Electronics and Telecommunications Research Institute

Chong Ki Kwon

Jong Dae Kim

Kwi Dong Kim

Min Hyung Cho

Mun Yang Park

Young Deuk Jeon

Seung Chul Lee

Yi Gyeong Kim

Gyu Hyung Cho

Sang Heung Lee

Ja Yol Lee

Young Kyun Cho

Kyoung Ik Cho

Jin Yeong Kang

Bong Ki Mheen

Gyu Hyun Kim

Provided is a dual sampling/pixel gain amplifier (CDS/PxGA) circuit with a shared amplifier, and more particularly, to a dual CDS/PxGA circuit for adjusting a gain of an amplifier based on capacitance. The dual CDS/PxGA circuit comprises: a first sampler for sampling a reset level and a data level of a first pixel; a second sampler for sampling a reset level and a data level of a second pixel; and an operational amplifier for receiving sampling values from the first and second samplers, calculating output signals of the first and second pixels using the sampling values, and amplifying the calculated output signals. Thus, it is possible to reduce a speed of an operational amplifier by using the dual CDS/PxGA structure, reduce power consumption by sharing the operational amplifier, and obtain a variable gain of a wide range by adjusting capacitance using a capacitor array.

Dual CDS/PxGA circuit for adjusting gain of an amplifier based on capacitance

Provided are a dynamic element-matching method, a multi-bit Digital-to-Analog Converter (DAC), and a delta-sigma modulator with the multi-bit DAC and delta-sigma DAC with the multi-bit DAC. The dynamic element-matching method relates to preventing periodic signal components (in-band tones) from being generated from a delta-sigma modulator of a delta-sigma Analog-to-Digital Converter (ADC) and a multi-bit DAC used in a delta-sigma DAC. Unit elements are selected in a new sequence according to a simple algorithm every time that each of unit elements is selected once, and thus the unit elements are not periodically used. Consequently, it is possible to prevent in-band tones caused by a conventional Data Weighted Averaging (DWA) algorithm.

Dynamic element-matching method, multi-bit DAC using the method, and delta-sigma modulator and delta-sigma DAC including the multi-bit DAC

Provided is a high-speed asynchronous digital signal level conversion circuit converting an input signal of a first voltage level into a signal of a second voltage level. The conversion circuit is able to operate at high speed by connecting first and second nodes, at which the input signal of the first voltage level is converted to the signal of the second voltage level, to a second power source voltage of the second voltage level for fast voltage level conversion when the voltage level of the input signal is changed.

High-speed asynchronous digital signal level conversion circuit

Provided is an electrostatic discharge (ESD) protection circuit using a silicon controlled rectifier (SCR), which is applied to a semiconductor integrated circuit (IC). A semiconductor substrate has a triple well structure such that a bias is applied to a p-well corresponding to a substrate of a ggNMOS device. Thus, a trigger voltage of the SCR is reduced. In addition, two discharge paths are formed using two SCRs including PNP and NPN bipolar transistors. As a result, the ESD protection circuit can have greater discharge capacity.

Electrostatic discharge protection circuit using triple welled silicon controlled rectifier

Provided is an LC resonance voltage-controlled oscillator (VCO) used for a multi-band multi-mode wireless transceiver. In order to generate a multi-band frequency, a capacitor bank and a switchable inductor are included in the LC resonance voltage-controlled oscillator. The LC resonance voltage-controlled oscillator employs an adjustable emitter-degeneration negative resistance cell in place of tail current sources in order to compensate for non-uniform oscillation amplitude caused by the capacitor bank and prevent the degradation of a phase noise due to the tail current sources. The LC resonance voltage-controlled oscillator includes an inductor providing an inductance element partially determining the frequency of an oscillation wave; a discrete capacitor bank providing a capacitance element partially determining the frequency of the oscillation wave and being discretely determined by a control bit signal; and a discrete negative resistance cell providing a negative resistance element that is discretely determined by the control bit signal, to keep the amplitude of the oscillation wave constant.

Multi-band LC resonance voltage-controlled oscillator with adjustable negative resistance cell

A delta-sigma modulator having a first integrator for integrating an input signal; an analog-to-digital converter for converting the integrated signal into a digital signal; a delay circuit for delaying an output signal of the analog-to-digital converter; and a differential delay circuit for differentially delaying the output signal of the analog-to-digital converter. More particularly, the delta-sigma modulator has low distortion characteristics suitable for multi-bit fast operation, wherein a feedback signal is delayed by one clock period through the delay circuit and the differential delay circuit.

Multi-bit delta-sigma modulator

Provided is a multi-bit pipeline analog-to-digital converter (ADC) having a merged capacitor switching structure. In a multiplying digital-to-analog converter (MDAC) used in the multi-bit pipeline ADC, switches are connected between the bottom plates of respective differential capacitors, thereby constantly maintaining a uniform input common mode voltage regardless of an input digital code. Thus, it is possible to improve the operating speed and performance of the MDAC.

Multi-bit pipeline analog-to-digital converter having merged capacitor switching structure

A wide-band multimode frequency synthesizer using a Phase Locked Loop (PLL) is provided. The multiband frequency synthesizer includes a multimode prescaler, a phase detector/a charge pump, a swallow type frequency divider, and a switching bank LC tuning voltage-controlled oscillator having wide-band and low phase noise characteristics. The multimode prescaler operates in five modes and divides a signal up to 12 GHz. The wide-band frequency synthesizer can be used in various fields such as WLAN/HYPERLAN/DSRC/UWB systems that operate in the frequency range from 2 GHz to 9 GHz. The wide-band multimode frequency synthesizer includes a frequency/phase detector for comparing a frequency and phase of a reference high-frequency signal with a frequency and phase of a feedback high-frequency signal; a charge pump for producing an output current corresponding to the result of the comparison performed by the frequency/phase detector; a loop filter for producing an output voltage corresponding to an accumulated value of the output current of the charge pump; a voltage-controlled oscillator for generating an oscillation signal having a frequency corresponding to the output voltage of the loop filter; and a variable frequency divider for dividing an output signal of the voltage-controlled oscillator by a designated integer value, and outputting the result as a feedback signal, wherein at lease two of an amount of unit pumping charges of the charge pump, an RLC value of the loop filter, an RLC value of the voltage-controlled oscillator, and a divisor value of the variable frequency divider are controlled according to a band.

Wide-band multimode frequency synthesizer and variable frequency divider

Provided is a multi-bit pipeline analog-to-digital converter (ADC) capable of altering an operating mode. The ADC includes: a sample-and-hold amplifier (SHA) for sampling and holding an input analog voltage; an n+1 number of B-bit flash ADCs for receiving an analog signal and converting the analog signal into a digital signal to output the digital signal; an n number of B-bit multiplying digital-to-analog converters (MDACs) for converting a difference between the digital signal output from the B-bit flash ADC and the front-stage output signal into an analog signal to output the analog signal to the next stage; and a mode control circuit for generating n-bit control signals to control the B-bit flash ADC and the B-bit MDAC according to required resolution and operating frequency. In the multi-bit pipeline ADC, an operating mode is altered by controlling the number of stages in a pipeline and a signal path according to required resolution and operating frequency, so that power consumption can be minimized under the corresponding operating condition and signals can be processed in a variety of ways.

Multi-bit pipeline analog-to-digital converter capable of altering operating mode

A digital-to-analog converter (DAC) for a sigma-delta modulator is provided. The DAC has a switched capacitor structure using an operational amplifier (OP amp) and performs a function exceeding 3-level using a switching method employing only one capacitor in single ended form. Thus, DAC non-linearity caused by capacitor mismatching does not occur, and the number of output levels of the DAC is increased. Also, the DAC capacitor may be applied to a general DAC to increase the ratio of DAC output levels to capacitors.

Multi-bit sigma-delta modulator and digital-to-analog converter with one digital-to-analog capacitor

Provided is a low-reference-current generator that includes a circuit employing two feedback loops enabling it to operate even at a low voltage, has a high power supply rejection ratio (PSRR) to control power supply noise, and simply forms a voltage without a voltage-to-current converter used in a conventional general reference current generator. The reference current generator includes: a first voltage generator receiving a predetermined current and generating a first voltage that decreases as temperature increases; a second voltage generator generating a second voltage that increases as temperature increases; a first current generator generating a first current corresponding to the first voltage; a second current generator generating a second current corresponding to the second voltage; and a reference current generator receiving the first current and the second current and generating a reference current that is the sum of the first current and the second current.

Reference current generator

Provided are a low voltage differential signal driver circuit and a method for controlling the same. The differential signal driver circuit includes: a differential amplification signal generator disposed between a power supply voltage terminal and a ground terminal, and outputting first and second differential amplification signals to first and second output terminals in response to first and second differential input signals, respectively; a common mode voltage generator for generating a common mode voltage in response to DC (direct current) offset voltages of the first and second differential amplification signals; and a variable load portion for controlling a resistance between the power supply voltage terminal and the first output terminal and a resistance between the power supply voltage terminal and the second output terminal in response to the common mode voltage such that the first and second differential amplification signals have constant DC offset voltages.

Low voltage differential signal driver circuit and method for controlling the same

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.

Variable gain amplifier

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.

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Daejeon, South Korea

Chong Ki Kwon