• Journal of Korea Multimedia Society
• /
• v.6 no.2
• /
• pp.319-324
• /
• 2003

In this paper, a new wideband tunable analog element for multimedia system is proposed. The proposed active element is composed of the complementary cascode circuit which can extend transconductance of an element. Therefore, the unity gain frequency which is determined transconductance is increased than that of the conventional element. And then these results are verified by the 0.22$\mu\textrm{m}$ CMOS n-well parameter simulation. As a result, the gam and the unity gam frequency are 42dB and 200MHz on 2V supply voltage. And power dissipation of the designed element is 0.32mW.

• Journal of Biomedical Engineering Research
• /
• v.24 no.1
• /
• pp.1-8
• /
• 2003

The job of long distance driving is likely to be fatiguing and requires long period alertness and attention, which make considerable demands of the driver. Driving fatigue contributes to driver related with accidents and fatalities. In this study, we investigated the relationship between the number of hours of driving and driving fatigue using heart rate variability(HRV) signal. With a more traditional measure of overall variability (standard deviation, mean, spectral values of heart rate). Nonlinear characteristics of HRV signal were analyzed using Approximate Entropy (ApEn) and Poincare plot. Five subjects drive the four passenger vehicle twice. All experiment number was 40. The test route was about 300Km continuous long highway circuit and driving time was about 3 hours. During the driving, measures of electrocardiogram(ECG) were performed at intervals of 30min. HRV signal, derived from the ECG, was analyzed using time, frequency domain parameters and nonlinear characteristic. The significance of differences on the response to driving fatigue was determined by Student's t-test. Differences were considered significant when a p value < 0.05 was observed. In the results, mean heart rate(HRmean) decreased consistently with driving time, standard deviation of RR intervals(SDRR), standard deviation of the successive difference of the RR intervals(SDSD) increased until 90min. Hereafter, they were almost unchanging until the end of the test. Normalized low frequency component $(LF_{norm})$, ratio of low to high frequency component (LF/HF) increased. We used the Approximate Entropy(ApEn), Poincare plot method to describe the nonlinear characteristics of HRV signal. Nonlinear characteristics of HRV signals decreased with driving time. Statistical significant is appeared after 60 min in all parameters.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.42 no.6
• /
• pp.67-76
• /
• 2005

This paper proposes a compact-sized surface myoelectric sensor for the myoelectric hand prosthesis. To fit the surface myoelectric sensor in the socket for the myoelectric hand prosthesis, the sensor should be a compact size. The surface myoelectric sensor is. composed of a skin interface and a single processing circuit that are mounted on a single package. The skin interface has one reference and two input electrodes, and the reference electrode is located in the center of two input electrodes. In this paper we propose two types of sensors with the circle- and bar-shaped reference electrode, but all input electrodes are the bar-shaped. The metal material of the electrodes is the stainless steel (SUS440) that endures sweat and wet conditions. Considering the conduction velocity and the median frequency of the myoelectric signal, we select the inter-electrode distance (IED) between two input electrodes as 18mm, 20mm, and 22 mm. The signal processing circuit consists of a differential amplifier with a band pass filter, a band rejection filter for rejecting 60Hz power-line noise, amplifiers, and a mean absolute value circuit. We evaluate the proposed sensor from the output characteristics according to the IED and the shape of the reference electrode. From the experimental results we show the surface myoelectric sensor with the 18mm IED and the bar-shaped reference electrode is suitable for the myoelectric hand prosthesis.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.48 no.12
• /
• pp.91-96
• /
• 2011

In this paper, a low-power direct-conversion transmitter based on current-mode operation, which satisfies the IEEE 802.15.4 standard, is proposed and implemented in a $0.13{\mu}m$ CMOS technology. The proposed transmitter consists of DACs, LPFs, variable gain I/Q up-conversion mixer, a divide-by-two circuit with LO buffer, and a drive amplifier. By combining DAC, LPF, and variable gain I/Q up-conversion mixer with a simple current mirror configuration, the transmitter's power consumption is reduced and its linearity is improved. The drive amplifier is a cascode amplifier with gain controls and the 2.4GHz I/Q differential LO signals are generated by a divide-by-two current-mode-logic (CML) circuit with an external 4.8GHz input signal. The implemented transmitter has 30dB of gain control range, 0dBm of maximum transmit output power, 33dBc of local oscillator leakage, and 40dBc of the transmit third harmonic component. The transmitter dissipates 10.2mW from a 1.2V supply and the die area of the transmitter is $1.76mm{\times}1.26mm$.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2011.10a
• /
• pp.423-424
• /
• 2011

This paper has proposed a 920 MHz RF front-end for IEEE 802.15.4g SUN (Smart Utility Network) systems. The proposed 920 MHz RF front-end consists of a driver amplifier, a low noise amplifier, and a RF switch. In the TX mode, the driver amplifier has been designed as a single-ended topology to remove a transformer which causes a loss of the output power from the driver amplifier. In addition, a RF switch is located in the RX path not the TX path. In the RX mode, the proposed low noise amplifier can provide a differential output signal when a single-ended input signal has been applied to. A LC resonant circuit is used as both a load of the drive amplifier and a input matching circuit of the low noise amplifier, reducing the chip area. The proposed 920 MHz RF Front-end has been implemented in a 0.18-um CMOS technology. It consumes 3.6 mA in driver amplifier and 3.1 mA in low noise amplifier from a 1.8 V supply voltage.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.40 no.9
• /
• pp.673-684
• /
• 2003

A degenerated differential pair has been widely used as a standard topology for digitally programmable CMOS VGAs. A variable degeneration resistor has been implemented using a resistor string or R-2R ladder with MOSFET switches. However, in the VGAs using these conventional methods, low-voltage and high-speed operation is very hard to achieve due to the dc voltage drop over the degeneration resistor. To overcome this problem a new variable degeneration resistor is proposed where the dc voltage drop is almost removed. Using the proposed gain control scheme, a low-voltage and high-speed CMOS VGA is designed. HSPICE simulation results using a 0.25${\mu}{\textrm}{m}$ CMOS process parameters show that the designed VGA provides a 3dB bandwidth of 360MHz and a 80dB gain control range in 2dB step. Gain errors are less than 0.4dB at 200MHz and less than l.4dB at 300MHz. The designed circuit consumes 10.8mA from a 2.5V supply and its die area is 1190${\mu}{\textrm}{m}$${\times}$360${\mu}{\textrm}{m}$.

• Journal of the Institute of Electronics Engineers of Korea SC
• /
• v.44 no.1
• /
• pp.85-93
• /
• 2007

This paper presents new LVDS I/O circuits with a high noise margin for use in highly parallel I/O environments. The proposed LVDS I/O includes transmitter and receiver parts. The transmitter circuits consist of a differential phase splitter and a output stage with common mode feedback(CMFB). The differential phase splitter generates a pair of differential signals which have a balanced duty cycle and $180^{\circ}$ phase difference over a wide supply voltage variation due to SSO(simultaneous switching output) noises. The CMFB output stage produces the required constant output current and maintains the required VCM(common mode voltage) within ${\pm}$0.1V tolerance without external circuits in a SSO environment. The proposed receiver circuits in this paper utilizes a three-stage structure(single-ended differential amp., common source amp., output stage) to accurately receive high-speed signals. The receiver part employs a very wide common mode input range differential amplifier(VCDA). As a result, the receiver improves the immunities for the common mode noise and for the supply voltage difference, represented by Vgdp, between the transmitter and receiver sides. Also, the receiver produces a rail-to-rail, full swing output voltage with a balanced duty cycle(50% ${\pm}$ 3%) without external circuits in a SSO environment, which enables correct data recovery. The proposed LVDS I/O circuits have been designed and simulated with 0.18um TSMC library using H-SPICE.

• Journal of IKEEE
• /
• v.7 no.1 s.12
• /
• pp.43-55
• /
• 2003

A degenerated differential pair has been widely used as a standard topology for digitally programmable CMOS VGAs. A variable degeneration resistor has been implemented using a resistor string or R-2R ladder with MOSFET switches. However, in the VGAs using these conventional methods, low-voltage and high-speed operation is very hard to achieve due to the dc voltage drop over the degeneration resistor. To overcome the problem a new variable degeneration resistor is proposed where the dc voltage drop is almost removed. The proposed gain control scheme makes it easy to implement a low-voltage and high-speed VGA. This paper describes the problems existed in conventional methods, the principle and advantages of the proposed scheme, and their performance comparison in detail. A CMOS VGA cell is designed using the proposed degeneration resistor. The 3dB bandwidths are greater than 650㎒ and the gain errors are less than 0.3dB in a gain control range from -12dB to +12dB in 6dB steps. It consumes 3.1㎃ from a 2.5V supply voltage.

• Journal of the Institute of Electronics and Information Engineers
• /
• v.51 no.12
• /
• pp.90-95
• /
• 2014

This paper presents a VHF/UHF-band variable gain low noise amplifier for multi-standard mobile TV tuners. A proposed VHF-band variable gain amplifier is composed of a resistive shunt-feedback low noise amplifier to remove external matching components, a single-to-differential amplifier with input PMOS transcoductors to improve low frequency noise performance, a variable shunt-feedback resistor and an attenuator to control variable gain range. A proposed UHF-band variable gain amplifier consists of a narrowband low noise amplifier with capacitive tuning to improve noise performance and interference rejection performance, a single-to-differential with gm gain control and an attenuator to adjust gain control range. The proposed VHF-band and UHF-band variable gain amplifier were designed in a $0.18{\mu}m$ RF CMOS technology and draws 22 mA and 17 mA from a 1.8 V supply voltage, respectively. The designed VHF-band and UHF-band variable gain amplifier show a voltage gain of 27 dB and 27 dB, a noise figure of 1.6-1.7 dB and 1.3-1.7 dB, OIP3 of 13.5 dBm and 16 dBm, respectively.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.27 no.4B
• /
• pp.331-337
• /
• 2002

In this paper we propose extended Kalman filter (EKF)-trilateration method which associates EKF to conventional radiolocation technique, trilateration in order to improve the accuracy of dynamic orbit determination of geostationary satellite for broadcasting of highly accurate Standard Time/Frequency Signal (STFS). We then compare to analyze the time accuracies of three techniques which are differential mode, trilateration locating one of four calibrated earth stations on a neighboring country, and domestic-only baseline EKF-trilateration. Computer simulations have shown that in spite of domestic-only baseline EKF-trilateration of poor GDOP, it is possible to track and locate satellite with an accuracy of a few hundred meter which is the performance 10 times more accurate than trilateration can provide. Finally we can provide standard time service with the time accuracy better than a few ns (frequency stability : 10$\^$-14/ over 7 days) all around Korea peninsula.