• Proceedings of the IEEK Conference
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• 2000.11a
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• pp.381-384
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• 2000

In this paper, we designed and fabricated a low noise amplifier which can be used in W-CDMA. For improving input VSWR and stability an emitter inductance series feedback was used, and for acquiring higer linearity at low current DC bais by-passing method was used. Fabricated low noise amplifier had 15.33 ㏈ power gain, 2.17 ㏈ NF, -9.53 ㏈ $S_{11}$ and -35.91 ㏈ $S_{22}$ at 2.16 GHz, and +5.34 ㏈m II $P_{ 3}$ at 10 MHz channel spacing.g.g.g.

• Proceedings of the KIPE Conference
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• 2020.08a
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• pp.459-460
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• 2020

The design of a low distortion class E amplifier with a frequency of 6.78MHz for a wireless power transfer is presented. The amplifier with a differential out is designed to reduce the harmonics of the output current. The harmonic characteristics of various types of the class E amplifiers are compared through the simulation study.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.13 no.9
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• pp.882-888
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• 2002

This paper proposed a bias stability circuit that compensates the degradation of MMIC's performance for the variation of the process and temperature. The proposed bias circuit proved the superior effect compared with the conventional bias circuit using the constant current source. It designed and fabricated simultaneously two amplifier on one layout for comparison in same conditions. One is amplifier with conventional bias circuit using constant current source and the other is amplifier with proposed bias stability circuit. The chip was measured the microwave performances under process variation that classed the level NOM, MIN and MAX. The amplifier with a conventional bias circuit using constant current source has 6.4 dB gain variation and 7 mA Ids variation at 1.8 GHz, but the amplifier with the proposed bias circuit has the 2.1 dB gain variation and 3 mA Ids variation. As the result, MMIC having the proposed bias circuit shows the superior compensation of the quiescent point than the MMIC having the conventional bias circuit under the variations of the process and temperature and can improve the yield of the MMIC. The fabricated chip size is 1.2 mm $\times$ 1.4 mm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.5
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• pp.624-631
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• 2012

This paper presents a high-efficiency current mode class-D(CMCD) power amplifier for the 13.56 MHz band using a Guanella's 1:1 transmission-line transformer and filtering circuits at the output network. The second and third s are filtered out in the load network of the class-D amplifier. The implemented CMCD power amplifier exhibited a power gain of 13.4 dB and a high power-added efficiency(PAE) of 84.6 % at an output power of 44.4 dBm using the 13.56 MHz CW input signal. The second and third distortion levels were -50.3 dBc and -46.4 dBc at the same output power level, respectively.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.10
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• pp.63-67
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• 2003

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

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

• Current Optics and Photonics
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• v.7 no.1
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• pp.33-37
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• 2023

Real-time adaptive control of laser output polarization is presented in a 10-W-level non-polarization-maintaining (non-PM) fiber amplifier. While the output polarization from a non-PM fiber amplifier tends to be irregular, depending on output power, time, and perturbation, closed-loop polarization control can maintain the polarization extinction ratio at higher than 20 dB. Real-time polarization control can attain the target linear polarization mostly within 1.4-25 ms and shows stability against external perturbations. This approach can satisfy both linear polarization and high output power in a non-PM amplifier, and facilitates optimization of laser performance and maintenance-free operation.

• Journal of Korea Multimedia Society
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• v.21 no.9
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• pp.1068-1075
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• 2018

We propose a method for driving loudspeakers from class D audio power amplifiers in current mode, instead of in conventional voltage mode, which was impossible with the feedback circuitry. Unlike analog audio amplifiers, Class D audio power amplifiers have signal delay between the input and output signals, which makes it difficult to apply the feedback circuitry for current-mode driving. The idea of the pre-distortion scheme used for the compensation of the non-linearity of RF power amplifiers is adapted to remedy the impedance variation effect of the loudspeakers for current driving. The method uses the speaker model for the pre-distorter to compensate for the speaker impedance variation with frequency. The simulation and test results confirms the validity of the proposed method.

• Journal of Advanced Information Technology and Convergence
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• v.8 no.2
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• pp.59-67
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• 2018

The minimum power supply voltage of a typical bandgap current reference (BGCR) is limited by operating temperature and input common mode range (ICMR) of a feedback amplifier. A new BGCR using a bandgap voltage generator (BGVG) is proposed to minimize the effect of temperature, supply voltage, and process variation. The BGVG is designed with proportional to absolute temperature (PTAT) characteristic, and a feedback amplifier is designed with weak-inversion transistors for low voltage operation. It is verified with a $0.18-{\mu}m$ CMOS process with five corners for MOS transistors and three corners for BJTs. The proposed circuit is superior to other reported current references under temperature variation from $-40^{\circ}C$ to $120^{\circ}C$ and power supply variation from 1.2 V to 1.8 V. The total power consumption is $126{\mu}W$ under the conditions that the power supply voltage is 1.2 V, the output current is $10{\mu}A$, and the operating temperature is $20^{\circ}C$.

• ETRI Journal
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• v.31 no.5
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• pp.601-603
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• 2009

This letter presents a high performance 2.4 GHz two-stage power amplifier (PA) operating in the temperature range from $-30^{\circ}C$ to $+85^{\circ}C$ for IEEE 802.11g, wireless local area network application. It is implemented in InGaP/GaAs hetero-junction bipolar transistor technology and has a bias circuit employing a temperature compensation technique for error vector magnitude (EVM) performance. The technique uses a resistor made with a base layer of HBT. The design improves EVM performance in cold temperatures by increasing current. The implemented PA has a dynamic EVM of less than 4%, a gain of over 26 dB, and a current less than 130 mA below the output power of 19 dBm across the temperature range from $-30^{\circ}C$ to $+85^{\circ}C$.