• The Journal of Korean Institute of Communications and Information Sciences
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• v.13 no.3
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• pp.239-254
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• 1988

In this paper an exciter which performs modulation and amplification is composed of high power(30dBm) VCO(Voltage Controlled Oscillator) using push-pull circuit. Modulation is FSK using PLL(Phase Locked Loop). A single loop PLL synthesizer having sequency range of 42.5-100.5MHz, 25KHz channel spacing and switching time of 1msec converts down the exciter VCO frequency to 1.25MHz. This signal mixed with the FSK modulated signal coming in the phase detector of exciter. The acquisition time of exciter for frequency hoppng is less than 200usec, so the total acquisition time for transmission is less that 1.5msec. There is no need of additional power amplification because power amlifiction by high power VCO is high enough to communicate within near distance. The proposed frequency synthesizer is not complex so it is suitable for low cost slow frequency hopping spread spectrum communication.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.6
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• pp.591-600
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• 2010

In this paper, three kinds of 24 GHz low-power CMOS cross-coupled voltage controlled oscillators are designed and fabricated for a short-range radar applications using TSMC 0.13 ${\mu}m$ CMOS process. The basic CMOS crosscoupled voltage controlled oscillator is designed for oscillating around a center frequency of 24.1 GHz and subthreshold oscillators are developed for low power operation from it. A double resonant circuit is newly applied to the subthreshold oscillator to improve the problem that parasitic capacitance of large transistors in a subthreshold oscillator can push the oscillation frequency toward lower frequencies. The fabricated chips show the phase noise of -101~-103.5 dBc/Hz at 1 MHz offset, the output power of -11.85~-15.33 dBm and the frequency tuning range of 475~852 MHz. In terms of power consumption, the basic oscillator consumes 5.6 mW, while the subthreshold oscillator does 3.3 mW. The subthreshold oscillator with the double resonant circuit shows relatively lower power consumption and improved phase noise performance while maintaining a comparable frequency tuning range. The subthreshold oscillator with double resonances has FOM of -185.2 dBc based on 1 mW DC power reference, which is an about 3 dB improved result compared with the basic oscillator.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.12
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• pp.83-89
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• 2014

A ku-band complementary cross-coupled differential voltage controlled oscillator is designed, measured and fabricated using $0.18-{\mu}m$ CMOS technology. A 2.4GHz of very wide frequency tuning at oscillating frequency of 14.5GHz is achieved with presented circuit topology and MOS varactors. Measurement results show -1.66dBm output power with 18mA DC current drive from 3.3V power supply. When 5V is applied, the output power is increased to 0.84dBm with 47mA DC current. -74.5dBc/Hz phase noise at 100kHz offset is measured. The die area is $1.02mm{\times}0.66mm$.