of control signal.

Abstract: Disclosed is a wideband variable gain amplifier with high linearity that operates in a switch mode. The variable gain amplifier includes a first amplifier unit, a second amplifier unit and a third amplifier unit. The first amplifier unit includes an amplifier, a wideband-matching element, an attenuator and first switching means. The first amplifier unit supports a high gain mode operation and a low gain mode operation. In the high gain mode, the first switching means is short-circuited and an input signal is amplified with a high gain. It is thus possible to reduce noise characteristics of the entire system by a rear stage. In the low gain mode, the first switching means is opened and the input signal is attenuated by the attenuator without an amplification operation. It is thus possible to reduce a non-linearity occurring by the rear stage of the first amplifier unit.

Abstract: The present invention relates to a circuit for varying bandwidth of transconductance-capacitor filter by controlling transconductance of a transconductance circuit, and a digital tuning circuit of transconductor-capacitor filter. A transconductor of an embodiment of the present invention comprises a first and second amplifying devices; a resistor; a first and second bias current sources; and transconductance varying circuit. A tuning circuit of another embodiment of the invention relates to a digital tuning circuit comprising a transconductor that outputs current proportional to input voltage and a varying capacitance that is connected with output node of transconductor and between grounds and varies its capacitance depending upon the level of control signal.

Abstract: The present invention relates to circuits having differential structure which uses complementary devices for processing single-ended signal. The single-ended differential circuit in accordance with the present invention, comprises first and second complementary devices having first, second, and third terminals, respectively, wherein current flowing from the second terminal to the third terminal has its quantity and direction being varying in dependant on the voltage driven to the first terminal, wherein the currents flowing through the first and second complementary devices vary in opposite relationship.

Abstract: A broadband variable gain amplifier with improved linearity and gain characteristic is provided. According to the present invention, the broadband variable gain amplifier comprises: an amplification unit for amplifying an input signal applied to an input terminal and outputting an amplified signal to an output terminal; and a gain control unit which is connected between the input and output terminals, and for controlling gain of said amplification unit, wherein said gain control unit comprises: a variable resistance unit whose resistance value is varied according to a control signal; and a broadband matching unit for proving an optimal impedance characteristic to the input terminal said amplification unit in a broad band, where in said variable gain resistance unit and said broadband matching unit is connected in parallel.

Abstract: The present invention relates to the improvement of a phase noise characteristics of supply voltage in VCO. The delay in delay cells may be controlled to use the resistor of a transmission gate instead of a tail current. That is, the delay of cells is controlled by applying the overdrive voltage in transmission gate. And the self-regulating may be possible to composing a feedback inside the delay cells.

Abstract: The present invention relates to improvement of gain slope characteristic and linearity of a variable gain amplifier.

Abstract: The present invention relates to circuits having differential structure which uses complementary devices for processing single-ended signal. The single-ended differential circuit in accordance with the present invention, comprises first and second complementary devices having first, second, and third terminals, respectively, wherein current flowing from the second terminal to the third terminal has its quantity and direction being varying in dependant on the voltage driven to the first terminal, wherein the currents flowing through the first and second complementary devices vary in opposite relationship.

Abstract: A signal processing apparatus for correcting DC offset in a communication system is provided.