CONTACT

[Tel] +82-42-350-7558
[Address]

Bldg. E3-2, Rm. 5214,

291, Daehak-ro, Yuseong-gu, Daejeon

34141, Republic of Korea

  2020

Y. Lee=, T. Seong=, J. Lee, C. Hwang, H. Park, and J. Choi*, "A -240dB-FOMJIT and -115dBc/Hz-100kHz-PN, 7.7GHz-Ring-DCO-Based Digital PLL Using P/I-Gain Co-Optimization and Sequence-Rearranged Optimally Spaced TDC for Flicker-Noise Reduction," IEEE International Solid-State Circuits Conference (ISSCC), accepted for presentation, Feb. 2020. (= Equally-Credited Authors)

T. Seong=, Y. Lee=, C. Hwang, J. Lee, H. Park, K. Lee, and J. Choi*, "A -58dBc-Worst Fractional Spur and -234dB-FOMJIT, 5.5GHz-Ring-DCO-Based Fractional-N DPLL Using a Time-Invariant-Probability Modulator, Generating a Nonlinearity-Robust DTC-Control Word," IEEE International Solid-State Circuits Conference (ISSCC), accepted for presentation, Feb. 2020. (= Equally-Credited Authors)

Y. Lim=, J. Kim=, Y. Jo, J. Bang, S. Yoo, H. Park, H. Yoon, and J. Choi*, "A 170MHz-Lock-In-Range and -253dB-FOMJIT, 12-14.5GHz Subsampling PLL with 150μW Frequency-Disturbance-Correcting Loop Using a Low-Power Unevenly Spaced Edge Generator," IEEE International Solid-State Circuits Conference (ISSCC), accepted for presentation, Feb. 2020. (= Equally-Credited Authors)

  2019

J. Lee, J. Bang, Y. Lim, S. Yoo, Y. Lee, T. Seong, and J. Choi*, "A Fast-Transient and High-Accuracy, Adaptive-Sampling Digital LDO Using a Single VCO-Based Edge-Racing Time Quantizer," IEEE Solid-State Circuits Letters (SSC-L), Oct. 2019, invited from IEEE 2019 Symp. VLSI Circuits.

J. Kim, Y. Lim, H. Yoon, Y. Lee, H. Park, Y. Cho, T. Seong, and J. Choi*, "An Ultra-Low-Jitter, mmW-Band Frequency Synthesizer Based on Digital Subsampling PLL Using Optimally-Spaced Voltage Comparators," IEEE Journal of Solid-State Circuits, Dec. 2019, invited from IEEE 2019 International Solid-State Circuits Conference (ISSCC).

S. Park, J. Kim, C. Hwang, H. Park, S. Yoo, T. Seong, and J. Choi*, "A 0.1-1.5 GHz Wide Harmonic-Locking-Free Delay-Locked Loop Using an Exponential DAC", IEEE Microwave and Wireless Components LettersAug. 2019.

T. Seong, Y. Lee, S. Yoo, and J. Choi*, "A 320-fs RMS-Jitter and −75-dBc Reference-Spur Ring-DCO-Based Digital PLL Using an Optimal-Threshold TDC," IEEE Journal of Solid-State Circuits, Jun. 2019.

J. Lee, J. Bang, Y. Lim, and J. Choi*, "A 0.5V-VIN, 0.29ps-Transient-FOM, and Sub-2mV-Accuracy Adaptive-Sampling Digital LDO Using Single-VCO-Based Edge-Racing Time Quantizer," IEEE Symp. VLSI Circuits Dig., Jun. 2019.

H. Yoon, S. Park, and J. Choi*, "A Low-Jitter Injection-Locked Multi-Frequency Generator using Digitally-Controlled Oscillators and Time-Interleaved Calibration," IEEE Journal of Solid-State Circuits, Feb. 2019.

S. Choi, S. Yoo, Y. Lee, Y. Jo, J. Lee, Y. Lim, and J. Choi*, "An Ultra-Low-Jitter 22.8-GHz Ring-LC-Hybrid Injection-Locked Clock Multiplier with a Multiplication Factor of 114," IEEE Journal of Solid-State Circuits, Apr. 2019, invited from IEEE 2018 Symp. VLSI Circuits.

J. Kim=, H. Yoon=, Y. Lim=, Y. Lee, Y. Cho, T. Seong, and J. Choi*, "A 76fsRMS-Jitter and 40dBc-Integrated-Phase-Noise 2831GHz Frequency Synthesizer Based on Digital Sub-Sampling PLL Using Optimally Spaced Voltage Comparators and Background Loop-Gain Optimization," IEEE International Solid-State Circuits Conference (ISSCC), Feb. 2019. (= Equally-Credited Authors)

S. Yoo, S. Choi, Y. Lee, T. Seong, Y. Lim and J. Choi*, "A 140fsRMS-Jitter and −72dBc-Reference-Spur Ring-VCO-Based Injection-Locked Clock Multiplier Using a Background Triple-Point Frequency/Phase/Slope Calibrator," IEEE International Solid-State Circuits Conference (ISSCC), Feb. 2019.

  2018

Y. Lim, J. Lee, S. Park, Y. Jo, and J. Choi*, "An External Capacitorless Low-Dropout Regulator with High PSR at All Frequencies from 10 kHz to 1 GHz Using an Adaptive Supply-Ripple Cancellation Technique," IEEE Journal of Solid-State Circuits, Sep. 2018.

Y. Lim, J. Lee, Y. Lee, S. Yoo, and J. Choi*, "A 320uV-Output Ripple and 90ns-Settling Time at 0.5V Supply Digital-Analog-Hybrid LDO Using Multi-Level Gate-Voltage Generator and Fast-Decision PD Detector," IEEE European Solid-State Circuits Conference (ESSCIRC), Sep. 2018.

K. Lim*, S. Lee, Y. Lee, Y. Lim, C. Song, J. Seong, J. Choi, and S. Han, "A 65nm CMOS 2×2 MIMO Multi-band LTE RF Transceiver for Small Cell Base Stations," IEEE Journal of Solid-State Circuits, Jul. 2018.

S. Choi, S. Yoo, Y. Lee, Y. Jo, J. Lee, Y. Lim, and J. Choi*, "153 fs RMS-Integrated-Jitter and 114-Multiplication Factor PVT-Robust 22.8 GHz Ring-LC-Hybrid Injection-Locked Clock Multiplier," IEEE Symp. VLSI Circuits Dig., Jun. 2018.

Y. Lee, T. Seong, S. Yoo, and J. Choi*, "A Low-Jitter and Low-Reference-Spur Ring-VCO-Based Switched-Loop-Filter PLL Using a Fast Phase-Error Correction Technique," IEEE Journal of Solid-State Circuits, Apr. 2018.

J. Lee, S. Choi, Y. Cho, and J. Choi*, "A linearly frequency-tunable and low-phase noise ring VCO using varactors with optimally-spaced bias voltages," Electronics Letters, Mar. 2018.

H. Yoon, J. Kim, S. Park, Y. Lim, Y. Lee, J. Bang, K. Lim, and J. Choi*, "A -31dBc Integrated-Phase-Noise 29GHz Fractional-N Frequency Synthesizer Supporting Multiple Frequency Bands for Backward-Compatible 5G Using a Frequency Doubler and Injection-Locked Frequency Multipliers," IEEE International Solid-State Circuits Conference (ISSCC), Feb. 2018.

T. Seong, Y. Lee, S. Yoo, and J. Choi*, "A -242dB FOM and -75dBc-Reference-Spur Ring-DCO based All-Digital PLL Using a Fast Phase-Error Correction Technique and a Low-Power Optimal-Threshold TDC," IEEE International Solid-State Circuits Conference (ISSCC), Feb. 2018.

S. Yoo, S. Choi, J. Kim, H. Yoon, Y. Lee, and J. Choi*, "A Low-Integrated-Phase-Noise 27-30-GHz Injection-Locked Frequency Multiplier with an Ultra-Low-Power Frequency-Tracking Loop for mm-Wave-Band 5G Transceivers," IEEE Journal of Solid-State Circuits, Feb. 2018. 

  2017

Y. Lim, J. Lee, Y. Lee, S. Song, H. Kim, O. Lee, and J. Choi*, "An External Capacitor-Less Ultra-Low Dropout Regulator Using a Loop-Gain Stabilizing Technique for High Power Supply Rejection over a Wide Range of Load Current," IEEE Transactions on Very Large Scale Integration (VLSI) Systems, Nov. 2017.

S. Park, H. Yoon, and J. Choi*, "An Ultra-Low Phase Noise All-Digital Multi-Frequency Generator Using Injection-Locked DCOs and Time-Interleaved Calibration," IEEE Asian Solid-State Circuits Conference (ASSCC), Nov. 2017.

H. Ahn, S. Baek, I. Nam, D. Ahn, J. Lee, J. Choi, and O. Lee*, "A fully integrated dual-mode CMOS power amplifier with an autotransformer-based parallel combining transformer," IEEE Microwave and Wireless Components Letters, Aug. 2017.

D. Shin, T. Seong, J. Choi*, W. Choi*, "Self-sustaining water-motion sensor platform for continuous monitoring of frequency and amplitude dynamics," Elsevier Nano Energy, May 2017. 

T. Seong, Y. Lee, S. Yoo, and J. Choi*, "A –242-dB FOM and –71-dBc Reference Spur Ring-VCO-based Ultra-Low-Jitter PLL," IEEE Symp. VLSI Circuits Dig., Jun. 2017.

Y. Lim, J. Lee, S. Park, and J. Choi*, "An External-Capacitor-less Low-Dropout Regulator with Less than –36dB PSRR at All Frequencies from 10kHz to 1GHz Using an Adaptive Supply-Ripple Cancellation Technique to the Body-Gate," IEEE Custom Integrated Circuits Conference (CICC), May 2017.

S. Yoo, S. Choi, J. Kim, H. Yoon, Y. Lee, and J. Choi*, "A PVT-Robust 29GHz Injection-Locked Frequency Multiplier with a 600uW Frequency-Tracking Loop for mm-Band 5G Transceivers," IEEE International Solid-State Circuits Conference(ISSCC), Feb. 2017.

  2016

S. Kim, K. Kim, Y. Hwang, J. Park, Y. Kang, M. Kim, Z. Lee, J. Choi, Y. Kim, S. Jeong, B. Bae, J. Park*, "High-resolution electrohydrodynamic inkjet printing of stretchable metal oxide semiconductor transistors with high performance," Nanoscale, Sep. 2016.

S. Choi, S. Yoo, Y. Lim, and J. Choi*, "A PVT-Robust and Low-Jitter Ring-VCO-Based Injection-Locked Clock Multiplier with a Continuous Frequency-Tracking Loop Using a Replica-Delay Cell and a Dual-Edge Phase Detector," IEEE Journal of Solid-State Circuits, Aug. 2016.

Y. Lee, H. Yoon, M. Kim, and J. Choi*, "A PVT-robust −59-dBc reference spur and 450-fsRMS jitter injection-locked clock multiplier using a voltage-domain period-calibrating loop," IEEE Symp. VLSI Circuits Dig., Jun. 2016.

H. Yoon, Y. Lee, Y. Lim, G. Tak, H. Kim, Y. Ho, and J. Choi*, "A 0.56 – 2.92 GHz Wideband and Low Phase Noise Quadrature LO-Generator Using a Single LC-VCO for 2 – 4G Multi-Standard Cellular Transceivers," IEEE Journal of Solid-State Circuits, Mar. 2016.

M. Kim, S. Choi, T. Seong, and J. Choi*, "A Low-Jitter and Fractional-Resolution Injection-Locked Clock Multiplier Using a DLL-Based Real-time PVT-Calibrator with Replica-Delay Cells," IEEE Journal of Solid-State Circuits, Feb. 2016.

S. Yoo, S. Choi, T. Seong, and J. Choi*, "An Ultra-Low Power and Compact LC-Tank-Based Frequency Tripler Using Pulsed Input Signals," IEEE Microwave and Wireless Components Letters, Feb. 2016.

S. Choi, S. Yoo, and J. Choi*, "A 185-fsrms Integrated-Jitter and –245-dB FOM PVT-Robust Ring-VCO-Based Injection-Locked Clock Multiplier with a Continuous Frequency-Tracking Loop Using a Replica-Delay Cell and a Dual-Edge Phase Detector," IEEE International Solid-State Circuits Conference (ISSCC), Feb. 2016, Silkroad Award awarded. 

  2015

 

Y. Kang, J. Choi*, and Y. Kim*, "A Wide Range On-Chip Leakage Sensor Using a Current-Frequency Converting Technique in 65-nm Technology Node," IEEE Transactions on Circuits and Systems II, Sep. 2015.

 

M. Kim, S. Choi, and J. Choi*, "A 450-fs Jitter PVT robust fractional-resolution injection-locked clock multiplier using a DLL-based calibrator with replica-delay-cells," in IEEE Symp. VLSI Circuits Dig., Jun. 2015.

 

Y. Lee, M. Kim, T. Seong, and J. Choi*, "A Low Phase Noise Injection-Locked Programmable Reference Clock Multiplier with a Two-Phase PVT-Calibrator for ΔΣ PLLs," IEEE Transactions on Circuits and Systems I, Mar. 2015.

 

T. Seong, and J. Choi*, "Analysis and Design of a Core-Size-Scalable Low Phase Noise LC-VCO for Multi-Standard Cellular Transceivers ,"  IEEE Transactions on Circuits and Systems I, Mar. 2015.

 

  2014

 

D. Kim, S. Choi, J. Choi, and J. Kim*, "A Reconfigurable Multi-Phase LC-Ring Structure for Programmable Frequency Multiplication," IEEE Transactions on Circuits and Systems II, Oct. 2014.


S. Kim, W. Eom, J. Choi, and J. Kim*, "Dual-mode wide-range linear CMOS interface circuit for resistive sensors," IET Electronics Letters, Oct. 2014.

Y. Tang*, J. Choi, J. Park, L. Leung, and C. Narathong, "Varactorless tunable oscillator-patent abstracts," IEEE Journal of Solid-State Circuits, Oct. 2014.


T. Seong, Y. Lee, and J. Choi*, "An Ultra-Low In-Band Phase Noise Injection-Locked Frequency Multiplier Design Based on Open-Loop Frequency Calibration," IEEE Transactions on Circuits and Systems II, Sep. 2014.

H. Yoon, Y. Lee, and J. Choi*, "A Wideband Dual-Mode LC-VCO With a Switchable Gate-Biased Active Core," IEEE Transactions on Circuits and Systems II, Mar. 2014. 

  2013

S. Yoo, J. Kim, and J. Choi*, "A 2-8 GHz Wideband Dually Frequency-Tuned Ring-VCO with a Scalable Kvco", IEEE Microwave and Wireless Components Letters, Sep. 2013.

 

Y. Tang*, J. Hu, J. Park, J. Choi*, et al., "A CMOS Highly Linear Hybrid Current/Voltage Controlled Oscillator for Wideband Polar Modulation," IEEE Transactions on Circuits and Systems I, Aug. 2013.

  2012

 

J. Choiet al., "A high-resolution offset-frequency PLL using properties of co-prime numbers", IET Electronics Letters, Nov. 2012.

 

Y. Tang*, J. Hu, J. Park, J. Choi, L. Leung, C. Narathong, and K. Sahoto, "A 65nm CMOS current controlled oscillator with high tuning linearity for wideband polar modulation," Custom Integrated Circuits Conference, 2012 IEEE , vol., no., pp.1-4, 9-12 Sept. 2012.

 

J. Choiet al., “A Spur Suppression Technique using an Edge-Interpolator for a Charge-Pump PLL,” IEEE Transactions on Very Large Scale Integration (VLSI) Systems, May 2012.

  2011

S. Kim, J. Choi, K. Chae, S. Beck, S. Kim, F. Bien, C. Lee, K. Lim, J. Laskar, and M. Tentzeris, “A Non-Interruptive Link-Variation Monitoring Circuit for Wireless Sensor Applications,” IEEE Microwave and Wireless Components Letters, Nov. 2011.

J. Choi, S. Kim, et al., “A Low Power and Wide Range Programmable Clock Generator with a High Multiplication Factor,” IEEE Transactions on Very Large Scale Integration (VLSI) Systems, Apr. 2011.

 

J. Kim, K. Lee, J. Choi, et al., "Ultra-wideband CMOS voltage-controlled oscillator with reconfigurable tunarable inductors," IET Electronics Letters, vol. 47, no.4. pp.249-250, Feb. 2011.

  2010

 

J. Kim, J. Choi, et al., "Wideband CMOS voltage-controlled oscillator using tunable inductors," IET Electronics Letters, vol.46, no.20, pp.1391-1393, Sep. 2010.

 

S. Kim, T. Song, J. Choi, et al.,“ Semi-Active High-Efficient CMOS Rectifier for Wireless Power Transmission,” IEEE RFIC Symposium, May 2010.

 

S. Kim, J. Choi, et al., “Subthreshold Current Mode Matrix Determinant Computation for Analog Signal Processing,” IEEE ISCAS, Jun. 2010.

 

T. Song, J. Park, J. Choi, et al., "A 122-mW Low-Power Multiresolution Spectrum-Sensing IC With Self-Deactivated Partial Swing Techniques," IEEE Transactions on Circuits and Systems II, vol.57, no.3, pp.188-192, Mar. 2010.

  2009

 

J. Choi, J. Park, et al., “High Multiplication Factor Capacitor Multiplier for an On-chip PLL Loop Filter,” IET Electronics Letters, Feb. 2009.

 

J. Choi, et al., "A ring VCO with wide and linear tuning characteristics for a cognitive radio system," IEEE RFIC Symposium, pp.395-398, June 2008, nominated for the best student paper award.

 

  U.S. Patents

 

J. Choi, Y. Tang, “Configurable multi-mode oscillators”, WO2014008141 A1, Jan. 2014, published.

 

Y. Tang, J. Choi, C. Narathong, “Varactorless tunable oscillator”, WO2012112587 A1, Aug. 2012, published.

Publications