Jeongseon Lee

Korea Advanced Institute of Science and Technology, Sŏul, Seoul, South Korea

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Publications (8)8.04 Total impact

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    ABSTRACT: This paper presents a high-linearity low-noise small-size programmable gain amplifier (PGA) based on a new low-noise low-distortion transconductor and a proposed reconfiguration technique. The proposed transconductor combines an inverter-based differential pair with an adaptive biasing circuit to reduce noise and distortion. The reconfiguration technique saves the chip size by half and improves the bandwidth of the amplifier by utilizing the same differential pair for the input transconductance and load-stage, interchangeably. Fabricated in 0.18-μm CMOS, the proposed PGA shows a dB-linear control range of 21dB in 16 steps from -11dB to 10dB with a gain error of less than ±0.33dB, an IIP3 of 7.4÷14.5dBm, a P1dB of -7÷1.2dBm, a noise figure of 13dB, and a 3-dB bandwidth of 270MHz at the maximum gain, respectively. The PGA occupies a chip area of 0.04 mm2 and consumes only 1.3mA from the 1.8V supply.
    ESSCIRC, 2010 Proceedings of the; 10/2010
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    ABSTRACT: This paper describes a wide-band sharp-rejection active-RC low pass filter (LPF) for pulse-based UWB IEEE 802.15.4a WPAN applications. Sharp rejection is attributed to the combination of different AC characteristic of three biquads in series. A simple operational amplifier (Op-amp) is adopted to ensure high frequency performance for the designed filter. The LPF is designed in 0.13 mum TSMC CMOS process. The cutoff frequency is 380 MHz with about 50% of the tuning range from 300-500 MHz. The rejection is 40 dB at 600 MHz. The passband ripple is less than 1.5 dB and the filter consumes 4.6 mA from 1.2 V supply. Core chip size is 580 times 700 mum<sup>2</sup>.
    Circuits and Systems, 2009. ISCAS 2009. IEEE International Symposium on; 06/2009
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    ABSTRACT: This paper presents an energy-efficient low-complexity pulse-generator design technique for multiband impulse-radio ultrawide-band (IR-UWB) system in 0.18-mum CMOS technology. The short pulses are generated based on the on/off switching operation of an oscillator with subband switching functionality, which is mandatory for multiband IR-UWB systems. The relation between the oscillator switching operation and the resulting output pulse envelope, which determines pulse spectral characteristics, is analyzed, and the design guidelines for topology and component values are presented. Measurements show the output pulses with the duration of 3.5 ns, which corresponds to 520-MHz bandwidth. The output pulse spectrum centered at 3.8 GHz fully complies with the Federal Communication Commission spectral mask with more than 25 dB of sidelobe suppression without the need for additional filtering. Thus, the low-complexity pulse generator can maintain its simplicity for low cost with core chip size of 0.3 mm<sup>2</sup>. The pulse generator shows an excellent energy efficiency with average energy dissipation of 16.8 pJ per pulse from 1.5-V supply. The proposed pulse generator is best suited for energy-detection IR-UWB systems.
    Circuits and Systems I: Regular Papers, IEEE Transactions on 01/2009; · 2.24 Impact Factor
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    ABSTRACT: A fully integrated RF front-end receiver for 3-5 GHz UWB application is reported. Low noise amplifier (LNA) adopts wide simultaneous noise and input matching technique to get better noise performance. Folded double balanced down conversion mixer is integrated with LNA implemented by 0.13 mum CMOS technology. Measured noise figure (NF) of each band (3432, 3960, and 4488 MHz) is 2.5, 3.3, and 4.2 dB at 100 MHz IF, respectively. Voltage conversion gain is measured as 19.4 dB to 23.5 dB. At the maximum gain band, -20 dBm IIP3 and -28 dBm PldB are measured. The total current is 14 mA from a 1.5 V supply.
    Advanced Communication Technology, 2008. ICACT 2008. 10th International Conference on; 03/2008
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    ABSTRACT: A two-stage, common-gate in cascade with cascode, ultra wideband low noise amplifier (LNA) topology is proposed for 3.1 to 10.5 GHz full band application. The common-gate first stage is adopted and optimized for low noise figure (NF) at high frequencies. The LNA implemented in 0.18 mum CMOS shows more than 10 dB input return loss, maximum gain of 16 dB, and NF of 3.8~4.0 dB over the full frequency band while dissipating 5.3 mA from 1.8 V supply.
    IEEE Microwave and Wireless Components Letters 11/2007; · 1.78 Impact Factor
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    ABSTRACT: This letter presents a new transmitter for multiband impulse radio ultra-wideband (IR-UWB) systems. The ultra low-power, low-complexity UWB transmitter operates over three 528-MHz subbands in 3-5 GHz band. It consists of an on-off keying (OOK) modulator and a pulse generator which is based on the ON/OFF switching operation of an LC oscillator. Measurements show a pulse duration of 3.5 ns and a spectrum that fully complies with the FCC spectral mask with more than 20 dB of sidelobe rejection. Implemented in 0.18-mum CMOS technology, the transmitter operates in burst mode and dissipates only 18 pJ of energy consumption per pulse. The transmitter is best suited for energy detection receivers.
    IEEE Microwave and Wireless Components Letters 10/2007; · 1.78 Impact Factor
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    ABSTRACT: This paper presents a low-power RF receiver/transmitter front-end for 2.4-GHz-band IEEE 802.15.4 standard in 0.18-mum CMOS technology. An RF receiver comprises a single-ended low-noise amplifier, a quadrature passive mixer, and a transimpedance amplifier. A current-mode passive mixer showing a very good 1/f noise performance is adopted to convert an RF signal directly to a baseband signal. Moreover, this type of passive mixer shows high-linearity performance, leading to overall RF receiver linearity improvement. A low-power, high-linearity transmitter front-end is implemented by using a passive mixer and two-stage driver amplifier in which the first stage is a conventional cascode amplifier and the second stage uses a folded cascode one. The receiver front-end achieves 30-dB voltage conversion gain, 7.3-dB noise figure with 1/f noise corner frequency of 70 kHz, -8-dBm input third-order intercept point, and +40-dBm input second-order intercept point. The transmitter front-end shows 12-dB power conversion gain, 0-dBm output power with 10-dBm output third-order intercept point, and -30-dB local-oscillator suppression. The receiver and transmitter front-end dissipate 3.5 and 3 mA from a 1.8-V supply, respectively
    IEEE Transactions on Microwave Theory and Techniques 01/2007; · 2.23 Impact Factor
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    ABSTRACT: This paper describes a wideband sharprejection activeRC low pass filter (LPF) for pulsebased UWB IEEE 802.15.4a WPA, applications. Sharp rejection is attributed to the combination of different AC characteristic of three biquads in series. A simple operational amplifier (Opamp) is adopted to ensure high frequency performance for the designed filter. The LPF is designed in 0.13µm TSMC CMOS process. The cutoff frequency is 380MHz with about 50% of the tuning range from 300�500MHz. The rejection is 40 dB at 60 0 MHz. The passband ripple is less than 1.5dB and the filter consumes 4.6mA from 1.2V supply. Core chip size is 580 x 700µm 2.