• Proceedings of the IEEK Conference
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• 2003.07b
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• pp.1181-1184
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• 2003

This paper proposes a new Sense Amplifier for MRAM. Current Sense Amplifier employs a latch-type circuit to amplify a signal from the selected memory cell. The proposed Sense Amplifier simplifies the circuit by amplifying the signal using cross-coupled PMOS transistors. It shows the same operation speed as the latch-type Sense Amplifier in simulation and occupies only 85% of the area taken by the latch-type Sense Amplifier.

• Journal of IKEEE
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• v.20 no.3
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• pp.279-284
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• 2016

This paper presents a two stage L-band power amplifier realized with a $0.32{\mu}m$ Silicon-On-Insulator (SOI) CMOS technology. To overcome a low breakdown voltage limit of MOSFET, stacked-FET structures are employed, where three transistors in the first stage amplifier and four transistors in the second stage amplifier are connected in series so that their output voltage swings are added in phase. The stacked-FET structures enable the proposed amplifier to achieve a 21.5 dB small-signal gain and 15.7 dBm output 1-dB compression power at 1.9 GHz with a 122 mA DC current from a 4 V supply. The amplifier delivers a 19.7 dBm. This paper presents a two stage L-band power amplifier realized with a $0.32{\mu}m$ Silicon-On-Insulator (SOI) CMOS technology. To overcome a low breakdown voltage limit of MOSFET, stacked-FET structures are employed, where three transistors in the first stage amplifier and four transistors in the second stage amplifier are connected in series so that their output voltage swings are added in phase. The stacked-FET structures enable the proposed amplifier to achieve a 21.5 dB small-signal gain and 15.7 dBm output 1-dB compression power at 1.9 GHz with a 122 mA DC current from a 4 V supply. The amplifier delivers a 19.7 dBm saturated output power with a 16 % maximum Power Added Efficiency (PAE). A bond wire fine tuning technology enables the amplifier a 23.67 dBm saturated output power with a 20.4 % maximum PAE. The die area is $1.9mm{\times}0.6mm$.

• ETRI Journal
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• v.29 no.2
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• pp.212-218
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• 2007

A novel low-voltage CMOS current feedback operational amplifier (CFOA) is presented. This realization nearly allows rail-to-rail input/output operations. Also, it provides high driving current capabilities. The CFOA operates at supply voltages of ${\pm}0.75V$ with a total standby current of 304 ${\mu}A$. The circuit exhibits a bandwidth better than 120 MHz and a current drive capability of ${\pm}1$ mA. An application of the CFOA to realize a new all-pass filter is given. PSpice simulation results using 0.25 ${\mu}m$ CMOS technology parameters for the proposed CFOA and its application are given.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.667-670
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• 1998

Novel bipolar transresistance amplifier(TRA) for high-accuracy current-mode signal processing is described. The TRA consists of two current follower for the current inputs, a current summer for curent-differential, and a voltage follower for the voltage output. The simulation results show that the impedence of the current input and the voltage output is 0.5 $\Omega$ and the 3-dB cutoff frequency when used as a current to voltage converter extends beyond 40 MHz.

• ETRI Journal
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• v.32 no.1
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• pp.151-153
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• 2010

A highly efficient linear and compactly integrated series-type Doherty power amplifier (PA) has been developed for wideband code-division multiple access handset applications. To overcome the size limit of a typical Doherty amplifier, all circuit elements, such as matching circuits and impedance transformers, are fully integrated into a single monolithic microwave integrated circuit (MMIC). The implemented PA shows a very low idle current of 25 mA and an excellent power-added efficiency of 25.1% at an output power of 19 dBm by using an extended Doherty concept. Accordingly, its average current consumption was reduced by 51% and 41% in urban and suburban environments, respectively, when compared with a class-AB PA. By adding a simple predistorter to the PA, the PA showed an adjacent channel leakage ratio better than -42 dBc over the whole output power range.

• Journal of Korea Multimedia Society
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• v.20 no.9
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• pp.1551-1558
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• 2017

Audio power amplifiers have been designed based on the premise that the impedance of loudspeakers is fixed at nominal 4 ohms or 8 ohms. However, it is known that the impedance varies with frequency and takes on the nominal value at some limited frequencies. The principle of the loudspeaker operation reveals that the sound pressure produced by the loudspeaker is proportional to the current flowing in the voice coil, not the voltage between the two terminals. We take the characteristics of the loudspeaker into account and compare the frequency responses of the loudspeaker in voltage-drive mode and current-drive mode via computer simulations, to conclude that the audio amplifier drive mode should be re-considered in an effort to improve the sound quality.

• ETRI Journal
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• v.28 no.4
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• pp.495-501
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• 2006

This paper presents a new CMOS fully-differential second-generation current conveyor (FDCCII). The proposed FDCCII is based on a fully-differential difference transconductor as an input stage and two class AB output stages. Besides the proposed FDCCII circuit operating at a supply voltage of ${\pm}1.5\;V$, it has a total standby current of $380\;{\mu}A$. The applications of the FDCCII to realize a variable gain amplifier, fully-differential integrator, and fully-differential second-order bandpass filter are given. The proposed FDCII and its applications are simulated using CMOS $0.35\;{\mu}m$ technology.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.185-188
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• 2001

This paper proposes an error amplifier circuit using OTA(Operational Transconductance Amplifier) which is the main constituent element in pulse width modulation circuit. The proposed OTA error amplifier circuit is featured by simple circuit configuration, excellent high frequency characteristics and bias current controlled output. Through the experiment of pulse width modulation circuit, the validity of the operation of the OTA error amplifier circuit is verified.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.17 no.8
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• pp.867-880
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• 1992

In this paper, a circuit design techniques for Improving the voltage gain of the GaAs MESFET single amplifier is presented. Also, various types of existing current mirror and proposed current mirror of new configuration are compared. To obtain the high differential mode gain and low common mode gain, bootstrap gain enhancement technique Is used and common mode feedback Is employed In the design of differential amplifier. The simulation results show that designed differential amplifier has differential gain of 57.66dB, unity gain frequency of 23.25GHz. Also, differential amplifier using common mode feedback with alternative negative current mirror has CMRR of 83.S8dB, stew rate of 3500 V /\ulcorners.

• Transactions on Electrical and Electronic Materials
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• v.14 no.5
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• pp.235-241
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• 2013

A low power CMOS control circuit is applied in an integrated DC-DC buck converter. The integrated converter is composed of a feedback control circuit and power block with 0.35 ${\mu}m$ CMOS process. A current-sensing circuit is integrated with the sense-FET method in the control circuit. In the current-sensing circuit, a current-mirror is used for a voltage follower in order to reduce power consumption with a smaller chip-size. The N-channel MOS acts as a switching device in the current-sensing circuit where the sensing FET is in parallel with the power MOSFET. The amplifier and comparator are designed to obtain a high gain and a fast transient time. The converter offers well-controlled output and accurately sensed inductor current. Simulation work shows that the current-sensing circuit is operated with an accuracy of higher than 90% and the transient time of the error amplifier is controlled within $75{\mu}sec$. The sensing current is in the range of a few hundred ${\mu}A$ at a frequency of 0.6~2 MHz and an input voltage of 3~5 V. The output voltage is obtained as expected with the ripple ratio within 1%.