• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.825-828
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• 2005

In this paper, we propose a new nonvolatile unit memory cell and proposal peripheral circuit using the polymer material. Memory that relies on bistable behavior- having tow states associated with different resistances at the same applied voltage - has attracted much interest because of its nonvolatile properties. Such memory may also have other merits, including simplicity of structure and manufacturing, and the small size of memory cells. We have plotted the load line graphs for the use of a polymer memory character, hence we have designed in the band-gap reference shape of a write/erase drive, and then designed in the 2-stage differential amplifier shape of a sense amplifier in the consideration of a low current characteristic of a polymer memory cell. The simulation result shows that is has high gain about 80dB by sensing the very small current.

• JSTS:Journal of Semiconductor Technology and Science
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• v.12 no.3
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• pp.313-319
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• 2012

The power supply rejection (PSR) of low drop-out (LDO) voltage regulator is improved by employing an error amplifier (EA) which is configured so the power supply noise be cancelled at the output. The LDO regulator is implemented in a 0.13-${\mu}m$ standard CMOS technology. The external supply voltage level is 1.2-V and the output is 1.0-V while the load current can range from 0-mA to 50-mA. The power supply rejection is 46-dB, 49-dB, and 38-dB at DC, 2-MHz, and 10-MHz, respectively. The quiescent current consumption is 65-${\mu}A$.

• The Transactions of the Korean Institute of Electrical Engineers A
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• v.49 no.9
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• pp.459-466
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• 2000

The performance of a commercialized power system stabilizer (PWX-600) for a single hydro-turbine generator and infinite bus system has been investigated using Real Time Digital Simulator (RTDS) in this paper. The test system was composed of RTDS, three phase voltage/current amplifier and the PSS. The test scheme provided a very efficient way to verify the design and control performance of a PSS to be applied to real power system. The scheme can also be applied to verify in real time the performance of hardware and software of power system controllers for FACTS and protective relays effectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.14 no.2
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• pp.89-95
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• 1978

A SCR static breaker was studied on the Resistive and inductive load, then on the overload break circuit using operational Amplifier. In this paper, the principal circuit required for forced commutation was voltage commutation by the introduction of a parallel Capacitor. The results obtained are follows; 1. In thecondition that the tima constant of R-C circuit is larger than the turn off time of SCR, the breaker has low transient phenomena and no recovery vol age. 2. By using OP Amplifier on the load circuit, overcurrent trip point will be able to adjust to the wide range of over current. 3. In the over current qrcuit, the power loss was reduced remarkably.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.91-94
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• 2002

This paper presents a novel active common-mode EMI filter for the PWM inverter application. The proposed filter is based on the current sensing and compensation circuit and it utilizes a fast transistor amplifier for the current compensation. The amplifier utilizes an isolated low-voltage dc power supply for its biasing and it is possible to construct the active filter independent of the source voltage of the equipment. Thus the proposed active filter can be used in any application regardless of its working voltage. The effectiveness of the proposed circuit is verified by experimental results.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.986-989
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• 1999

An 12bit current-mode folding and interpolation analog to digital converter (ADC) with multiplied folding amplifiers is proposed in this paper. A current - mode multiplied folding amplifier is employed not only to reduced the number of reference current source, but also to decrease a power dissipation within the ADC. The designed ADC fabricated by a 0.6${\mu}{\textrm}{m}$ n-well CMOS double metal/single poly process. The simulation result shows the power dissipation of 280㎽ with a power supply of 5V.

• Journal of Power Electronics
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• v.16 no.1
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• pp.362-373
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• 2016

The on-line measurement of high-power IGBT collector current is important for the hierarchical control and short-circuit and overcurrent protection of its driver and the sensorless control of the converter. The conventional on-line measurement methods for IGBT collector current are not suitable for engineering measurement due to their large-size, high-cost, low-efficiency sensors, current transformers or dividers, etc. Based on the gate driver, this paper has proposed a current measuring circuit for IGBT collector current. The circuit is used to conduct non-intervention on-line measurement of IGBT collector current by detecting the voltage drop of the IGBT power emitter and the auxiliary emitter terminals. A theoretical analysis verifies the feasibility of this circuit. The circuit adopts an operational amplifier for impedance isolation to prevent the measuring circuit from affecting the dynamic performance of the IGBT. Due to using the scheme for integration first and amplification afterwards, the difficult problem of achieving high accuracy in the transient-state and on-state measurement of the voltage between the terminals of IGBT power emitter and the auxiliary emitter (u_Ee) has been solved. This is impossible for a conventional detector. On this basis, the adoption of a two-stage operational amplifier can better meet the requirements of high bandwidth measurement under the conditions of a small signal with a large gain. Finally, various experiments have been carried out under the conditions of several typical loads (resistance-inductance load, resistance load and inductance load), different IGBT junction temperatures, soft short-circuits and hard short-circuits for the on-line measurement of IGBT collector current. This is aided by the capacitor voltage which is the integration result of the voltage uEe. The results show that the proposed method of measuring IGBT collector current is feasible and effective.

• Journal of IKEEE
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• v.18 no.1
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• pp.37-44
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• 2014

In this paper we present an LDO based on an error amplifier. The designed error amplifier has a gain of 89.93dB at low frequencies. This amplifier's Bandwidth is 50.8MHz and its phase margin is $59.2^{\circ}C$. Also we proposed a BGR. This BGR has a low output variation with temperature and its PSRR at 1 KHz is -71.5dB. For a temperature variation from $-40^{\circ}C$ to $125^{\circ}C$ we have just 9.4mV variation in 3.3V LDO output. Also it is stable for a wide range of output load currents [0-200mA] and a $1{\mu}F$ output capacitor and its line regulation and especially load regulation is very small comparing other papers. The PSRR of proposed LDO is -61.16dB at 1 KHz. Also we designed it for several output voltages by using a ladder of resistors, transmission gates and a decoder. Low power consumption is the other superiority of this LDO which is just 1.55mW in full load. The circuit was designed in $0.35{\mu}m$ CMOS process.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1A
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• pp.11-15
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• 2006

A pre-amplified semiconductor optical amplifier-Mach-Zehnder interferometer(SOA-MZI) wavelength converter (WC) using a continuous wave-holding beam(CW-HB) is proposed and experimentally demonstrated at 10Gb/s. The proposed scheme achieves not only enhancement of input power dynamic range(IPDR) to over 20dB but also higher Q parameter of about 2 to 3 by no output signal distortion and higher extinction ratio(ER) of about 2dB to 5dB by low noise figure (NF), compared with the bias current control method.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.9 no.3
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• pp.647-653
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• 2005

According to the design concept of microwave front-end, a low noise amplifier block using HBT cascode topology is proposed to provide high gain and low noise figure with low bias current. We has implemented MMIC-LNA with a modified configuration using inductors to show low noise at the emitter and base of cascoded HBT-MMIC amplifier. The measured performance of the designed MMIC-LNA at 3.7GHz are a gain of 19dB, noise figure of 2.7dB and image rejection of 35dBc using a supply of 3mA and 2.7V. We can convinced that cascoded amplifier block to fulfill a high gain, low noise and image rejection if microwave front-end receiver is designed by cascode MMEC-LNA with the active image rejection filter.