• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.8
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• pp.1259-1265
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• 2003

We present a new post-fabrication frequency tuning method for laterally driven electrostatic microresonators using a DC-biased electrostatic comb array of linearly varied finger-length. The electrostatic tuning force and the equivalent stiffness, adjusted by the DC-biased tuning-comb array, have been formulated as functions of geometry and DC tuning voltage. A set of frequency-turnable microresonators has been designed and fabricated by 4-mask surface-micromachining process. The resonant frequency of the microfabricated microresonator has been measured for a varying tuning voltage at the reduced pressure of 1 torr. The maximum 3.3% reduction of the resonant frequency is achieved at the tuning voltage increase of 20V.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.5
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• pp.1172-1177
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• 2008

To compensate voltage error of the channel selecting filter, a current comparison type voltage tuning circuit is designed. Because the proposed current comparison type voltage tuning circuit is not need to attach another subcircuit, the chip size can be reduced, therefore the proposed circuit is very useful in the low voltage and low power channel filter. We used three channels including bluetooth communication system as application circuits of the proposed tuning circuit. As the results of HSPICE simulation using $0.18{\mu}m$ CMOS technology verify that the proposed tuning circuit respectively can be operated in $12{\mu}s$, $13{\mu}s$ and $15{\mu}s$ in three channel.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2003.11a
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• pp.234-238
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• 2003

In this work, we have designed a fully integrated 2.4GHz LC-tuned voltage-controlled oscillator (VCO) with multiple tuning inputs for a $0.25-{\mu}m$ standard CMOS Process. The design of voltage-controlled oscillator is based on an LC-resonator with a spiral inductor of octagonal type and pMOS-varactors. Only two metal layer have been used in the designed inductor. The frequency tuning is achieved by using parallel pMOS transistors as varactors and back-gate tuned pMOS transistors in an active region. Coarse tuning is achieved by using 3-bit pMOS-varactors and fine tuning is performed by using back-gate tuned pMOS transistors in the active region. When 3-bit digital and analog inputs are applied to the designed circuits, voltage-controlled oscillator shows the tuning feature of frequency range between 2.3 GHz and 2.64 GHz. At the power supply voltage of 2.5 V, phase noise is -128dBc/Hz at 3MHz offset from the carrier, Total power dissipation is 7.5 mW.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.32-36
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• 2003

In this work, we have designed a fully integrated 2.4GHz LC-tuned voltage-controlled oscillator (VCO) with multiple tuning inputs for a 0.25-$\mu\textrm{m}$ standard CMOS process. The design of voltage-controlled oscillator is based on an LC-resonator with a spiral inductor of octagonal type and pMOS-varactors. Only two metal layer have been used in the designed inductor. The frequency tuning is achieved by using parallel pMOS transistors as varactors and back-gate tuned pMOS transistors in an active region. Coarse tuning is achieved by using 3-bit pMOS-varactors and fine tuning is performed by using back-gate tuned pMOS transistors in the active region. When 3-bit digital and analog inputs are applied to the designed circuits, voltage-controlled oscillator shows the tuning feature of frequency range between 2.3 GHz and 2.64 GHz. At the power supply voltage of 2.5 V, phase noise is -128dBc/Hz at 3MHz offset from the carrier. Total power dissipation is 7.5 mW.

• 한국정보통신설비학회:학술대회논문집
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• 2009.08a
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• pp.293-297
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• 2009

In this thesis, design of a VCO(Voltage controlled Oscillator) with a novel tuning mechanism is presented for the Radar system. This circuit, the 9.5 GHz oscillator is designed and implemented by restructuring microstrip resonator to raise Q value and to require a wide frequency tuning range. This product is fabricated on 2.6 Teflon substrate and device is NE722S01. In this paper, The new microstrip resonator VCO is proposed to achieve the characteristic of a wide frequency tuning range. This microstrip resonator VCO shows the phase noise characteristic of -108.3 dBc/Hz at 1 MHz offset from the fundamental frequency, the output power of 5.7 dBm and the second harmonic suppression of -38 dBc for the VCO are obtained. The manufacture VCO shows a frequency tuning range of 193.8 MHz. The proposed micro trip resonator VCO can be used for X-band Radar System with required tuning range.

• Proceedings of the Korea Electromagnetic Engineering Society Conference
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• 2002.11a
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• pp.21-24
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• 2002

This paper presents a fully integrated, wide tuning range differential CMOS voltage-controlled oscillator, tuned by pMOS-varactors. VCO utilizing a novel tuning scheme is reported. Both coarse digital tuning and fine analog tuning are achieved using pMOS-varactors. The VCO were implemented in a 0.18-fm standard CMOS process. The VCO tuned from 1.8㎓ to 2.55㎓ through 2-bit digital and analog input. At 1.8V power supply voltage and a total power dissipation of 8mW, the VCO features a phase noise of -126㏈c/㎐ at 3㎒ frequency offset.

• JSTS:Journal of Semiconductor Technology and Science
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• v.15 no.6
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• pp.678-684
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• 2015

Near-threshold computing (NTC) is now regarded as a promising candidate for innovative power reduction, which cannot be achieved with conventional super-threshold computing (STC). However, performance degradation and vulnerability to process variation in the NTC regime are the primary concerns. In this paper, we propose a voltage- and frequency-tuning methodology for mitigating the process-variation-induced problems in NTC-based manycore architectures. To implement the proposed methodology, we build up multiple-voltage multiple-frequency (MVMF) islands and apply a voltage-frequency tuning algorithm based on the critical-path monitoring technique to reduce the effects of process variation and maximize energy efficiency in the post-silicon stage. Experimental results show that the proposed methodology reduces overall power consumption by 8.2-20.0%, compared to existing methods in variation-sensitive NTC environments.

• Journal of Power Electronics
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• v.17 no.2
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• pp.570-578
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• 2017

This paper proposes a method to stabilize the output voltage of the secondary side of an Inductive Power Transfer (IPT) system through tuning/detuning via a serial tuned DC Voltage-controlled Variable Capacitor (DVVC). The equivalent capacitance of the DVVC changes with the conduction period of a diode in the DVVC controlled by DC voltage. The output voltage of an IPT system can be made constant when this DVVC is used as a variable resonant capacitor combined with a PI controller generating DC control voltage according to the fluctuations of the output voltage. Since a passive diode instead of an active switch is used in the DVVC, there are no active switch driving problems such as a separate voltage source or gate drivers, which makes the DVVC especially advantageous when used at the secondary side of an IPT system. Moreover, since the equivalent capacitance of the DVVC can be controlled smoothly with a DC voltage and the passive diode generates less EMI than active switches, the DVVC has the potential to be used at much higher frequencies than traditional switch mode capacitors.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.33A no.2
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• pp.78-86
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• 1996

Solid-state devices can be directly integrated with a planar antenna to form active antenna elements. In this paper, the voltage controlled oscillator (VCO) is designed and fabricated at 2.4 to 2.5 GHz using a microstrip patch antenna. A varactor diode is used as avariable reactance. The predicted frequency tuning range of the VCO is 2.448 to 2.498 GHz in the design procedure and the fabricated VCO has 2.446 to 2.498 GHz frequency tuning range when the varactor tuning voltage is varied from 0 to 11V. Transmitted power output of the patch antenna which serves both as a rsonator and a radiating element for VCO is about 18 mW over this tuning range.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.5A
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• pp.513-518
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• 2010

Improvement of phase noise characteristics in a different approach of HEMT VCO (Voltage Controlled Oscillator) with coupled microstrip lines to tune the oscillating frequency is investigated. Two HEMT VCOs of 9.8GHz are manufactured in the same configuration except for the frequency tuning circuit in order to empirically demonstrate the phase noise reduction. Experimental result shows that phase noise reduction can be enhanced 8dBc/Hz at 100KHz offset frequency from carrier by frequency tuning circuit with coupled microstrip lines over the conventional VCO.