Electronics and Telecommunications Research Institute

Korea Telecom

Sam Jung Co., Ltd.

Alphachips Corp.

Ook Kim

Jong-Kee Kwon

Won-Chul Song

Jong-Ryul Lee

Chang-Jun Oh

Jong Ryul Lee

Kyung Soo Kim

Kyung-Soo Kim

Jong Kee Kwon

Won Chul Song

Chang Jun Oh

Sung Ho Lee

Han Jin Cho

Hee Bum Jung

Seong I Jang

Min H Song

Dong S Kim

Gyu-Dong Kim

Moon Yang Park

Jaewoo Park

Jae K Chong

The present invention provides a circuit for generating a bias voltage for a high speed input/output pad. To this end, a bias voltage generator according to an embodiment of the present invention is to supply at least one bias voltage to a buffer circuit connected to the pad, which includes: a bias generation part for generating a first bias voltage; and a reference voltage generation part for generating a voltage proportional to the pad voltage applied to the pad as a reference voltage, wherein the first bias voltage may be the sum of the reference voltage and a predetermined voltage.

Circuit for generating bias voltage for high speed input/output pad

The present invention relates to a tuning circuit, more specifically to a tuning circuit for continuous-time filter capable of making exact the Gm value to minimize the variation of the cutoff frequency due to the variation of process in the Gm-C type of continuous-time filter. According to the invention, a frequency tuning circuit is provided which comprises integrating means for generating a signal discharging from a first reference voltage to a first predetermined value and a signal charging from a second reference voltage to a second predetermined value; offset sampling means for sampling the offset voltages of the Gm cells by receiving a current multiplied by the offset voltages from the Gm cells included in the integrating means and providing a feedback path between the output nodes and the input nodes of the included Gm cells; comparative signal generating means for generating a comparative signal by generating a reference signal by dividing a clock inputted from the external, receiving the signal discharging from the first reference voltage to the first predetermined value and the signal charging from the second reference voltage to the second predetermined value from the integrating means, and comparing the actual intersection and the target intersection of these signals; and control means for generating a control signal to regulate the Gm values of the integrating means and the offset sampling means by receiving the reference signal and the comparative signal from the comparative signal generating means and detecting the phase differences therebetween.

Low offset automatic frequency tuning circuits for continuous-time filter

The present invention discloses a mixer using a replica voltage-current converter, and more particularly a mixer using the replica voltage-current (V-I) converter of the present invention, which feedbacks the output current of the replica voltage-current converter using an additional amplifier so as to improve the linearity thereof by the gain of the amplifier because the conventional mixer operating at a high speed dissipates a lot of electrical power to have low output impedance.

Mixer using replica voltage-current converter

There is disclosed a low frequency filter. A low frequency cutoff filter includes a filter circuit having a capacitor connected between an input terminal and an output terminal and an active resistor connected to the output terminal, having a very large resistance, and a bias circuit having a negative feedback to set a biasing voltage of the active resistor to a desired value, thereby implementing the cutoff filter within a semiconductor chip as one set with the capacitor having a small capacitance. A low frequency pass filter includes an active resistor having a very large resistance, means for setting a biasing voltage of the active resistor to a desired value, and a capacitor connected between the output terminal and the ground. Therefore, the low pass filter can be integrated-circuited using even small capacitor.

Low pass filter

A double mode modulator, particularly, for a portable telephone, which is adapted to realize both digital and analog modulations and have a low phase noise and a reduced locking time with a device readily integrated in an integrated circuit, including: a frequency synthesizer for synthesizing a particular frequency from an external reference clock signal; a digital modulator for performing a quadrature modulation for an output signal of the frequency synthesizer; and an analog modulator for performing a frequency modulation for the output signal of the frequency synthesizer.

Double mode modulator

A CMOS offset trimming circuit and offset generation circuit for obtaining the corrected optimum offset value for correcting the offset generated in the CMOS analog circuit. An offset trimming circuit comprises a flip-flop for loading a data to be used for obtaining an optimum offset value or a data to be trimmed according to an input clock, a fuse circuit for setting the circuit with a corrected optimum offset value obtained in a corresponding mode by receiving the data loaded on the flip-flop and the mode selection signal as an input signal, and a selection logic circuit for outputting a selected signal as a trimming output signal by selecting one from the group consisting of the data loaded on the flip-flop and the data output from the fuse circuit according to the operation mode.

CMOS offset trimming circuit and offset generation circuit

An integrated circuit built-in type power delay circuit which is capable of supplying a stable supply power to each circuit of the integrated circuit by generating a supply power control signal voltage after a predetermined time. The circuit includes a receiving unit for receiving a supply voltage VDD and charging the same, a supplying unit for supplying a current, an inverting unit for inverting an output value from the charging unit, a switching unit controlled in accordance with an output value from the inverting unit for switching an output from the current supply unit, a current regenerating unit for receiving a control of the switching unit and discharging an output value from the charging unit, an electric potential value conversion unit controlled by an output value from the inverting unit for converting an output value from the charging unit into a low level, and a buffering unit for receiving an output value from the inverting unit for buffering the output value and outputting a non-inverted signal.

Integrated circuit built-in type supply power delay circuit

The digital logic level conversion circuit is for converting a small sinusoidal signal or an unbalanced digital signal to a balanced digital signal with 50% duty ratio, and includes an input level shift circuit, two differential amplifiers, an RS flip-flop, a charge-pump circuit, and a bias circuit. The input level shift circuit for AC coupling a sinusoidal wave with a small amplitude (with a minimum of 0.4 Vpp) and converting it into a middle logic level. The two differential amplifiers is used as comparators having hysteresis each other, operates inversely, and outputs digital signals into the RS flip-flop; the bias circuit for controlling a driving current of the differential amplifiers; the RS flip-flop for driving the charge-pump circuit by outputting a digital signal upon receiving outputs from the differential amplifiers; and the charge-pump circuit for generating a reference potential level of the differential amplifiers.

Digital logic level conversion circuit with a small sinusodal wave input

A voltage control oscillation circuit for a CMOS which is capable of reducing phase noise and power consumption by adapting a voltage amplitude control loop and a common mode feedback circuit to a conventional LC-tank circuit. The circuit includes an LC-tank oscillation unit for outputting an oscillation voltage, an output common mode feedback unit for receiving an output from the LC-tank oscillation unit and eliminating a common mode noise of the output, and a voltage amplitude control unit for controlling a bias current of the LC-tank oscillation unit in accordance with a voltage difference at both ends of an LC-tank oscillation terminal which voltage is applied thereto through the output common mode feedback unit, for thus controlling the amount of an oscillation voltage.

Voltage control oscillation circuit using CMOS

A digital-to-analog (D/A) converter of current segmentation is disclosed. A plurality of current sources are connected in parallel to one another and connected to a load resistance through a plurality of first switches. A second switch is connected in parallel to the first switches and operates oppositely to the first switches. An output impedance compensation resistance is connected in series to the second switch.

Digital-to-analog converter of current segmentation

A method for autofocusing a video camera, adjusting the focus by defining the focus range in which the contrast signal is extracted, generating the control clock pulse having higher frequencies than the video signal during the occurrence period of horizontal and vertical synchronizing signals corresponding to the focus range, sampling the video signals obtained in the image pick-up elements by means of the control clock pulses, converting this sampled signal into digital signal, generating the digital differential signal which represents the difference between the values of one control clock pulse earlier one and current one, producing the digital weighted signal by transforming the digital differential signal by means of the nonlinear weight value, integrating the digital weighted signals for one or more fields or frames to obtain the focusing value, and moving the focusing lensd based on the focusing value to the location where the focusing value approximately reaches the maximum.

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Seoul, South Korea

Ook Kim