• Proceedings of the IEEK Conference
• /
• 2005.11a
• /
• pp.953-956
• /
• 2005

Low voltage actuation and high isolation characteristics are key features to be solved in electrostatic RF switch design. Since these parameters in the conventional parallel plate MEMS switch design are in trade-off relation, both requirements cannot be met simultaneously. In vertical comb design, however, the actuation voltage is independent to the vertical separation distance between the contact electrodes. Then, we can design the large separation distance between contact electrodes to get high isolation. We have designed an RF MEMS switch which has -40dB isolation at 5 GHz and 6 V operation voltages. The characteristics of the fabricated switch are being evaluate.

• Proceedings of the IEEK Conference
• /
• 1998.10a
• /
• pp.1077-1080
• /
• 1998

In this paper, a simple low-power current-mode CMOS wotage reference circuit is proposed. The reference circuit of enhancement-mode MOS transistors and resistors. Temperature compensation is made by adding a current component proportional to a thermal voltage to a current component proportional to a threshold voltage. The designed circuit has been simulated using a $0.65\mu\textrm{m}$ n-well CMOS process parameters. The simulation results show that the reference circuit has a temperature coefficient less than $7.8ppm/^{\circ}C$ and a power-supply(VDD) coefficient less than 0.079%/V for a temperature range from $-30^{\circ}C$ to $130^{\circ}C$ and a VDD range from 4.0V to 12V. The power consumption is 105㎼ for VDD=5V and $T=30^{\circ}C.$ The proposed reference circuit can be designed to generate a wide range of reference voltages owing to its current-mode operation.

• Proceedings of the KIPE Conference
• /
• 2001.10a
• /
• pp.198-202
• /
• 2001

This paper presents a novel prototype version of ZCS-PWM forward DC-DC power converter using power MOSFETs which is designed for application specific low voltage large current conversion operation. The soft-switching forward power converter with a high frequency isolated transformer link which can efficiency operate over wide load ranges under two conditions of ZCS as well as active voltage clamped switching is evaluated and discussed on the basis of the simulation and experimental results.

• Proceedings of the KIEE Conference
• /
• 2001.07b
• /
• pp.660-662
• /
• 2001

This paper describes the problems generated with the use of PWM ASDs with induction motors. The major effect of harmonic voltages and currents in induction motors is increased the heating due to iron and copper losses at harmonic frequencies. The harmonic components thus affect the motor efficiency and developed the torque. In order to investigate the effect of harmonics which is caused by using of nonlinear load at the low voltage system, we set up simple load system and measured the voltage and current. Measurement results show that additional operation of induction motor at the parallel bus in using nonlinear load such as ASD is helpful to the reduction of harmonic current.

• Proceedings of the KIEE Conference
• /
• 2000.11a
• /
• pp.43-45
• /
• 2000

In this paper, portable and vehicle-mounted generators grounding methods of low-voltage systems is compared to each other. Ungrouded system is better for the safety operation than solidly grounding system. This paper also determined the magnitude and duration of the permissible body current limit and step voltage for the solidly-grounding and ungrounded system.

• Proceedings of the IEEK Conference
• /
• 2001.06b
• /
• pp.89-92
• /
• 2001

In this paper, a simple low-power CMOS current reference circuit is proposed. The reference circuit includes parasitic pnp BJTs and resistors. Temperature compensation is made by adding a current component proportional to a thermal voltage to a current component proportional to a base-to-emitter voltage. The designed circuit has been simulated using a 0.25${\mu}{\textrm}{m}$ n-well CMOS process parameters. The simulation results show that the reference current is 34.96$mutextrm{A}$$\pm$0.04$mutextrm{A}$ in the temperature range of -2$0^{\circ}C$ to 12$0^{\circ}C$ The reference current varies less than 0.6% when the power supply voltage changes from 2.5V to 3.5V For $V_{DD=5V}$ and T=3$0^{\circ}C$ the power consumption is 520㎼ during normal operation but reduces to 0.l㎻ during power-down mode.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2002.08a
• /
• pp.567-570
• /
• 2002

The LVDS (Low Voltage Differential Signaling) I/O cells, fully compatible with ANSI TIA/ EIA-644 LVDS standard, are designed using a 0.35${\mu}m$ standard CMOS technology. With a single 3V supply, the core cells operate at 1.34Gbps and power consumption of the output driver and the input receiver is 10. 5mW and 4.2mW, respectively. In the output driver, we employ the DCMFB (Dynamic Common-Mode FeedBack) circuit which can control the DC offset voltage of differential output signals. The SPICE simulation result of the proposed output driver shows that the variation of the DC offset voltage is 15.6% within a permissible range. In the input receiver, the proposed dual input stage with a positive feedback latch covers rail-to-rail input common-mode range and enables a high-speed, low-power operation. 5-channels of the proposed LVDS I/O pair can handle display data up to 8-bit gray scale and UXGA resolution.

• The Transactions of the Korean Institute of Electrical Engineers B
• /
• v.50 no.12
• /
• pp.601-608
• /
• 2001

The ever increasing density of adjustable speed drives(ASD) device with non-linear operating characteristics has been to put tremendous harmonic stress on end user's electrical application. All ASD controllers which employ solid state power devices cause harmonic currents in the source side line. This paper describes harmonic problems for use of ASD. In order to investigate the effect of harmonics caused by using of nonlinear load at the low voltage system, we fixed up simple load model and measured the voltage and current waveforms. Measurement results show that additional operation of linear load at the parallel bus with nonlinear load such as ASD is helpful to the reduction of harmonic influence.

• Proceedings of the KIEE Conference
• /
• 2001.07e
• /
• pp.13-16
• /
• 2001

This paper describes the problems associated with the use of PWM ASDs to drive induction motors. A major effect of harmonic voltages and currents in induction motors is increased heating due to iron and copper losses at harmonic frequencies. The harmonic components thus affect the motor efficiency, and can also affect the torque developed. In order to investigate the effect of harmonics which is caused by using of nonlinear load at the low voltage system, we fixed up simple load model and measured the voltage and current. Measurement. results show that additional operation of linear load at the parallel bus in using nonlinear load such as ASD is helpful to the reduction of harmonic current.

• Proceedings of the IEEK Conference
• /
• 2002.07c
• /
• pp.1555-1557
• /
• 2002

We have investigated the precharge type sense amplifier, it is suitable fur voltage sensing in a NOR type single transistor ferroelectric field effect transistor (1T FeFET) memory read operation. The proposed precharge type sense amplifier senses the bit line voltage of 1T FeFET memory. Therefore, the reference celt is not necessary compared to current sensing in 1T FeFET memory, The high noise margin is wider than the low noise margin in the first inverter because requires tile output of precharge type sense amplifier high sensitivity to transition of input signal. The precharge type sense amplifier has very simple structure and can sense the bit line signal of the 1T FeFET memory cell at low voltage.