Soon-Jae Kweon

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A charge sampler-based reconfigurable high-order moving-average (MA) filter designed using a temporal MA method is proposed. The proposed filter has a higher gain than conventional MA filters. Moreover, the filter supports variable sizes and orders of MA. That is, the filter has a flexible frequency response by changing not only the sampling frequency but(More)
This paper proposes a low-power polar demodulator for electrical impedance spectroscopy. The magnitude and phase of impedance are measured by a novel sampling scheme and an XOR-based scheme, respectively. The novel sampling scheme only requires switched capacitor circuits and clock signals that are already used in the analog-to-digital conversion and the(More)
This paper proposes an interface IC for a breath analyzer with four three-electrode metal-oxide gas sensors and a humidity sensor. The mode-changeable integrator is a common circuit for both the resistive sensing and the capacitive sensing. The proposed interface circuit covers a wide range of the resistance from 100 ohms to 2 Mohms and a capacitance range(More)
A hybrid baseband chain for Long-Term Evolution (LTE) was implemented in a TSMC 65-nm CMOS process. It has an active area of 0.75 mm<sup>2</sup> and a power consumption of 10.8 mW at a supply of 1.8 V. The proposed baseband chain consists of a continuous-time (CT) lowpass filter and a charge-domain discrete-time (DT) filter with a variable gain amplifier(More)
A CMOS sinusoidal signal generator based on discrete-time (DT) and continuous-time (CT) processing is proposed for electrical bioimpedance spectroscopy supporting beta dispersion range of tissues. Differential stepwise sine-like signals with oversampling ratio (OSR) of 16 are used for input signals. DT filters with OSR&#x003D;16 are used to attenuate(More)
We propose a time-to-digital converter (TDC) with a reconfigurable time resolution from 0.1 ns to 244 ns using a low-speed reference clock of 32.768 MHz. This TDC combines a coarse counter with two parallel fine TDCs which measure front and back fractional times of the coarse counter. In order to obtain high precision without increasing the reference clock(More)
A CMOS integrated low-power polar demodulator for electrical bioimpedance spectroscopy is proposed. This polar demodulator extracts magnitude and phase of tissue's impedance. Two adaptive self-sampling schemes, namely zero-time sampling (ZTS) and peak-time sampling (PTS), are proposed to efficiently extract the magnitude of impedance. Since ZTS scheme(More)
This paper proposes a novel architecture of time-to-digital converter (TDC) with wide input range in polar demodulators for electrical impedance spectroscopy (EIS) systems. The system combines a counter-based TDC with cascaded time interpolation stages and efficiently quantizes the phase component. The maximum phase error of 0.52 degrees from 1-kHz to(More)
A non-decimation second-order spatial moving average (SMA) discrete-time (DT) filter is proposed with reconfigurable null frequencies. The filter coefficients are changeable, and it can be controlled by switching sampling capacitors. So, interferers can be rejected effectively by flexible nulls. Since it operates without decimation, it does not change the(More)
A discrete-time channel-selection filter with flat passband characteristic that satisfies the LTE specification is proposed. To improve the flatness in passband, a second order IIR filter and a compensation filter are adopted. High stopband attenuation is achieved by using the moving average filters. Through the control of sampling frequency, the proposed(More)
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