• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.10
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• pp.14-23
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• 1997

An MMIC downconverting mixer for cellular phone application has been successfully developed using an MMIC process including $1 \mu\textrm{m}$ ion implanted gaAs MESFET and passive lumped elements consisting of spiral inductor, $Si_3N_4$ MIM capacitor and NiCr resistor. The configuration of the mixer presented in this paper is single-ended dual-gate FET mixer with common-source self-bias circuits for single power supply operation. The dimension of the fabricated circuit is $1.4 mm \times 1.03 mm $ including all input matching circuits and a mixing circuit. The conversion gian and noise figure of the mixer at LO powr of 0 dBm are 5.5dB and 19dB, respectively. The two-tone IM3 characteristics are also measured, showing -60dBc at RF power of -30dBm. Allisolations between each port show better than 20dB.

• Proceedings of the IEEK Conference
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• 2002.06b
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• pp.145-148
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• 2002

In this paper, a voltage controlled oscillator (VCO) with automatic amplitude control is designed using a 0.35${\mu}{\textrm}{m}$ CMOS process. A cross-coupled PMOS pair is used for a negative resistance to compensate for the losses in the LC resonator, and an automatic\ulcorner amplitude control function is adapted to provide constant output power independent of the Q-factor of the LC resonator. The designed VCO operates in the 200MHz to 550MHz frequency range using different external resonators. The simulated phase noise is -128 dBc/Hz at 100KHz offset from the carrier frequency of 260MHz. It dissipates 0.㎽ from a 3V power supply. The area is 300${\mu}{\textrm}{m}$ x1201${\mu}{\textrm}{m}$.

• Proceedings of the KSR Conference
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• 2007.05a
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• pp.964-967
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• 2007

Tilting trains are now an established feature of railway operations throughout the world. For intercity traffic, tilt provides operators with increasing speeds, and therefore enhanced competitiveness, on existing routes where insufficient traffic or a lack of funds precludes the construction of a dedicated new high-speed railway. Appling the tilting train, we can expect 30% of speed up on existing lines, but the stability of the electric current would be low because of tilting the train. Also, the spark between the catenary and pantagraph cause environmental problems such as noise, radio wave malfunction. Therefore, the tilting on pantagraph for the power suppling device is very essential for stable electric power supply.

• Proceedings of the IEEK Conference
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• 2002.06e
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• pp.231-234
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• 2002

In this paper, we propose an efficient bias circuit for hearing aid using discrete BJT. The collector feedback bias circuit, widely used for the hearing aid, has a resister for negative feedback. As the resistor affects AC and DC simultaneously, it is quite difficult to adjust amplifier gain without changing DC bias point. The previous bias circuit also has weak point to be oscillated by the positive feedback of power noise if gain of hearing aid is high. In the proposed circuit, we can reduce the two weak points of the previous circuit by adding a resistor which is ${\beta}$ times larger than collector resistor between base of BJT and power supply.

• Proceedings of the KIEE Conference
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• 2004.04a
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• pp.229-231
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• 2004

Tilting trains are now an established feature of railway operations throughout the world. For intercity traffic, tilt provides operators with increasing speeds, and therefore enhanced competitiveness, on existing routes where insufficient traffic or a lack of funds precludes the construction of a dedicated new high-speed railway. Appling the tilting train, we can expect 30% of speed up on existing lines, but the stability of the electric current would be low because of tilting the train. Also, the spark between the catenary and pantagraph cause environmental problems such as noise, radio wave malfunction. Therefore, the tilting on pantagraph for the power suppling device is very essential for stable electric power supply.

• Proceedings of the KIEE Conference
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• 2002.11c
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• pp.609-612
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• 2002

In this paper, a 12-bit 100-MHz CMOS current steering digital-to-analog converter is designed. In the D/A converter, a driver circuit using a dynamic latch is implemented to obtain low glitch and thermometer decoder is used for low DNL errors, guaranteed monotonicity, reduced stitching noise. And a threshold voltage-compensated current source. The D/A converter is designed with 0.35-$\mu m$ CMOS technology at 3.3 V power supply and simulated with HSPICE. The maximum power dissipation of the designed DAC is 143 mW.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1109-1111
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• 2006

Tilting trains are now an established feature of railway operations throughout the world. For intercity traffic, tilt provides operators with increasing speeds, and therefore enhanced competitiveness, on existing routes where insufficient traffic or a lack of funds precludes the construction of a dedicated new high-speed railway. Appling the tilting train, we can expect 30% of speed up on existing lines, but the stability of the electric current would be low because of tilting the train. Also, the spark between the catenary and pantagraph cause environmental problems such as noise, radio wave malfunction. Therefore, the tilting on pantagraph for the power suppling device is very essential for stable electric power supply.

• ETRI Journal
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• v.33 no.3
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• pp.393-400
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• 2011

A systematic approach for the design of two-stage class AB CMOS unity-gain buffers is proposed. It is based on the inclusion of a class AB operation to class A Miller amplifier topologies in unity-gain negative feedback by a simple technique that does not modify quiescent currents, supply requirements, noise performance, or static power. Three design examples are fabricated in a 0.5 ${\mu}m$ CMOS process. Measurement results show slew rate improvement factors of approximately 100 for the class AB buffers versus their class A counterparts for the same quiescent power consumption (< 200 ${\mu}W$).

• Proceedings of the KIEE Conference
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• 2005.04a
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• pp.253-255
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• 2005

Tilting trains are now an established feature of railway operations throughout the world. For intercity traffic, tilt provides operators with increasing speeds, and therefore enhanced competitiveness, on existing routes where insufficient traffic or a lack of funds precludes the construction of a dedicated new high-speed railway. Appling the tilting train, we can expect 30% of speed up on existing lines, but the stability of the electric current would be low because of tilting the train. Also, the spark between the catenary and pantagraph cause environmental problems such as noise, radio wave malfunction. Therefore, the tilting on pantagraph for the power suppling device is very essential for stable electric power supply.

• ETRI Journal
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• v.26 no.5
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• pp.486-492
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• 2004

The emergence of wide channel bandwidth wireless standards requires the use of a highly linear, wideband integrated CMOS baseband chain with moderate power consumption. In this paper, we present the design of highly linear, wideband active RC filters and a digitally programmable variable gain amplifier. To achieve a high unity gain bandwidth product with moderate power consumption, the feed-forward compensation technique is applied for the design of wideband active RC filters. Measured results from a $0.5{\mu}m$ CMOS prototype baseband chain show a cutoff frequency of 10 MHz, a variable gain range of 33 dB, an in-band IIP3 of 13 dBV, and an input referred noise of 114 ${\mu}Vrms$ while dissipating 20 mW from a 3 V supply.