Showing papers on "Crystal oven published in 2014"

17.8 A 190nW 33kHz RC oscillator with ±0.21% temperature stability and 4ppm long-term stability

Abstract: In wireless networks with a low duty cycle, the radio is operational for only a small percentage of the time. A sleep timer is used to synchronize the data transmission and reception. The total system power is then limited by the sleep power and the sleep timer frequency stability. Low-frequency crystal oscillators are a common choice for sleep timers due to their excellent long-term stability, frequency stability over temperature, and very low power consumption. However, the external crystal cost and board area are undesired. If an integrated oscillator is used as an alternative, the frequency variation must be minimized so the sleep time can be maximized.

Temperature-compensated capacitance–frequency converter with high resolution

Abstract: This article introduces a new method for temperature-compensated capacitance–frequency converter with a single quartz crystal oscillating in the switching oscillating circuit. The novelty of this method lies in the use of additionally connected capacitances in series with JFET switching transistors to the shunt capacitance of the quartz crystal bringing a considerable reduction of the temperature influence of AT-cut crystal frequency change in the temperature range between 0 and 50 °C. The oscillator switching method and parallel switching stray capacitances connected to the quartz crystal do not only compensate crystal's natural temperature characteristics but also any other influences on the crystal such as aging of both the crystal and other oscillating circuit elements. In addition, they also reduce the output frequency measurement error. The experimental results show that through high temperature compensation improvement of the quartz crystal characteristics, this switching method enables 20 zF resolution capacitance to frequency transduction in the range 0–4 pF to 2–45 kHz.

Atomic fountain clock with very high frequency stability employing a pulse-tube-cryocooled sapphire oscillator.

Abstract: The frequency stability of an atomic fountain clock was significantly improved by employing an ultra-stable local oscillator and increasing the number of atoms detected after the Ramsey interrogation, resulting in a measured Allan deviation of 8.3 × 10(-14)τ(-1/2)). A cryogenic sapphire oscillator using an ultra-low-vibration pulse-tube cryocooler and cryostat, without the need for refilling with liquid helium, was applied as a local oscillator and a frequency reference. High atom number was achieved by the high power of the cooling laser beams and optical pumping to the Zeeman sublevel m(F) = 0 employed for a frequency measurement, although vapor-loaded optical molasses with the simple (001) configuration was used for the atomic fountain clock. The resulting stability is not limited by the Dick effect as it is when a BVA quartz oscillator is used as the local oscillator. The stability reached the quantum projection noise limit to within 11%. Using a combination of a cryocooled sapphire oscillator and techniques to enhance the atom number, the frequency stability of any atomic fountain clock, already established as primary frequency standard, may be improved without opening its vacuum chamber.

High Resolution Switching Mode Inductance-to-Frequency Converter with Temperature Compensation

Abstract: This article proposes a novel method for the temperature-compensated inductance-to-frequency converter with a single quartz crystal oscillating in the switching oscillating circuit to achieve better temperature stability of the converter. The novelty of this method lies in the switching-mode converter, the use of additionally connected impedances in parallel to the shunt capacitances of the quartz crystal, and two inductances in series to the quartz crystal. This brings a considerable reduction of the temperature influence of AT-cut crystal frequency change in the temperature range between 10 and 40 °C. The oscillator switching method and the switching impedances connected to the quartz crystal do not only compensate for the crystal's natural temperature characteristics but also any other influences on the crystal such as ageing as well as from other oscillating circuit elements. In addition, the method also improves frequency sensitivity in inductance measurements. The experimental results show that through high temperature compensation improvement of the quartz crystal characteristics, this switching method theoretically enables a 2 pH resolution. It converts inductance to frequency in the range of 85-100 µH to 2-560 kHz.

12.9 A 1.55×0.85mm 2 3ppm 1.0μA 32.768kHz MEMS-based oscillator

Abstract: Mobile time-keeping applications require small form-factor, tight frequency stability, and micro-power 32.768kHz clock references. Today's 32kHz quartz resonators and oscillators are facing challenges in size reduction. Previously described MEMS-based oscillators can achieve tight accuracy but operate at high frequency with power unsuitable for mobile applications. This paper introduces a 32kHz MEMS-based oscillator. Based on a comparison table of recent oscillators shown in Fig. 12.9.6, it offers the smallest size, 1.55×0.85mm2, with the best frequency stability, 100ppm (XO) and 3ppm (TCXO) over the industrial temperature range of -40 to 85°C. Supply current is 0.9 and 1.0μA for XO and TCXO, respectively, at supply voltages from 1.5 to 3.6V.

High-performance DSP-TCXO using twin-crystal oscillator

Abstract: This paper describes a summary of the high stability DSP-TCXO (Digital Signal Processing-Temperature Compensated Crystal Oscillator) based on a high-accuracy temperature detection technology using two AT-cut crystal oscillators and a high-precision frequency compensation circuit.

Method of switching guest-host dual frequency liquid crystal by using back flow

Abstract: Provided are methods of switching guest-host dual frequency liquid crystals by using a back flow. In the case of a shutter having a dual frequency liquid crystal layer between two transparent substrates, such a method includes: applying a first voltage having a first frequency to the dual frequency liquid crystal layer; and applying a second voltage having a second frequency to the dual frequency liquid crystal, the second frequency being higher than the first frequency, wherein the second voltage is higher than a threshold voltage that generates a back flow around liquid crystals of the dual frequency liquid crystal layer, and the first voltage is lower than the threshold voltage.

Dual-mode crystal oscillator

Abstract: A dual-mode crystal oscillator includes a single AT-cut quartz crystal piece, a package, and an integrated circuit. The integrated circuit includes an oscillation circuit configured to cause the AT-cut quartz crystal piece to oscillate at a frequency in the MHz band, a dividing circuit configured to divide the frequency in the MHz band to generate a frequency of 32.768 kHz, a selection circuit configured to select one of a pause state where the frequency in the MHz band is not output and an active state where the frequency in the MHz band is output. The mounting surface includes three electrodes arranged in a direction along the long side and two electrodes arranged in a direction along the short side. The electrode to output the frequency of 32.768 kHz and the electrode to output the frequency in the MHz band are arranged not adjacent to one another.

A new small-sized pierce crystal oscillator readout with novel on-chip all-digital temperature sensing and compensation

Abstract: This paper presents a 16-MHz digital-controlled crystal oscillator and a time-domain temperature sensor design to achieve a high precision temperature-compensated crystal oscillator in a low-power mobile device. The digital-controlled crystal oscillator is based on Pierce topology with two 8-bit switched-capacitor arrays and the temperature of it is measured by time-domain temperature sensor. For noise reduction, the supply voltages of digital-controlled crystal oscillator and time-domain temperature sensor are regulated at 1.2 V by using two on-chip low-dropout regulators. The proposed circuit design has been successfully fabricated by using TSMC 0.18-μm CMOS process, where the active area is 0.516 mm2. The measured startup time of fabricated 8-bit digital-controlled crystal oscillator is about 0.35 ms and the measured phase noise of 1 kHz offset at 25°C is -119.93 dB/Hz. With temperature compensation, the frequency deviation of it is within +/- 0.08 ppm over -40°C to 85°C. The measured effective temperature resolution of time-domain temperature sensor is 0.45 °C/LSB and the measured error is within -6.3°C to 7.1°C at 10 Hz conversion rate. The measured current consumption of chip is about 2 mA.

Crystal oscillator start-up circuit

Abstract: A crystal oscillator start-up circuit capable of reducing a start-up time of a crystal oscillator is disclosed. The crystal oscillator start-up circuit is provided with a crystal oscillation unit including a crystal oscillator, a converter and an external oscillator. The crystal oscillation unit generates an output signal corresponding to the impedance characteristic of the crystal oscillator. The converter converts the output signal of the crystal oscillation unit to a voltage signal. The external oscillator outputs to the crystal oscillation unit an oscillation signal whose frequency is adjusted by the voltage signal to approach a resonance frequency of the crystal oscillator.

Precise beat frequency evaluation circuit for multi-oscillators QCM gas detectors

Abstract: Presented work deals with crystal oscillators that can be used as a quartz crystal microbalance (QCM) gas sensor. There are presented two basic oscillators that are very common in literature. The oscillators were put into practice and tested in the gas chamber with different crystals of basic frequency 10 MHz. There were tested clean crystal resonators and resonators coated by a sensitive layer. Frequency response of the oscillators is usually very small and it is comparable with the effects such as temperature change or crosstalk in the evaluation circuit. The evaluation circuit thus must be designed carefully. Main goal of this paper is comparison of two basic designs of the oscillators and presentation of the precise evaluation circuit with minimal crosstalk and reverse transmission in signal ways.

Nonlinear model of crystal resonator and its application to phase noise simulation of oscillator

Abstract: AT-cut quartz crystal resonators are widely used in communication equipment, measurement instruments, computers and etc. The resonance frequency of AT-cut crystal resonator changes proportional to the square of its driving current. The frequency drive level dependency can be modeled by introducing nonlinearity in the equivalent series capacitance of a crystal resonator. We have determined the nonlinear parameter of a 26MHz crystal resonator from the measured data and simulated its frequency drive level dependency. The simulated results agreed well with the measured frequency drive level dependency. And we simulated the phase noise of a CMOS inverter crystal oscillator using the nonlinear model. We found the increase of phase noise of oscillator in the f -2 region.

A UHF SiGe push-pull quartz MEMS oscillator

Abstract: Compact oscillators at UHF frequencies and below are challenging for IC designers because of the large size of the passive components, particularly the inductors. An integrated SiGe push-pull sustaining circuit fabricated in the IBM 7WL process eliminates the need for inductors. Combining this circuit with and an external quartz resonator allowed the development of 708 MHz and 744 MHz fundamental mode oscillators. The lowest phase noise achieved was -103 dBc/Hz at a 1 kHz offset for the 708 MHz oscillator. Oscillator total power consumption is <;20 mW.

Crystal controlled oscillator

Abstract: A crystal controlled oscillator includes a crystal unit, an oscillator circuit, a temperature detector for crystal unit, a heating unit for crystal unit, a temperature detector for oscillator circuit, and a heating unit for oscillator circuit. The heating unit for crystal unit is configured to control an output of the crystal unit based on a temperature detected by the temperature detector for crystal unit to compensate the temperature of the atmosphere where the crystal unit is placed to be constant. An output of the heating unit for oscillator circuit is controlled independently from the heating unit for crystal unit based on a temperature detected by the temperature detector for oscillator circuit to compensate the temperature of the atmosphere where the oscillator circuit is placed to be constant.

Driving crystal oscillator startup at above, below and operating frequency

Abstract: A circuit includes a crystal oscillator to generate an output frequency for a circuit. A driving oscillator generates a startup signal having a driving frequency that is provided to activate the crystal oscillator. The driving frequency of the startup signal is varied over a range of frequencies that encompass the operating frequency of the crystal oscillator to facilitate startup of the crystal oscillator.

OPTICAL PARAMETRIC OSCILLATOR AND SECOND HARMONIC GENERATOR USING MONOCLINIC PHASE Ga2S3 CRYSTAL

Abstract: This disclosure provides a second harmonic generator and an optical parametric oscillator, the second harmonic generator and the optical parametric oscillator comprise one or more nonlinear optical frequency conversion crystal and a pump laser source, the nonlinear optical frequency conversion crystal is a monoclinic Ga.sub.2S.sub.3 crystal, the space group of the monoclinic Ga.sub.2S.sub.3 crystal is Cc, and the unit cell parameters are a=11.1.ANG., b=6.4.ANG., c=7.0.ANG., .alpha.=90.degree., .beta.=121.degree., .gamma.=90.degree., and Z=4.

Crystal controlled oscillator and oscillating device

Abstract: A crystal controlled oscillator of the present disclosure includes: an oscillator circuit for oscillator output, a first oscillator circuit, a second oscillator circuit, a heating unit, a pulse generator, a frequency difference detector, an addition unit, a circuit unit, a frequency measuring unit, a determination unit, and a signal selector. The signal selector is configured to: select a control signal where electric power supplied to the heating unit is smaller than supplied electric power in the detection range in a case where a frequency in a set period at the train of pulses is out of the detection range at the high temperature side; select a control signal where electric power supplied to the heating unit becomes a preset value in a case where a frequency in the set period at the train of pulses is out of the detection range at the low temperature side.

Oven controlled crystal oscillator

Abstract: An oven controlled crystal oscillator (OCXO) is provided for improving temperature characteristics of a frequency. In the OCXO, a thermostatic oven 5 ( 20 a ) is provided in a thermostatic oven 9 ( 20 b ), a temperature control circuit 13 controls a temperature in the thermostatic oven 9 based on a temperature detected by a temperature sensing element 10, a first resonator 1 and a second resonator 2 are provided in the thermostatic oven 5, a temperature control circuit 8 controls the temperature based on an oscillation frequency difference between the two resonators, and especially, the temperature control circuit 13 controls the temperature to be within the temperature region where the oscillation frequency difference between the first resonator 1 and the second resonator 2 corresponds with the resonator temperature in a one-to-one manner, and the temperature gradient is either in a positive direction or in a negative direction.

Method and device for adjusting carrier frequency of multiple-input multiple output microwave device

Abstract: The present invention provides a method and a device for adjusting a carrier frequency of a multiple-input multiple-output microwave device. The method includes: obtaining, by an indoor unit IDU, a frequency of a radio frequency-reference crystal oscillator and a first frequency multiplication factor of each outdoor unit ODU; selecting, by the indoor unit IDU, one of the frequencies of the radio frequency-reference crystal oscillator as a reference frequency; adjusting, by the indoor unit IDU, a carrier frequency of the multiple-input multiple-output microwave device according to the first frequency multiplication factor and a radio frequency offset between the reference frequency and the frequency of the radio frequency-reference crystal oscillator of each ODU.

Recent achievements in performance of 100 MHz crystals and OCXOs

Abstract: In recent years low noisy precision 100 MHz oscillators for continuous operation up to 15 years became more and more important for modern telecommunication and measurement equipment. Often it is important to minimize both close-in phase noise (at 10, 100 and 1000 Hz from carrier) and noise floor (at 10, 100 and 1000 kHz from carrier). Requirements became tougher not only for phase noises and various kinds of frequency stabilities, but also for OCXOs' reliability. To meet modern requirements for 100 MHz precision quartz oscillators, it is necessary to undertake actions targeted for improvement of reliability, optimization of both design and electronics of oscillator and considerable improvement of performance of quartz crystal. Successful advancement in these directions was made by authors in Morion Inc. during Y 2013.

Note: Sensitivity multiplication module for quartz crystal microbalance applications

Abstract: In this Note, a novel sensitivity multiplication module was added to classical quartz crystal microbalance (QCM). The purpose is to increase QCM frequency shift without changing nominal frequency of the quartz crystal resonator or nominal frequency value delivered to the frequency counter. Allan deviance measurement confirms that the multiplication of the frequency shift is limited by the quartz crystal loads with direct effect in quartz crystal quality factor and oscillator stability. An experimental implementation of this new sensitivity multiplication module that can increase up to six times the frequency shift of the QCM was experimentally investigated using different load conditions.

Digitally controlled thermostat for a high-stable crystal oscillator

Abstract: In this paper, we describe the hardware and software designing process and characterization for an original digitally controlled double thermostat system for the quartz crystal oscillator. This allows setting the turnover point of crystal oscillators automatically. Developed for metrological purposes of active phase noise measurements, this type of thermostat with a crystal oscillator is an ultra-stable DOCXO oscillators.

Susceptibility of the Crystal Oscillator to Sinusoidal Signals over Wide Radio Frequency Range

Abstract: Oscillators are sensitive to radio frequency interference. Therefore they can be applied to measure radio frequency interference. Radio frequency interference sources cover wide frequency ranges. It is interesting to see the frequency dependence of the oscillator susceptibility to radio frequency interference. This paper uses the crystal oscillator as the device under test and performs a systematic simulation on susceptibility. The transistor-level simulation shows that the oscillator susceptibility varies strongly with the signal frequency. The behavior of the oscillator susceptibility could be characterized with critical features and explained with three response modes. Both the simulated behavior and the proposed response mechanism are confirmed with the measurement results. The conclusion of the paper helps to calibrate oscillator sensors. It is also an important guideline for building analysis model in the design phase of the sensor. Copyright © 2014 IFSA Publishing, S. L.

Tuning fork type quartz crystal oscillator resonant frequency measurement method based on sound excitation and device

Abstract: The invention relates to a tuning fork type quartz crystal oscillator resonant frequency measurement technology, in particular to a tuning fork type quartz crystal oscillator resonant frequency measurement method based on sound excitation and a device. The technical problem that the outside electromagnetic environment and measurement spaces easily limit measurement and accordingly enables a result to be inaccurate when inherent frequency of an existing tuning fork type quartz crystal oscillator is measured is solved. The tuning fork type quartz crystal oscillator resonant frequency measurement method based on sound excitation comprises the following steps of (a) adopting laser beams to perform excitation on the tuning fork type quartz crystal oscillator to be measured; (b) introducing a probe beam while scanning the sound wave frequency; (c) acquiring reflection light intensity change information received by one receiving face fixed at a spatial position and converting the intensity change into a corresponding electrical signal; (d) demodulating the electrical signal of reflection light and obtaining the inherent frequency of the tuning fork type quartz crystal oscillator to be measured according to a frequency response curve. By adopting the tuning fork type quartz crystal oscillator resonant frequency measurement method based on the sound excitation, electromagnetic signal interference is effectively avoided, and the probe problem in a narrow space is solved.

Highly-stable metrological thermostat for active characterization of resonators with automatic turnover point settings

Abstract: In this paper, we describe an original digitally controlled double thermostat system for the quartz crystal oscillator that allows setting the turnover point of crystal oscillator automatically and its characterization. The oscillator optimization was implemented with ADS software. This simulation included the resonator noise and amplifier noise, which was measured previously for different transistors.

Suppressing the frequency jump in quartz crystal microbalance

Abstract: Quartz crystal microbalance (QCM) acquires the mass information through measuring the frequency shift. The detection sensitivity can achieve to nano-gram. A type of 15MHz QCM used in space contamination detection appeared the frequency jump when switching the power supply repeatedly, which disabled the measurement function. The analysis was made from quartz resonator and oscillator circuit which deciding the QCM's frequency, and the conclusion was drawn that properly designing the resonator electrodes and the oscillator circuit parameters could suppress the frequency jump. The suppressing methods were carried out on the 15MHz quartz crystal microbalance (QCM), and effectively controlled the frequency jump. Trying the power supply switching test 200 times, the frequency jump didn't appear any more. At the end, a simple method to verify the suppressing effect is provided.

Matched crystal filters

Abstract: Crystal oscillators and filters are still very important devices in modern telecommunication and measurement equipment. Quartz crystal units are basic elements for those oscillators and filters, due to their extremely stable resonant frequency and Q-factor. Matched crystal filters are consisted of filter sections with the same phase characteristics. In this paper the design and realization of a new type of matched filters with quartz crystal units is described.

Device and method for adjusting an oscillation frequency of a VCTCXO oscillator

Abstract: The invention relates to a device (110) which comprises a temperature sensor (111) and accesses an external time or frequency reference (121; 130) in order to retime an oscillation frequency of a VCTCXO oscillator (113). The device determines a variation in the ambient temperature of the VCTCXO oscillator over a time range that is predetermined using measurements from the temperature sensor, and adjusts a frequency or a rate of access to the external time or frequency reference in order to obtain time or frequency information for retiming the oscillation frequency of the VCTCXO oscillator depending on the temperature variation determined.

Method for sensing crystal oscillator frequency shift

Abstract: The invention discloses a method for sensing crystal oscillator frequency shift. The method comprises the steps of measuring static phase noise of a crystal oscillator in a static state; setting vibration environment conditions, performing multiple metering on the crystal oscillator vibrating under the vibration environment conditions, obtaining a plurality of groups of vibration phase noise; performing difference calculation on each group of vibration phase noise and the static phase noise, obtaining a plurality of groups of frequency shift values; performing screening processing on each group of frequency shift values so as to remove frequency shift values larger than a preset threshold; obtaining each group of remaining frequency shift values, correcting fitting functions corresponding to a last group of frequency shift values according to a preset response surface model and each group of frequency shift values, obtaining a final fitting function, and determining the acceleration sensitivity direction of the final fitting function. The method can improve accuracy of crystal oscillator frequency shift sensing, and accordingly an influence mechanism influencing crystal oscillator electrical property under the vibration environment conditions is excavated.