Showing papers on "Crystal oven published in 2012"

Compensation for crystal frequency using multiple temperatures

Abstract: A method in a mobile communication device includes: measuring a first temperature associated with a crystal configured to provide a reference signal having a frequency; measuring a second temperature associated with a component that is coupled to the crystal by an electrically and thermally conductive line; and compensating, based upon the measuring of the first and second temperatures, for a change in the frequency of the reference signal of the crystal.

Temperature Compensation of Aluminum Nitride Lamb Wave Resonators Utilizing the Lowest-Order Symmetric Mode

Abstract: : Frequency references with a low phase noise and a low temperature-induced frequency drift are important components for navigation systems, wireless communication systems, and signal processing applications. As is well known, crystal oscillators (XOs) and temperature compensated crystal oscillators (TCXOs) based on AT-cut quartz dominate this market because AT-cut quartz has outstanding frequency-temperature performance and long-term stability. However, there are drawbacks and fabrication limitations for quartz-based resonators related to down-scaling for future applications. In addition, the material properties of quartz limit the integration of the frequency references and the complementary metal-oxide semiconductor (CMOS) circuits on a single chip. As a result, there has been a great interest in the realization of low-cost, CMOS-compatible, high quality factor (Q), and temperature-stable micro-electro-mechanical systems (MEMS) resonators.

Method and apparatus of a crystal oscillator with a noiseless and amplitude based start up control loop

Abstract: A large gain is used to start up the oscillation of the crystal quickly. Once the oscillation starts, the amplitude is detected. A control circuit determines based on the measured amplitude to disable a low resistance path in the controlled switch array to reduce the applied gain below the power dissipation specification of the crystal. Another technique introduces a mixed-signal controlled power supply multi-path resistive array which tailors the maximum current to the crystal. A successive approximation register converts the amplitude into several partitions and enables/disables one of several power routing paths to the inverter of the oscillator. This allows a better match between the crystal selected by the customer and the on-chip drive circuitry to power up the oscillator without stressing the crystal. The “l/f” noise of the oscillator circuit is minimized by operating transistors in the triode region instead of the linear region.

Gas sensing using thermally actuated dual plate resonators and self-sustained oscillators

Abstract: This paper presents an experimental investigation of the characteristics of dual plate thermal-piezoresistive MEMS resonators and self-sustained oscillators in different gases. It has been demonstrated that the natural frequency of such devices changes in different gases. Interestingly, for the same silicon structure, frequency shifts in opposite directions were observed when operated in a resonator versus a self-sustained oscillator configuration. Both thermal conductivity and density of the surrounding gas have been identified as factors affecting the operating frequency of such devices. It has been demonstrated that in resonator configuration (linear operation), the resonator frequency shift is mostly a function of gas thermal conductivity. In the oscillator configuration (nonlinear operation) however, the effect of gas density on the nonlinear stiffness of the oscillator is the dominant factor. Relatively large measured frequency shift, as high as −1340ppm in a 1:5 mixture of helium-nitrogen compared to the natural frequency in pure nitrogen, shows the potential of such devices as highly sensitive gas sensors.

Temperature compensation of crystal oscillators using an Artificial Neural Network

Abstract: Temperature Compensated Crystal Oscillators (TCXOs) are widely used and well known frequency control products. Their performance has improved over the decades with the advent of newer and improved technologies. Evolution of the TCXO from resistor thermistor networks to modern polynomial generators has pushed TCXO temperature stabilities to nearly +/−100ppb deviation over the industrial temperature range of −40 to +85 °C. Even with these great advances, users always need tighter stabilities. This paper focuses on a new temperature compensation technique for crystal oscillators. Through the use of an Artificial Neural Network (ANN), temperature compensation of AT cut crystal oscillators can be achieved with better than +/−10ppb stability over the industrial temperature range (−40 to +85 °C). This is more than a 10 fold improvement over state of the art polynomial function generator compensation. The theory of this compensation method will be discussed, and data showing the results of temperature compensation on actual oscillators will be presented.

Temperature compensation of a quartz tuning-fork clock crystal via post-processing

Abstract: The dependence of a tuning-fork quartz crystal oscillator's frequency f on temperature T is observed over the temperature range −5 to 20°C. From this, a parabolic f(T) function is fit to the crystal's data, and used to compensate for sampling period drift in an Analog to Digital Converter (ADC) system based around this crystal at various temperatures. Resolution and uncertainty of this method are discussed.

Techniques minimize the phase noise in crystal oscillator circuits

Abstract: This paper reports a methodology of combining differential-phase-shift-injection-locking (DPSIL) with mode-coupled-delay-feedback (MCDF) techniques to shave the size, cost, and phase noise from Crystal oscillator circuits. An example of 100 MHz, 125 MHz and 155 MHz ovenized crystal oscillator (OCXO) is demonstrated for the validation of the novel approach, which holds good for both fundamental and higher order overtone mode high frequency crystal oscillator circuits.

Crystal Oscillator Design

Abstract: Crystal oscillators are commonly used as reference frequency standards for synthesis of the harmonic signal required for their operation in synthesizer and timing devices. The phase noise of these reference frequency standards limits the noise floor and electromagnetic interference susceptibility that affects the dynamic range, selectivity, and sensitivity of a receiver. This contribution is devoted to design guidelines for selecting the low-phase-noise topology of crystal oscillator circuits for the applications in modern communication systems. Numerous practical examples are demonstrated and validated with computer-assisted design (CAD) simulation and measured results, which allows for the realization of high-performance stable reference frequency standards. Keywords: crystal oscillator; crystal resonator; drive level; EMI; output power; mode-coupling; phase noise; FOM; sensitivity; Q-factor; noise model

Voltage-controlled narrowband and wide, variable-range four-segment quartz crystal oscillator

Abstract: In this work, our goal is to develop a voltage-controlled variable-frequency quartz crystal oscillator with narrowband response, wide, variable frequency range and the capacity to oscillate across the series resonance frequency using a four-segment configuration of a quartz crystal oscillator. In conventional quartz oscillators, the quartz resonator is inserted in the feedback loop between the input and the output of the active circuit, providing sufficient gain and the phase relation. In the oscillator developed here, the quartz crystal resonator is inserted between the loop circuit and the ground potential. The performance of the voltage-controlled variable-frequency oscillator is demonstrated across the series resonance frequency.

Noise Measurement Setup for Quartz Crystal Microbalance

Abstract: Quartz crystal microbalance (QCM) is a high sensitive chemical sensor which has found widespread spectrum of applications. There are several mechanisms that are related to fluctuation phenomena. Since the aim of our research is oriented to study the sensitivity and influ- ence of different kind of noises on sensor resolution, we modified an existing method to measure the small fre- quency fluctuation of QCM. The paper describes our measurement setup, in which a quartz crystal oscillator with coated active layers and a reference quartz oscillator are driven by two oscillator circuits. Each one regulates a frequency of a crystal at the minimum impedance which corresponds to the series resonance. A data-acquisition card triggers on the rise-edges of the output signal and stores these corresponding times on which the instantane- ous frequency is estimated by own-written software. In comparison to other measurement setups, our approach can acquire immediate change of QCM frequency, thus, chemical processes can be even described on the basis of high-order statistics. The experiments were provided on quartz crystals with the sorption layer of polypyrrole, which is suitable for the construction of QCM humidity sensors.

Timepiece device and method of operation thereof

Abstract: The invention relates to a timepiece device (1), in particular for a vehicle, comprising a control unit (2) for time keeping, which is synchronizable by a clock generator. Thereby the timepiece device (1) having at least two crystal oscillators built respectively by at least one crystal unit (3.1, 3.2), whereby a first crystal oscillator with a first crystal unit (3.1) and with a predetermined nominal oscillation frequency is suitable for use as the clock generator of the control unit (2) during a vehicle standby mode, and whereby the oscillation frequency of the first crystal oscillator is at least temporarily measured and adjustable by a second crystal oscillator with a second crystal unit (3.2) whose nominal oscillation frequency is higher than that of the first crystal oscillator. Further the invention relates to a method of operation of the timepiece device (1), whereby the oscillation frequency of the second crystal oscillator is compensated against the temperature by the software inside the control unit (2).

Wellbore Instrument Clock Oscillator and Instrument System Made Therewith

Abstract: A clock oscillator includes a first crystal controlled oscillator, a second crystal controlled oscillator and a logic controller functionally coupled to the first and second crystal controlled oscillators. The logic controller is programmed to calculate a frequency of the first crystal controlled oscillator as a function of the frequency of the first crystal controlled oscillator with respect to a frequency of the second crystal controlled oscillator characterized with respect to an environmental parameter.

Method for determining design values for crystal oscillator circuit and electronic apparatus

Abstract: According to the invention, two of three design values, i.e., the negative resistance RL, load capacitance CL and drive current Ios of a crystal oscillator circuit including a crystal resonator are determined to determine the remaining one design value from a relation equation or relation graph. As a result, reducing the CL of the crystal oscillator circuit allows the drive current Ios to be reduced, achieving reduced power consumption of the crystal oscillator circuit.

The Acceleration Effects on Crystal Oscillators and Research on Compensating Technique

Abstract: As the reference frequency source,crystal oscillator plays a critical role in the electronic equipments.Crystal oscillator is sensitive to the acceleration,such as vibration,concussion and centrifugal force,which would influence the stability of the frequency output.How acceleration affects the frequency and phase noise of crystal oscillator is discussed,some current measures of reducing the acceleration effects are introduced.A new method based on the digital compensating system is also brought up.

Heating device of continuous polysilicon purifying crystal oven

Abstract: The invention relates to a heating device of a continuous polysilicon purifying crystal oven The device comprises a combined heating device, a temperature sensor and a temperature control meter; the combined heating device is combined by heating elements on the laterals, top, upper parts of the laterals and low parts of the laterals of a hearth; and multistage in the length direction and temperature ranges in the height direction can be controlled through compound control under different powers so as to realize continuous unidirectional solidification The combined heating device is composed of an upper auxiliary heating element group and a lateral heating element group, wherein the upper auxiliary heating element group and the lateral heating element group are heating element groups any of which is composed of a plurality of heating elements so as to realize the temperature gradient demand desired by the product unidirectional solidification; the temperature of the upper temperature range is set to be 1436-1420 DEG C and the temperature of the upper temperature range is gradually reduced in upward direction of crystallization interface and with the time of crystallization so as to realize multistage and multiple temperature ranges control The unidirectional solidification can be realized in the continuous oven with the heating device of the invention so as to benefit the improvement of polysilicon purification qualification rate and the reduction of cost, thus having great significance

Crystal oscillator with dual amplitude stabilization feedback loop

Abstract: In this paper crystal oscillator realized in 90 nm Low Leakage UMC CMOS technology is presented. It is based on the Pierce architecture and uses dual feedback loop to limit the amplitude and generate bias point. Dual feedback architecture allows to achieve almost rail to rail signal with low harmonic levels for wide range of supply voltage. Both of those features have positive impact on phase noise level. The oscillator was designed to work with 16 MHz crystal. It can work with supply voltages from 0.6 to 1.8 V and consumes 78.4µA for 1.2 V supply. In typical case phase noise for 1.2 V supply voltage is −160 dBc/Hz at 10 kHz offset.

A new generation DSP-OCXO using crystal temperature sensor

Abstract: This paper reports on a development and tests of the DSP-OCXO (Digital Signal Processing-Oven Controlled Crystal Oscillator) using AT cut crystal high accuracy temperature sensor which consisting of two thermal equivalent crystals. For the applications of the small size base stations, the DSP-OCXO which has following features: 14 × 9 mm small size, 0.6 W maximum at +25°C low power consumption and +/−20 ppb maximum /−40 to +85°C high frequency stability vs. temperature has been developed.

Recent achievements in performance of low profile ultra precision single oven quartz oscillators

Abstract: The article gives a description of single oven-controlled quartz oscillators (OCXO), which frequency stability comparable with double oven-controlled quartz oscillators (DOCXO), and are considerably lower in weight, consume less power, and are smaller in sizes (up to a height thereof to 10 mm).

Dual frequency crystal oscillator

Abstract: An oscillator is disclosed comprising a first crystal operable to generate a first oscillating signal at a first frequency, and a second crystal coupled to the first crystal and operable to generate a second oscillating signal at a second frequency higher than the first frequency. The oscillator further comprises a DC restore circuit operable to generate a third oscillating signal comprising a substantially fifty percent duty cycle in response to the second oscillating signal.

PSPICE simulation of quartz crystal oscillation circuit based on CMOS inverter

Abstract: Quartz crystal oscillator is very commonly used in electronic devicesIn the circuit design and the teaching,the simulation analysis of quartz crystal oscillator circuit is often neededA method of using the PSpice simulation software to simulate quartz crystal oscillation circuit is introduced by instanceAccording to the equivalent circuit of quartz crystal oscillator,the series and parallel resonant frequency of quartz crystal was analyzed,quartz crystal simulation model was,the vibration waveform and amplitude waveform were observed,and its oscillation frequency in the emulator was testedBased on the of different element parameters,sweeping analysis of the oscillator was conducted

Acceleration Effect and Sensitivity Measurement of the Quartz

Abstract: Quartz crystal oscillator is used as the standard frequency source or pulse signal source to provide frequency benchmark because of its stable output frequency.It cannot be substituted by any other kinds of oscillators.But the problem how to compensate the influence of acceleration on the output frequency of the quartz crystal oscillator has not been worked out.The acceleration has become the important factor affecting the quartz crystal oscillator precision.This paper introduces the influence of acceleration on the oscillator frequency and the methods for measuring the acceleration sensitivity.Also,some experiments were performed to verify the effect of the digital compensation.

Realization of ultra-high quality factor of dual-T quartz crystal resonator circuit

Abstract: In this paper, we have shown the method to obtain the ultra-high quality factor of a dual-T crystal resonator circuit. In this circuit, the phase shifters are inserted in each T circuit of the dual-T crystal resonator circuit. We have made the simulation and measurement of the proposed dual-T crystal circuit. The attained effective Q is about three times bigger than the unloaded Q of a crystal resonator (about 140,000). And we have made the oscillator using this dual-T circuit and made the simulation of phase noise. 30 through 60 dB improvement of phase noise is suggested in 1/f offset frequency region. The measurement shows the comparable phase noise improvement.

Sequenced mode TCXO

Abstract: TCXO's first became available in the early 1960's. The accuracy was limited to about 0.5 ppm by the degree to which the analog thermistor networks could track the crystal temperature curve. The advent of digital compensation eliminated the curve fitting problem, but accuracy was still limited to about 0.1 ppm due to retrace problems in the oscillator. Making the oscillator pullable also made it less stable. The effect was reduced by synthesizing the output frequency in some way rather than pulling the crystal to frequency. This also allowed the use of SC-cut crystals and improved the accuracy to a few parts in 108. Dual mode temperature sensing improved thermal tracking, but hysteresis effects in the crystal still limited the accuracy. Implementation of a dual mode oscillator presents some challenges that, depending on the circuit, may result in additional hysteresis being introduced by circuit elements.

New design of high-precision oven controlled crystal oscillator

Abstract: Combining oven controlled technique,digital compensation,high-resolution frequency difference measurement and self-calibration technique,a new design method of precise oven controlled crystal oscillator(OCXO) is proposed.Fine compensation is made in the vicinity of the crystal temperature inflection point by using the non-real-time temperature compensation strategy,and self-calibration system is integrated in the crystal.The method improves the digital compensated phase noise,simplifies the traditional OCXO development system,reduces the cost and shortens the developing cycle.Experiment results show that with a standard reference signal and self-calibration updated data,the oscillator can work stable and achieve its best performence.The performance index of crystal oscillator had an improvement with one to two orders of magnitude on the basis of original technical index.The method is widely used in the improvement of high-end crystal oscillator and atomic clock.

Voltage-controlled double-resonance quartz oscillator using variable-capacitance diode

Abstract: In this work, we present a variable-frequency quartz crystal oscillator that is able to oscillate at LC resonance under frequency locking of a quartz crystal resonance, with the frequency tuning realized by variable-capacitance diodes. This circuit shows a steep transition between LC oscillation modes to quartz crystal double-resonance, which shows a characteristic change in the oscillation frequency. Control voltage of this diode is precisely adjusted from the low side to higher values and conversely in the vicinity of the oscillation mode transition. The transition of the oscillation modes is experimentally demonstrated and compared with an algebraic analysis.

Oven controlled crystal oscillator and manufacturing method thereof

Abstract: The present invention discloses an Oven Controlled Crystal Oscillator and a manufacturing method thereof. The Oven Controlled Crystal Oscillator comprises a thermostatic bath, a heating device, a PCB and a signal generating element, where the signal generating element is used for generating a signal of a certain frequency, the heating device, the PCB and the signal generating element are mounted in the thermostatic bath, the signal generating element is mounted in a groove formed on one side of the PCB, while the heating device is mounted against the other side of the PCB that is opposite to the groove. The signal generating element may be a passive crystal resonator or an active crystal oscillator. The Oven Controlled Crystal Oscillator according to the invention is advantageous for a small volume and a high temperature control precision.

An initial study on the frequency dependent failure mode of the crystal oscillator under radio frequency interference

Abstract: Based on measurements and simulations, this paper develops three failure modes to describe the radio frequency immunity of the crystal oscillator module of complex integrated circuits. Each failure mode is effective in a certain range of the interference frequency. The definition of the failure modes helps to understand the intrinsic frequency response of the naked circuit modules on the chip. It is an important step to explain and to calculate the complex frequency response of the immunity of the whole complex integrated circuits.

The Design of AT-Cut Multiple-Electrode Quartz Crystal Resonator and the Research of its Oscillation Stability and Force-Frequency Property

Abstract: According to the oscillation characteristics of the quartz crystal resonator and the relationship between its force sensitive property and stress distribution on crystal plate, the single-base multiple-electrode quartz crystal resonator is designed. The oscillation stability of the resonator with this structure is tested by using crystal frequency stability tester. The force-frequency property of the resonators formed by electrodes on different positions of the new structure crystal plate is studied by adding radial force on it. The experimental results show that when the new structure quartz crystal resonator works driven by integrated chip, its oscillation frequency stability can reach 10-8, with the electrode thickness increasing, the oscillation stability of the resonators improves. The force-frequency property of the resonator on the different position of the same crystal plate is different, and the force-frequency coefficient has an obvious difference. The total force-frequency coefficient of the newly designed single-base three-electrode quartz crystal resonator can reach 338.8Hz/N by using mix frequency process.

Quartz oscillator module

Abstract: A quartz oscillator module includes a first quartz oscillator, a second quartz oscillator, a first electronic switch, and a second electronic switch. The first and second quartz oscillators provide two different clock signals. When the first electronic switch is turned on, the first quartz oscillator is activated. When the second electronic switch is turned on, the second quartz oscillator is activated.

A brief view of the current state of the development and aging performance of fixed frequency surface acoustic wave (SAW) Oscillator

Abstract: The recent rapid expansion of optical fiber networking market fuels the demand for accurate 100∼400 MHz fixed frequency oscillators based on surface acoustic wave (SAW) technology. Nowadays, several suppliers can offer small size and cost efficient SMD single-end and differential SAW oscillators (SOs) with very good phase jitter performance. Selective customers prefer SO solution as it is free of the unsettling problems from some crystal oscillator (XO) solutions- high cost of high frequency fundamental (HFF) and inverted mesa (IM) crystal blanks, spurious modes, frequency jumping, drive level sensitivity, high cost of phase lock loop (PLL) die, etc. This paper is to provide a brief view of the current state of the development of fixed frequency SOs. Based on the aging data of more than 20,000 hours at 125°C, the authors also comment on the SO aging performance fabricated using different SAW wave-types.