Search results for: Choon Sik Cho

Items from 1 to 20 out of 64 results

article

PLL-based electrical balance CMOS integrated duplexer with hybrid transformer

Yeong Seok Choi, Choon Sik Cho, Young-Jin Kim

Analog Integrated Circuits and Signal Processing > 2019 > 99 > 3 > 669-677

This paper describes the design of an integrated duplexer with electrical balance network using the phase locked loop (PLL) for impedance variation tracking. The hybrid transformer is devised for blocking the transmitted signal leaking to the receiver. We suggest a method of impedance tracking based on PLL system, which can maintain high isolation between the transmitter and the receiver. The PLL...

article

Active balun using resistive feedback for low gain imbalance

Yeong Seok Choi, Ho Jeong Jin, Choon Sik Cho, Young‐Jin Kim

Microwave and Optical Technology Letters > 60 > 3 > 609 - 614

An active balun using current steering topology is presented for phase and amplitude corrections. The proposed active balun is constructed with two different unit balun structures based on resistive feedback to reduce phase and amplitude errors. The first unit balun composed of the common source configuration provides a main transconductance stage for the proposed active balun. The second unit balun...

article

Zigbee transmitter using a low‐power high‐gain up‐conversion mixer

Ho Jeong Jin, Yeong Seok Choi, Choon Sik Cho, Young‐Jin Kim

Microwave and Optical Technology Letters > 60 > 1 > 277 - 280

This article introduces a direct‐conversion CMOS RF transmitter for the IEEE 802.15.4 standard with a low‐power high‐gain up‐conversion mixer designed in 0.18 μm process. The designed RF direct‐conversion transmitter (DCT) is composed of differential digital to analog converter, passive lowpass filter, quadrature active mixer, and drive amplifier. The most important characteristic in designing RF...

article

Multiband multistandard frequency synthesizer for mobile TV tuner with LC‐VCO by digital AAC

Jae Kyung Lee, Young‐Jin Kim, Choon Sik Cho

Microwave and Optical Technology Letters > 58 > 8 > 1838 - 1841

To improve the phase noise (PN) degradation from the tail current source, this article presents an inductor‐capacitor voltage‐controlled oscillator (LC‐VCO) with digitally controlled programmable low drop out. The digital automatic amplitude calibration (AAC) loop is successively implemented to make the voltage swing constant over 900–1940 MHz. A 40–970 MHz frequency synthesizer with switching dividers...

article

Wideband high-isolation SPDT RF switch in 0.18- $$\upmu$$ μ m SiGe BiCMOS technology

Byeong Wan Ha, Chang Won Seo, Choon Sik Cho, Young-Jin Kim

Analog Integrated Circuits and Signal Processing > 2016 > 87 > 1 > 11-19

A single pole double throw (SPDT) RF switch working in wide band is presented. The SPDT RF switch composed of many single pole single throw (SPST) switches changes the signal flow corresponding to control signals. It is very important to obtain low insertion loss and high power driving capability for dealing with the input signal of wide dynamic range. High isolation is also desirable for suppressing...

chapter

A low power RF CMOS direct-conversion transmitter using high conversion gain front end for IEEE 802.15.4 standard

Changwon Seo, Hanjin Cho, Seyoung Baik, Jinyong Kim, more

2015 International SoC Design Conference (ISOCC) > 21 - 22

2015 International SoC Design Conference (ISOCC)

This paper introduces a direct conversion transmitter for IEEE 802.15.4 applications with a high gain up-conversion mixer. An RF DCT (Direct Conversion Transmitter) is composed of differential-ended DAC (Digital to Analog Converter), passive low pass filter, quadrature active mixer, and drive amplifier. The most important thing in designing RF direct conversion transmitter is satisfying 2.4GHz Zigbee...

chapter

Energy transfer and harvesting for RF-Bio applications — Invited

Byeong Wan Ha, Ji An Park, Ho Jeong Jin, Choon Sik Cho

2015 IEEE MTT-S 2015 International Microwave Workshop Series on RF and Wireless Technologies for Biomedical and Healthcare Applications (IMWS-BIO) > 54 - 55

2015 IEEE MTT-S 2015 International Microwave Workshop Series on RF and Wireless Technologies for Biomedical and Healthcare Applications (IMWS-BIO)

Biomedical systems using microwave technology consume electric energy depending upon their applications. Those systems are deployed inside or outside living bodies. Energy can be supplied through wireless power transfer to the injected biomedical devices from outside, or can be harvested using various technologies such as RF, heat and vibration. For bio-systems or devices deployed outside living bodies...

article

New Design Formulas for Asymmetric Coupled-Section Marchand Balun

Jeong Hun Lee, Ji An Park, Choon Sik Cho, Jae W. Lee

IEEE Microwave and Wireless Components Letters > 2015 > 25 > 7 > 448 - 450

Design formulas for the asymmetric coupled-section Marchand balun are derived. The characteristic impedance, port impedance and electrical length of asymmetrical coupled transmission lines across two layers comprise the design formulas for designing the Marchand balun. A Marchand balun is realized based on the deduced design formulas using two identical asymmetrical coupled transmission lines fabricated...

article

A CMOS UWB OOK pulse generator with multiple pulses per bit

Yoon Jae Bae, Choon Sik Cho, Young‐Jin Kim

Microwave and Optical Technology Letters > 57 > 5 > 1177 - 1179

This letter demonstrates a CMOS impulse radio ultrawideband (IR‐UWB) on–off keying (OOK) generator with multipulses per bit generation. The proposed IR‐UWB OOK generator is implemented in 0.11 μm CMOS process where 1.33 mm² proto‐type accomplishes pulse train of 250 Mbps for one bit duration while consuming 10 mW from 1 V supply voltage. This pulse generator complies with the FCC spectral mask for...

chapter

Ultra-wideband on-off keying transmitter with multi-pulses/bit for bio-signal detectors

Yoon Jae Bae, Choon Sik Cho

2014 IEEE MTT-S International Microwave Workshop Series on RF and Wireless Technologies for Biomedical and Healthcare Applications (IMWS-Bio2014) > 1 - 3

2014 IEEE MTT-S International Microwave Workshop Series on RF and Wireless Technologies for Biomedical and Healthcare Applications (IMWS-BIO)

This paper describes an IR-UWB OOK transmitter with multi-pulses per bit for bio-signal detectors which can be transplanted into the living body. The proposed IR-UWB OOK transmitter is implemented in 110 nm CMOS process where 1.33 mm² proto-type accomplishes a maximum pulse rate of 250 Mbps while consuming 11 mW from 1 V supply voltage. It consists of impulse generator, LC oscillator, delay cell and...

article

Wideband LNA using series RLC input matching and resistive feedback

Ji An Park, Choon Sik Cho

Microwave and Optical Technology Letters > 56 > 8 > 1953 - 1956

A low‐noise amplifier (LNA) using series RLC matching network and resistive feedback working from 6.2 to 9.7 GHz is presented. An equivalent circuit model is deduced for obtaining input matching by conversion from parallel circuit to series RLC resonant circuit. Using this equivalent circuit, an LNA is designed without inductive degeneration. By exploiting the resistive feedback and series RLC input...

article

Corrections to “Dielectric Slab Rotman Lens for Microwave/Millimeter-Wave Applications”

Jaeheung Kim, Choon Sik Cho, Frank S. Barnes

IEEE Transactions on Microwave Theory and Techniques > 2014 > 62 > 11 > 2845

chapter

CMOS rectifier for wireless power transmission using multiplier configuration

Nam Hwi Jeong, Yoon Jae Bae, Choon Sik Cho

2013 IEEE MTT-S International Microwave Workshop Series on RF and Wireless Technologies for Biomedical and Healthcare Applications (IMWS-BIO) > 1 - 3

2013 IEEE MTT-S International Microwave Workshop Series on RF and Wireless Technologies for Biomedical and Healthcare Applications (IMWS-BIO)

We present a rectifier for wireless power transmission using multiplier configuration in layout for MOSFETs which works at 13.56 MHz, designed to fit in CMOS process where conventionally used diodes are replaced with the cross-coupled MOSFETs. Full bridge rectifier structure without comparators is employed to reduce current consumption and to be working up to higher frequency. Multiplier configuration...

chapter

Design of rectifier with comparator using unbalanced body biasing for wireless power transfer

Byeong Wan Ha, Choon Sik Cho

2013 International SoC Design Conference (ISOCC) > 356 - 359

2013 International Soc Design Conference (ISOCC)

This paper presents a rectifier with comparator using unbalanced body biasing for wireless power transfer in 0.11μm RF CMOS process. The proposed rectifier is composed of MOSFETs and two comparators. The comparator is used to reduce reverse leakage current occurring when the load DC voltage is higher than input RF voltage. For this purpose, unbalanced body biasing is devised. 0.837V sinusoidal RF...

chapter

Design of VCO using bump structure for high-power harmonics

Yoon Jae Bae, Nam Hwi Jeong, Choon Sik Cho

2013 Asia-Pacific Microwave Conference Proceedings (APMC) > 763 - 765

2013 Asia Pacific Microwave Conference - (APMC 2013)

In this paper, we propose a VCO using the negative resistance property of bump structure. The proposed VCO consists of a bump circuit and an LC resonator for obtaining high powers at the harmonic frequencies. The VCO is designed in 0.13μm RF CMOS process. The VCO works at the center frequency of 3.35GHz with −2.1dBm output power while this circuit consumes 20mW with 1.2 V supply. Due to the negative...

chapter

Target detection for UWB radars using the standard deviation

Moon Kwang Jang, Choon Sik Cho

2013 Asia-Pacific Microwave Conference Proceedings (APMC) > 663 - 665

2013 Asia Pacific Microwave Conference - (APMC 2013)

UWB radars operating at 3.1 GHz–10.6 GHz are used for detecting the targets under clutter environment. Since UWB radars deal with various clutters, it is somewhat difficult to discriminate the target accurately. By reflecting the standard deviation of power spectrum, and the improvement factor using moving speed of the radar and antenna angle, target detection is performed by removing multiple clutters...

chapter

Target detection of marine radars using Matrix Bank filters

Moon Kwang Jang, Choon Sik Cho

2012 Asia Pacific Microwave Conference Proceedings > 1046 - 1048

2012 Asia Pacific Microwave Conference (APMC)

Since marine radars have a lot of sea and rain clutters, it is difficult to discriminate the target from them. The improvement factor and the spectrum spread are applied using the parameters of moving speed of radar antenna, speed, angle, etc. in order to detect targets at sea. Target detection is set by applying the proposed Data Matrix Bank-CFAR (DMB-CFAR). In this paper, we design a signal processing...

chapter

A broadband, millimeter wave, asymmetrical Marchand balun in 180 nm SiGe BiCMOS technology

Duane C. Howard, Choon Sik Cho, John D. Cressler

2012 IEEE Radio Frequency Integrated Circuits Symposium > 425 - 428

2012 IEEE Radio Frequency Integrated Circuits Symposium (RFIC)

A silicon-compatible, broadband, millimeter wave Marchand balun operating at a center frequency of 65 GHz is presented. This balun is asymmetrical and broadside-coupled and exhibits excellent performance over a 30–90 GHz frequency range. The gain imbalance is −1.6 dB at 30 GHz, and +0.6 dB at 90 GHz, with a phase imbalance of ± 5.2 degrees, respectively. The balun exhibits good insertion loss and...

article

Indirect evaluation of radiated emissions from a bent signal line on a printed circuit board with two attached cables

Dong‐Yeon Kim, Jae W. Lee, Choon Sik Cho, Haeng S. Lee, more

Microwave and Optical Technology Letters > 53 > 8 > 1832 - 1837

In this article, the radiated emissions mechanism and the variation of radiated emissions level have been analyzed and investigated, respectively, according to the ratio of the horizontal to vertical traces in a bent signal line when a bent signal line on a printed circuit board (PCB) with two attached cables is used.Though many papers concerning two cables attached to a PCB have appeared, it is seen...

article

Design of SIW Cavity-Backed Circular-Polarized Antennas Using Two Different Feeding Transitions

Dong-Yeon Kim, J W Lee, T K Lee, Choon Sik Cho

IEEE Transactions on Antennas and Propagation > 2011 > 59 > 4 > 1398 - 1403

Two circular-polarized circular patch antennas which have novel feeding structures such as a substrate integrated waveguide (SIW), a cavity-backed resonator and two different feeding transitions, are proposed and experimentally investigated in terms of electrical performances, including reflection coefficients, optimized parameter values, circular polarized antenna gain, axial ratios and radiation...

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IMPEDANCE (9)
CMOS INTEGRATED CIRCUITS (7)
IMPEDANCE MATCHING (7)
ANTENNA RADIATION PATTERNS (6)
UHF POWER AMPLIFIERS (6)
ANTENNA MEASUREMENTS (5)
BANDWIDTH (5)
CMOS (5)
FREQUENCY 2.4 GHZ (5)
HARMONIC ANALYSIS (5)
HARMONICS SUPPRESSION (5)
MICROWAVE OSCILLATORS (5)
RADIO FREQUENCY (5)
RESONANT FREQUENCY (5)
ANTENNAS (4)
DUAL BAND (4)
FINITE DIFFERENCE TIME-DOMAIN ANALYSIS (4)
HARMONIC SUPPRESSION (4)
LENSES (4)
METAMATERIALS (4)
MICROWAVE THEORY AND TECHNIQUES (4)
MIXERS (4)
MONOPOLE ANTENNAS (4)
PHASE NOISE (4)
POWER AMPLIFIERS (4)
POWER DIVIDERS (4)
RESONATORS (4)
TRANSMISSION LINES (4)
WIRELESS COMMUNICATION (4)
COMPOSITE RIGHT/LEFT-HANDED TRANSMISSION LINES (3)
DATA MINING (3)
DUAL-BAND (3)
FDTD ALGORITHM (3)
IEEE (3)
INDUCTORS (3)
LINEARITY (3)
MICROSTRIP (3)
MILLIMETRE WAVE ANTENNAS (3)
MULTIFREQUENCY ANTENNAS (3)
OSCILLATORS (3)
PLANAR INVERTED-F ANTENNA (3)
PLANAR INVERTED-F ANTENNAS (3)
ULTRA WIDEBAND ANTENNAS (3)
VCO (3)
VOLTAGE 1.8 V (3)
ACTIVE INDUCTOR (2)
ANTENNA FEEDS (2)
ARRAYS (2)
ATTACHED CABLES (2)
BAND-PASS FILTERS (2)
CAVITY RESONATORS (2)
CHIREIX OUTPHASING POWER AMPLIFIER (2)
CLASS-E POWER AMPLIFIER (2)
CMOS ANALOGUE INTEGRATED CIRCUITS (2)
CMOS TECHNOLOGY (2)
DELAY CELL (2)
DISTORTION (2)
DUAL-BAND ANTENNA (2)
ELECTROMAGNETIC WAVES (2)
FEEDS (2)
FIDELITY (2)
FREQUENCY 1.95 GHZ (2)
FREQUENCY 60 GHZ (2)
FREQUENCY CONVERSION (2)
GAIN (2)
HIGH RESISTIVITY SILICON WAFER (2)
HORN ANTENNAS (2)
HYBRID POWER COMBINER (2)
IMPEDANCE BANDWIDTH (2)
IMPROVEMENT FACTOR (2)
INDUCTANCE (2)
LAYOUT (2)
LENS ANTENNAS (2)
LINEARITY ENHANCEMENT (2)
LOG PERIODIC ANTENNAS (2)
LOGIC GATES (2)
LOW PHASE NOISE (2)
LOW-POWER ELECTRONICS (2)
MATHEMATICAL MODEL (2)
MICROSTRIP ANTENNA ARRAYS (2)
MICROSTRIP ANTENNAS (2)
MICROWAVE CIRCUITS (2)
MICROWAVE FILTERS (2)
MILLIMETER WAVE COMMUNICATION (2)
MIXERS (CIRCUITS) (2)
MODULATION (2)
MOSFET (2)
NONLINEAR PHASE SLOPE (2)
OOK MODULATION (2)
PARASITIC ELEMENTS (2)
PIFA (2)
POWER COMBINERS (2)
POWER SYSTEM HARMONICS (2)
POWER TRANSMISSION LINES (2)
PRINTED CIRCUITS (2)
PROBABILITY DENSITY FUNCTION (2)
PULSE GENERATOR (2)
RADIAL STUB FEEDING (2)
RADIATION PATTERN (2)
RAIN CLUTTER (2)
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INFONA - science communication portal

Search results for: Choon Sik Cho

PLL-based electrical balance CMOS integrated duplexer with hybrid transformer

Active balun using resistive feedback for low gain imbalance

Zigbee transmitter using a low‐power high‐gain up‐conversion mixer

Multiband multistandard frequency synthesizer for mobile TV tuner with LC‐VCO by digital AAC

Wideband high-isolation SPDT RF switch in 0.18- $$\upmu$$ μ m SiGe BiCMOS technology

A low power RF CMOS direct-conversion transmitter using high conversion gain front end for IEEE 802.15.4 standard

Energy transfer and harvesting for RF-Bio applications — Invited

New Design Formulas for Asymmetric Coupled-Section Marchand Balun

A CMOS UWB OOK pulse generator with multiple pulses per bit

Ultra-wideband on-off keying transmitter with multi-pulses/bit for bio-signal detectors

Wideband LNA using series RLC input matching and resistive feedback

Corrections to “Dielectric Slab Rotman Lens for Microwave/Millimeter-Wave Applications”

CMOS rectifier for wireless power transmission using multiplier configuration

Design of rectifier with comparator using unbalanced body biasing for wireless power transfer

Design of VCO using bump structure for high-power harmonics

Target detection for UWB radars using the standard deviation

Target detection of marine radars using Matrix Bank filters

A broadband, millimeter wave, asymmetrical Marchand balun in 180 nm SiGe BiCMOS technology

Indirect evaluation of radiated emissions from a bent signal line on a printed circuit board with two attached cables

Design of SIW Cavity-Backed Circular-Polarized Antennas Using Two Different Feeding Transitions

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