• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.100-103
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• 2003

A Ku-band Push-push VCO for low cost applications is proposed. The proposed push-push oscillator achieves a wide tuning range in Ku-band by the collector bias tuning instead of extra varactor diodes. The measurement shows a wide tuning range of 900MHz, fundamental suppression of -30dBc and good phase noise of -115dBc@1MHz offset.

• Proceedings of the IEEK Conference
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• summer
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• pp.218-220
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• 2004

A new wide-band VCO topology using Miller capacitance is proposed. Contrary to conventional VCO using the Miller capacitance where the variable amplifier gain is negative, the proposed VCO uses both the negative and positive variable amplifier gain to enhance the frequency tuning range significantly. The proposed VCO is simulated using HSPICE. The simulations show that 410MHz and 220MHz frequency tuning range are obtained using the negative .and positive variable amplifier gain, respectively. The tuning range of the proposed VCO is $23\%$ of the center frequency(2.8GHz). The phase noise is -104dBc/Hz at 1MHz offset by simple model. The operating current is only 3.84mA at 2.5V power supply.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.6
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• pp.570-579
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• 2009

In this paper, we presented a Vt-DRO with a wide electrical frequency tuning range, using open-loop gain method. The Vt-DRO was composed of 3-stages, resonator, amplifier and phase shifter. In order to satisfy an oscillation condition, we determined magnitude and phase of each stage. The measured S-parameter of cascaded 3-stages shows open-loop oscillation condition. Also, using measured open loop group delay, we derived the relation for electrical frequency tuning range. The Vt-DRO was implemented by connecting the input and the output of the designed open-loop and resulted in closed-loop. As a results, tuning-range of Vt-DRO is 82 MHz, which is close to the predicted results for tuning voltage 0${\sim}$10 V and shows linear frequency tuning at the center frequency of 5.3 GHz. The phase noise is -104 ${\pm}$1 dBc/Hz at 100 kHz offset frequency and power is 5.86${\pm}$1 dBm respectively.

• JSTS:Journal of Semiconductor Technology and Science
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• v.13 no.3
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• pp.198-206
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• 2013

This paper presents a wide band, fine-resolution digitally controlled oscillator (DCO) with an on-chip 3-D solenoid inductor using the 0.13 ${\mu}m$ digital CMOS process. The on-chip solenoid inductor is vertically constructed by using Metal and Via layers with a horizontal scalability. Compared to a spiral inductor, it has the advantage of occupying a small area and this is due to its 3-D structure. To control the frequency of the DCO, active capacitor and active inductor are tuned digitally. To cover the wide tuning range, a three-step coarse tuning scheme is used. In addition, the DCO gain needs to be calibrated digitally to compensate for gain variations. The DCO with solenoid inductor is fabricated in 0.13 ${\mu}m$ process and the die area of the solenoid inductor is 0.013 $mm^2$. The DCO tuning range is about 54 % at 4.1 GHz, and the power consumption is 6.6 mW from a 1.2 V supply voltage. An effective frequency resolution is 0.14 kHz. The measured phase noise of the DCO output at 5.195 GHz is -110.61 dBc/Hz at 1 MHz offset.

• Journal of Institute of Control, Robotics and Systems
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• v.12 no.12
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• pp.1173-1177
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• 2006

Using an inner P controller, a tuning rule useful for processes with wide ratios of time delay over time constant is proposed. Internal model control method and pole assignment method are utilized. It can be used for processes with wide range of the ratio of time delay to time constant without incovenience to choose different tuning rules.

• Journal of Power Electronics
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• v.18 no.2
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• pp.640-650
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• 2018

A TRIAC dimmable LED driver with a wide tuning range and a two-stage uniform dimming scheme is proposed in this paper. To solve the restricted dimming range problem caused by the limited conduction ratio of TRIAC dimmers, a conduction ratio compensation technique is introduced, which can increase the output current up to the rated output current when the TRIAC dimmer turns to the maximum conduction ratio. For further optimization, a two-stage uniform dimming diagram with a rapid dimming curve and a slow dimming curve is designed to make the LED driver regulated visually uniform in the whole adjustable range of the TRIAC dimmer. The proposed control chip is fabricated in a TSMC $0.35{\mu}m$ 5V/650V CMOS/LDMOS process, and verified on a 21V/500mA circuit prototype. The test results show that, in the 90V/60Hz~132V/60Hz ac input range, the voltage linear regulation is 2.6%, the power factor is 99.5% and the efficiency is 83%. Moreover, in the dimming mode, the dimming rate is less than 1% when the maximum dimming current is 516mA and the minimum dimming current is only about 5mA.

• IEIE Transactions on Smart Processing and Computing
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• v.4 no.3
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• pp.158-162
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• 2015

A low phase noise CMOS voltage controlled oscillator(VCO) for multi-band/multi-standard RF Transceivers is presented. For both wide tunability and low phase noise characteristics, Hybrid inductor which uses both bondwire inductor and planar spiral inductor in the same area, is proposed. This approach reduces inductance variation and presents high quality factor without custom-designed single-turn inductor occupying large area, which improves phase noise and tuning range characteristics without additional area loss. An LC VCO is designed in a 0.13um CMOS technology to demonstrate the hybrid inductor concept. The measured phase noise is -121dBc/Hz at 400KHz offset and -142dBc/Hz at 3MHz offset from a 900MHz carrier frequency after divider. The tuning range of about 28%(3.15 to 4.18GHz) is measured. The VCO consumes 7.5mA from 1.3V supply and meets the requirements for GSM/EDGE and WCDMA standard.

• Journal of electromagnetic engineering and science
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• v.11 no.4
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• pp.235-238
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• 2011

In this paper, a novel low phase noise voltage-controlled oscillator (VCO) using metamaterial structure and rat race coupler is presented for reducing the phase noise without the reduction of the frequency tuning range. The metamaterial structure has been realized by microstrip square open loop double split ring resonator (SRR). The rat race coupler shows slightly higher transmission compared to a Wilkinson combiner and is, therefore, used instead to improve the performances of VCO. By providing these unique modifications, the proposed push-push VCO has a phase noise of -126.30~-124.83 dBc/Hz at 100 kHz in the tuning range of 5.672~5.800 GHz.

• Korean Journal of Optics and Photonics
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• v.12 no.4
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• pp.257-262
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• 2001

A Littman type tunable external-cavity diode laser system was developed. The laser output which is the Oth-order diffracted beam from a diffraction grating in an external cavity is a single longitudinal mode. Its FWHM was measured as less than 9 MHz. With the diode driving current of 140 mA and operating temperature of $25^{\circ}C$, the coarse tuning range of 3.475 urn was measured. A fine tuning experiment in which an external mirror was rotated by a PZT driven by a sawtooth wave was performed, and its tuning range of 0.042 urn was measured. sured.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.5
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• pp.35-40
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• 2005

An experimental Investigation of the basic characteristics of a micro-cantilever sensor was performed by inspecting the amplitude and frequency characteristics of a commercial tuning fork (TF). Application of acetone and ethanol with a volume of $1{\mu}l$ on the tine of a vibrating tuning fork causes immediate response in its amplitude and frequency characteristics. It has been shown that the tuning fork has ability to recognize a chemical agent with high sensitivity. The theoretical sensitivity of mass loading is in the range of $\~0.1Hz/ng$. Quartz tuning forks are routinely made using standard microfabrication process, thus suggesting the possibility of microfabrication of micro quart sensors.