Abstract: Provided is a transconductor circuit for compensating distortion of an output current without reducing the size of chips and operation speed characteristics. The transconductor circuit includes a main circuitry which is a differential pair with source degeneration and to which a predetermined input voltage is applied, an auxiliary circuitry which is connected to nodes of the main circuitry to compensate the distortion of the output current, a variable voltage supply which controls a depth or degree of a distortion compensation operation for the output current, and a current source which supplies the main circuitry with constant bias.

Abstract: Disclosed is a stacked variable inductors manufactured by stacking M (M?2) metal layers on a semiconductor substrate, and provides stacked variable inductors comprising, 1 to N inductors continuously connected in serial, wherein each of said inductors is formed on N (N?M) metal layers that are different each other; first and second ports each connected to the highest positioned inductor and to the lowest positioned inductor among said 1 to N inductors; and at least one MOSFET, and wherein one terminal of at least one MOSFET is connected to one of the first and second ports, and the other one is connected to one of adjacent terminals connected in serial between 1 to N inductors.

Abstract: Disclosed is a variable gain amplifier having low voltage, low distortion, high linearity and wideband operating characteristics.

Abstract: Provided is a pipelined folding analog-digital converter, the pipelined folding analog-digital converter comprising: a first sample-and-hold unit that samples and outputs a number of analog input voltages; a reference voltage generator that generates a number of reference voltages; a pre-amplifier that amplifies and outputs a number of values subtracting each reference voltage from the outputs of the first sample-and-hold unit, wherein an offset effect due to asymmetry of the amplifier is eliminated; a first folder that folds and outputs a number of outputs of the pre-amplifier; a second sample-and-hold unit that samples and outputs a number of outputs of the first folder; a second folder that folds and outputs a number of outputs of the second sample-and-hold unit; and a comparator that performs a comparison operation between the outputs of the pre-amplifier and the output values of the second folder to find a digital output value, whereby the offset caused by the device mismatch is removed, so that it is po

Abstract: An amplifier including an amplifier transistor that operates in an active region has main current flowing therethrough according to input voltage, and a linear transistor that is driven by offset positive-polarity input voltage to operate in a linear region and has auxiliary current flowing therethrough. The main current and auxiliary current are added to become output current. The offset positive-polarity voltage corresponds to the sum of AC component of the input voltage and an offset DC voltage. Here, a transistor stacked on the linear transistor is coupled to the amplifier transistor to secure the linear region operation of the linear transistor. The stacked transistor is driven by a voltage having polarity opposite to that of the input voltage.

Abstract: Disclosed is a stacked variable inductors manufactured by stacking M (M≧2) metal layers on a semiconductor substrate, and provides stacked variable inductors comprising, 1 to N inductors continuously connected in serial, wherein each of said inductors is formed on N (N≦M) metal layers that are different each other; first and second ports each connected to the highest positioned inductor and to the lowest positioned inductor among said 1 to N inductors; and at least one MOSFET, and wherein one terminal of at least one MOSFET is connected to one of the first and second ports, and the other one is connected to one of adjacent terminals connected in serial between 1 to N inductors.

Abstract: Disclosed is a CMOS variable gain amplifier. The variable gain amplifier comprises a first means for first and second differential input voltages, a second means for controlling its transconductance to generate an output current according to a control voltage, a third means for a bias voltage to generate bias current by current mirror, and to supply a stabilized bias current to the second means using the replica current, and a fourth means for generating an output voltage with a variable gain according to control voltage by its output current generated in the second means. Therefore, the present invention provides a function of controlling low distortion and high linearity in low voltage and a high-speed operation by the supply of a stabilized sharing current bias, and can control a voltage gain in a wide range by the control voltage.

Abstract: There is provided a quadrature modulation transmitter which is capable of solving several problems of the conventional transmitter while performing the same function as the heterodyne transmitter or the digital IF transmitter, in which a circuit structure is simplified and a power consumption is reduced compared with the conventional transmitter.

Abstract: An amplifier including an amplifier transistor that operates in an active region has main current flowing therethrough according to input voltage, and a linear transistor that is driven by offset positive-polarity input voltage to operate in a linear region and has auxiliary current flowing therethrough. The main current and auxiliary current are added to become output current. The offset positive-polarity voltage corresponds to the sum of AC component of the input voltage and an offset DC voltage. Here, a transistor stacked on the linear transistor is coupled to the amplifier transistor to secure the linear region operation of the linear transistor. The stacked transistor is driven by a voltage having polarity opposite to that of the input voltage.

Abstract: Disclosed is a variable gain amplifier having low voltage, low distortion, high linearity and wideband operating characteristics.

Abstract: Disclosed is a CMOS variable gain amplifier (VGA). The variable gain amplifier comprises a voltage-current converter for converting voltages of a wide input range into currents, a current shared circuit for receiving the currents from the voltage-current converter and controlling values of output currents depending on first and second control voltages, and a current-voltage converter for converting the output currents from the current shared circuit into differential voltages depending on a bias voltage in order to obtain a variable gain. The voltage amplifier having a variable gain is provided by controlling the value of the output current of the drain terminal against the gate voltage of the NMOS transistor constituting the current shared circuit. Therefore, an integrated circuit (IC) type variable gain amplifier operating a high speed at a low supply voltage can be obtained.

Abstract: The present invention is directed to a circuit capable of matching variable impedances, and implements the variable impedance matching circuit by varying an electrical length of a transmission line by means of external control signals. In the L or &pgr; type matching circuit using inductance and capacitance as lumped elements, the variable impedance matching circuit is implemented by changing impedance values of the variable inductance and variable capacitance as lumped elements which have been made to be controlled, or by changing a topology of a circuit network by external control signals. Therefore, the variable impedance matching circuit according to the present invention enables it possible to electrically control an impedance of interest from arbitrary impedances, thereby a radio frequency circuit to which the variable impedance matching circuit belongs can be controlled, and the matching circuit can be implemented with arbitrary complex loads from any RF signal sources.

Abstract: The present invention relates to a ROM division method for reducing the size of a ROM in a direct digital frequency synthesizer (DDFS), which is used to synthesize a frequency in a communication system requiring fast frequency conversion. A ROM consuming most energy in the system, a modified Nicholas architecture is brought forth to reduce the size of ROM. In this modified Nicholas architecture, a ROM is divided into coarse ROM and fine ROM to convert phase to sine value. The present invention divides the coarse ROM and the fine ROM into quantized ROM and error ROM respectively. Then, value stored in each ROM is segmented in certain intervals and the minimum quantized value in each of the section is stored in the quantized ROM, while the difference between the original ROM value and the quantized ROM value is stored in the error ROM. This way, the size of a ROM can be reduced. Phase value inputted in a DDFS, a sine value is calculated by adding the four ROM values, i.e.

Abstract: An automatically gain controllable linear differential amplifier using a variable degeneration resistor is disclosed. The linear differential amplifier includes an input end, a bias current source, a load unit, a first MOS transistor and a second MOS transistor. The linear differential amplifiers of the present invention can control an amplifying gain according to an input signal and improve linearity IIP3 without needing additional power consumption caused by improving the linearity. The automatically gain controllable linear differential amplifier uses NMOS/PMOS transistor so an integration process of the amplifier can be implemented more conveniently and efficiently.

Abstract: The present invention relates to a local oscillator balun using an inverting circuit. The local oscillator balun using an inverting circuit comprises a complementary output converting circuit for amplifying a weak signal as a single signal from a local oscillator to produce two signals; a differential amplification circuit for producing two signals having a given amplitude from the two signals of said complementary output converting circuit; and an inverting circuit for inverting the two signals of the differential amplification circuit. Thus, a complementary signal having the maximum amplification and small phase difference can be produced. Therefore, the present invention can implement the maximum gain and small local oscillating leakage of the frequency mixer in a Gilbert type high frequency double balance frequency mixer.

Abstract: An automatically gain controllable linear differential amplifier using a variable degeneration resistor is disclosed. The linear differential amplifier includes an input end, a bias current source, a load unit, a first MOS transistor and a second MOS transistor. The linear differential amplifiers of the present invention can control an amplifying gain according to an input signal and improve linearity IIP3 without needing additional power consumption caused by improving the linearity The automatically gain controllable linear differential amplifier uses NMOS/PMOS transistor so an integration process of the amplifier can be implemented more conveniently and efficiently.

Abstract: The present invention relates to an integrated filter circuit for digitally controlling characteristics of inductor and capacitor to thereby produce a controlled resonant frequency. The integrated circuit includes a number of inductors being connected in series between a high frequency input node and a high frequency output node, a plurality of capacitors each connected to a connection node of said each inductors, a plurality of switches, each connected between each capacitor and a ground and a feedback control unit for controlling the switches by sensing an output signal from the high frequency output node to thereby selectively couple each capacitor to the ground through a selected switches based on the sensed output signal.

Abstract: The present invention relates to a ROM division method for reducing the size of a ROM in a direct digital frequency synthesizer (DDFS), which is used to synthesize a frequency in a communication system requiring fast frequency conversion. A ROM consuming most energy in the system, a modified Nicholas architecture is brought forth to reduce the size of ROM. In this modified Nicholas architecture, a ROM is divided into coarse ROM and fine ROM to convert phase to sine value. The present invention divides the coarse ROM and the fine ROM into quantized ROM and error ROM respectively. Then, value stored in each ROM is segmented in certain intervals and the minimum quantized value in each of the section is stored in the quantized ROM, while the difference between the original ROM value and the quantized ROM value is stored in the error ROM. This way, the size of a ROM can be reduced. Phase value inputted in a DDFS, a sine value is calculated by adding the four ROM values, i.e.

Abstract: The present invention relates to a high voltage driving circuit for preventing an transient current. The high voltage driving circuit including a non-overlap signal generator for generating the first and second non-overlap signals in response to the logic level signal, a satge for generating a first driving signal in response to the logic level signal and the first and second non-overlap signals, a pre-driving circuit which is driven in response to the first non-overlap signal and the first driving signal, and a complementary output circuit for controlling a current flowing toward the output terminal in response to the output signal of the pre-driving circuit and the second non-overlap signal.

Abstract: Disclosed is a data and clock recovery circuit possible to restore data signals and synchronizing clocks which have been distorted during transmission over the communication line, which is comprised of the following: main oscillation loop that maintains operating frequency by using the input data and a self oscillation loop that operates using reference clock embedded within multiplex communication devices when communication lines get shorted or when power is restored after an outage; loop selecting switch which selects the main oscillation loop during normal operating mode and selects the self oscillation loop when communication line shorts or when the power is being restored; data signal monitor which connects to the loop selecting switch and determines communication line shorting by monitoring data transmission; power supply monitor which connects to the loop selecting switch and monitors the restoration of power after an outage.