• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.2
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• pp.106-111
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• 2015

Since most reference voltage generator circuits have bi-stable characteristics, it is important to employ a proper start-up circuit to operate a reference generator in the desired state. In this paper, we propose a start-up circuit for a low voltage reference generator. This start-up circuit determines the state of the circuit reliably by measuring the current drawn by BJTs in the circuit, which is well-defined in the desired state. To measure the current using CMOS-compatible devices only, a comparator with an internal offset voltage is used. The reliability of the proposed circuit is confirmed by Monte-Carlo simulations of the start-up operation, which show that, with the proposed start-up circuit, the low voltage reference generator starts reliably with supply voltages over 850mV even in the presence of device mismatches.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.46 no.6
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• pp.52-57
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• 2009

This paper presents a low-noise low-dropout linear regulator that is suitable for on-chip integration with RF transceiver ICs. In the bandgap reference, a stacked diode structure is adopted for saving silicon area as well as maintaining low output noise characteristic. Theoretical analysis for supporting the approach is also described. The linear regulator is fabricated in $0.18{\mu}m$ CMOS process. It operates with an input voltage range of 2.2 V - 5 V and provide the output voltage of 1.8 V and the output current up to 90 mA. The measured line and load regulation is 0.04%/V and 0.46%, respectively. The output noise voltage is measured to be 479 nV/$^\surd{Hz}$ and 186 nV/$^\surd{Hz}$ from 100 Hz and 1 kHz offset, respectively.

• Korea Science and Art Forum
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• v.20
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• pp.421-428
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• 2015

Electronic/hybrid car and electroplating rectifier should have switching devices such as SCR, MOSFET, IGBT. And those switching devices should be operated by gate driver. In this paper, we propose high power gate driver that contains H-Bridge using 4 BJTs. H-Bridge and transformer generate isolate power. And gate control signal is transferred to isolated one by photo coupler and operate real switching device. We designed H-Bridge and 555-Timer by PSpice simulation and manufactured real product. Finally we succeed to operate 27V 50,000A electroplating rectifier using proposed gate driver.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.19 no.11
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• pp.1193-1203
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• 2008

An active antenna(AA) can have wider bandwidth and more gain with small antenna size than those of passive antennas. However, AA inherently generates thermal noise and spurious signals from an active device. Moreover, the spurious performance of AA is very important in a highly sensitive receiving system since it is located at the front end of the receiving system. In this study, we developed an AA with $100{\sim}500\;MHz$, having the output P1dB higher than 3 dBm and little spurious signals in real environments. To achieve such performance, we designed an AA with 3-stage amplifier using CD(common drain) FET and 2 BJTs. Its electrical performances were simulated using ADS. The measurement results for typical gain, NF, OIP3, VSWR and P1dB in the required frequency band were 9.7 dBi, 10 dB, 14 dBm, 1.7:1 and 3 dBm respectively. They are in good agreement with simulation results. The unwanted spectrum level of the proposed AA is $10{\sim}30\;dB$ lower than that of the antenna with CS(common source) FET configuration at a west suburban area of Seoul, which shows that the proposed AA can be applicable to a highly sensitive receiving system for detecting unknown weak signals mixed with broadcasting and civilian communication signals.