• The Transactions of the Korean Institute of Electrical Engineers D
• /
• v.53 no.10
• /
• pp.727-732
• /
• 2004

TCXO is one of the most important component in communication systems. We present a analytic method approach to design the Temperature Compensated Circuit. The conventional method for extracting the circuit parameters, which are for thermistor, Colpitts and frequency control circuit is the trial and error correction. In this paper, we analyse the temperature compensating circuit to extract TCXO circuit parameter. In order to show the validity of this paper, we have designed and implemented the 10MHz TCXO. The fabricated TCXO shows 1ppm frequency drift characteristic over the temperature range of -40℃∼85℃.

• Proceedings of the IEEK Conference
• /
• 1999.06a
• /
• pp.183-186
• /
• 1999

The Ultra-miniature and low phase noise Colpitts VCO of 0.06㏄ in size has been developed using the high Q resonator and phase compensation technique. This type is one transistor VCO without a buffer. To design and simulate the VCO accurately, nolinear model parameters of a bipolar transistor are extracted using the measured I-V data and S parameters based on the Gummel-Poon model. Design and simulation have been done by Serenade 7.5 design tool using the extracted nonlinear model parameters. The wideband VCO has been designed using two varactor diodes and open loop gain compensation technique to improve the operating frequency range. The ultra-miniature VCO has shown the phase noise of -91㏈c/Hz at 10KHz offset and output power of -3㏈m The wideband VCO has shown the tuning frequency bandwidth of 150MHz phase noise of -95㏈c/Hz at 10KHz offset and output power of 5㏈m.

• Proceedings of the IEEK Conference
• /
• 2003.11c
• /
• pp.37-40
• /
• 2003

The 1.63㎓, 2.33㎓ dual-band PLL frequency synthesizer has been developed for applications to the miniature repeater. The miniature dual-band repeater will be used at shopping mall, basements and underground parking lots. The in-loop 1.63㎓, 2.33㎓ dual-band PLL frequency synthesizer has been developed by designing Si BJT VCO and PLL loop circuits with Colpitts. The prototype of 1.63㎓, 2.33㎓ dual-band PLL frequency synthesizer of size 19${\times}$19${\times}$8(mm) has shown operating frequencies of 1.63㎓, 2.33㎓ ranges, RF output of 1dBm(PCS), 1dBm(IMT-2000), phase noise of -100 dBc/Hz(PCS), -95dBc/Hz(IMT-2000) at 10KHz offset, harmonics suppression of -24dB c(PCS), -15dBc(IMT-2000).

• Journal of IKEEE
• /
• v.19 no.4
• /
• pp.465-471
• /
• 2015

An LC-tuned sinusoidal voltage-controlled oscillator (VCO) using temperature-stable linear operational transconductance amplifiers (OTAs) is presented. Its architecture is based on Hartley oscillator configuration, where the inductor is active one realized with two OTAs and a grounded capacitor. Two diode limiters are used for limiting amplitude. A prototype oscillator built with discrete components exhibits less than 3.1% nonlinearity in its current-to-frequency transfer characteristic from 1.99 MHz to 39.14 MHz and $220ppm/^{\circ}C$ frequency stability to the temperature drift over 0 to $75^{\circ}C$. The total harmonic distortion (THD) is as low as 4.4 % for a specified frequency-tuning range. The simulated phase noise of the VCO is about -108.9 dBc/Hz at 1 MHz offset frequency in frequency range of 0.4 - 46.97 MHz and property of phase noise of VCO is better than colpitts-VCO.

• Proceedings of the KIEE Conference
• /
• 2005.07c
• /
• pp.2333-2335
• /
• 2005

Various CMOS quadrature-voltage-controlled oscillators(QVCOs) are designed and fabricated for the comparison of the phase noise. The core VCO is composed of two Colpitts oscillators which are cross-coupled with PMOS pair. For the comparison of phase noise with the proposed scheme, the conventional LC VCO followed by the frequency-divide-by-two is designed. The simulation result demonstrate that the proposed scheme shows better phase noise performance by 6dB than that of a conventional scheme in which LC VCO is followed by the frequency-divide-by-two.

• Proceedings of the KIEE Conference
• /
• 2005.07b
• /
• pp.1506-1508
• /
• 2005

VCO(voltage controlled oscillator) using mobile communication device decides direct characteristics as parts that affect important in stable oscillation and distortion characteristics of system. VCO used 900 MHz band was designed by the transformation of Colpitts circuit form use ADS that consider Q-factor to minimize phase noise. VCO manufactured together evaluation board and voltage control oscillator to FR-4 PCB. VCO experimented chracteristics after control through resonance department tuning. In our research, the designed VCO has 15.5 dBm output level at the bias condition of 6V and 10mA and the operating frequency range of 917 MHz$\sim$937 MHz band. Phase noise is -98.28 dBc/Hz at 1 MHz frequency offset from the carrier.

• Agricultural and Biosystems Engineering
• /
• v.2 no.2
• /
• pp.63-68
• /
• 2001

The objective of this study was to develop a real-time soil moisture meter using RF impedance. The impedance suchas capacitance and resistance (or conductance) was analyzed using parallel cylinder type capacitance probe(C-probe) and Q-meter (HP4342). The capacitance and conductance of soil increased as volumetric water content increased. The 5 MHz of modified Colpitts type crystal oscillator was designed to detect the capacitance change of the C-probe with moist soil. A third order polynomial regression model was proposed to describe the relationship between RF impedance and volumetric water content. The prototype real time moisture meter consisted of the C-probe, sample container, oscillator, frequency counter and related signal processing units. The calibration equation for measurement of volumetric moisture content of soil was developed and validated. The correlation coefficient and root mean square error between measured volumetric water content by oven method and predicted values by prototype moisture meter for unknown soil samples were 0.984 and 0.032$cm^3$$cm\^3$, respectively.

• Proceedings of the KIEE Conference
• /
• 1987.07b
• /
• pp.1163-1165
• /
• 1987

A novel temperature difference-to-frequency converter using two resistance temperature detectors (RTDs) has been developed. The resistance difference of two RTDs is converted into its equivalent inductance to form the resonant circuit of the Colpitts oscillator. The conversion sensitivity of $16\;Hz/^{\circ}C$ and the residual nonlinearity less than 2.15% over the temperature difference range from $35^{\circ}C$ to $155^{\circ}C$ are obtained by the prototype converter. The frequency drift of oscillator itself is ${\pm}0.5\;Hz$. Thus, the minimum detectable temperature difference is estimated to be ${\pm}0.013^{\circ}C$. The proposed converter, except for two RTDs, can be fabricated in monolithic IC form.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.25 no.11
• /
• pp.1282-1285
• /
• 1988

A novel temperature difference-to-frequency converter using two resistance temperature detectors (RTD) has been developed. The resistance difference of two RTD is converted into its equivalent inductance to form the resonant circuit of the Colpitts oscillator. The conversion sensitivity of 16 Hz/$^{\circ}C$ and the residual nonlinearity less than 2.15% over the temperature difference range from 35$^{\circ}C$ to 155$^{\circ}C$ are obtained by the prototype converter. The frequency drift of oscillator itself is $\pm$ 0.5Hz. Thus, the minimum detectable temperature difference is estimated to be $\pm$ 0.013$^{\circ}C$. The proposed coverter, except for two RTD, can be fabricated in monolithic IC form.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.05c
• /
• pp.55-58
• /
• 2001

In this paper, we present the results of the design and fabrication of the VCO(Voltage controlled Oscillator) using RF circuit simulator GENESYS and electromagnetic field simulator EMpower Frequency range is fabricated VCO is 850 MHz ~ 950 MHz, which is used Colpitts Circuit. the fabricated VCO is consisted of resonator, oscillator and MSL(Microstrip Line) is used in LC tuning circuit.(operated by negative feedback) MSL(Microstrip Line), Varactor(Plastic package), low noise TR(SOT-23), chip inductor(1608), chip capacitor(1005), chip resistance(1005). 1005 type is used for sample fabrication of VCO. In the fabrication process, circuit pattern is screen printed on the alumina substrates of over 99.9% purity. Center frequency of the sample VCO is 850MHz at $V_T=1.5V$, while the simulated value was 1.0GHz at $V_T=1.5V$. Variable frequency range of the sample is 860~950MHz in contrast to the 1068~1100MHz of the simulated values.