Showing papers on "Crystal oven published in 2015"

High-Frequency TaO x -Based Compact Oscillators

Abstract: In this paper, we demonstrate three key features of oxide-based nano-oscillators: 1) the observation of threshold switching and filamentary oscillations in TaO x ; 2) the highest frequency achieved by oxide-based oscillators; and 3) a study with linear (resistor) and nonlinear (transistor) ballasts to clearly understand the role of filament dynamics in scaling. These oscillators show frequency tunability over the range of 20 kHz–250 MHz, with 250 MHz being the highest reported frequency for this class of oscillators. Different types of ballasts show frequency tunability using two distinct methods: 1) by tuning the channel resistance of the transistor and 2) by increasing the rail voltage across the ballast–device pair. This sheds new light on the oscillator dynamics for dense oscillator arrays aimed at oscillatory neural networks and other applications.

A Fully Integrated Oven Controlled Microelectromechanical Oscillator—Part II: Characterization and Measurement

Abstract: This paper, the second of two parts, reports the measurement and characterization of a fully integrated oven controlled microelectromechanical oscillator (OCMO). The OCMO takes advantage of high thermal isolation and monolithic integration of both aluminum nitride (AlN) micromechanical resonators and electronic circuitry to thermally stabilize or ovenize all the components that comprise an oscillator. Operation at microscale sizes allows implementation of high thermal resistance platform supports that enable thermal stabilization at very low-power levels when compared with the state-of-the-art oven controlled crystal oscillators. A prototype OCMO has been demonstrated with a measured temperature stability of −1.2 ppb/°C, over the commercial temperature range while using tens of milliwatts of supply power and with a volume of 2.3 mm $^{3}$ (not including the printed circuit board-based thermal control loop). In addition, due to its small thermal time constant, the thermal compensation loop can maintain stability during fast thermal transients (>10 °C/min). This new technology has resulted in a new paradigm in terms of power, size, and warm up time for high thermal stability oscillators. [2015-0036]

100-MHz Low-Phase-Noise Microprocessor Temperature-Compensated Crystal Oscillator

Abstract: An AT-cut third-overtone 100-MHz quartz crystal resonator was used to achieve a 100-MHz low-phase-noise voltage-controlled crystal oscillator prototype. The unloaded quality factor of the used resonator is about 132 K, and the equivalent dynamic capacitance is about 1.2 fF. For the characteristic of the large equivalent dynamic capacitance of the resonator, the design method and the actual measured data of the low-phase-noise oscillator prototype are given. An explanation of why larger equivalent dynamic capacitance and higher voltage-control sensitivity can lead to bad phase noise in half-bandwidth is given. The STM32F103RCT6 MCU is used to read the real-time data of temperature sensor of the microprocessor temperature-compensated crystal oscillator (MTCXO) and the real-time control voltage loading on the MTCXO. Therefore, the real-time communication between a personal computer and an MTCXO is achieved. The control voltage $V$ achieved in this way has already considered both the effect of the actual working condition of the MTCXO circuit and the effect of the MTCXO internal reference voltage that it is not accurate enough. After temperature compensation, the measured temperature performance of the 100-MHz low-phase-noise MTCXO are better than ±0.45 ppm/−30 °C –+50 ° C, and measured phase noise results are better than −157 dBc/Hz at 1 KHz and −170 dBc/Hz at 10 KHz.

A Fully Integrated Oven Controlled Microelectromechanical Oscillator—Part I: Design and Fabrication

Abstract: This paper, the first of two parts, reports the design and fabrication of a fully integrated oven controlled microelectromechanical oscillator (OCMO). This paper begins by describing the limits on oscillator frequency stability imposed by the thermal drift and electronic properties ( $Q$ , resistance) of both the resonant tank circuit and feedback electronics required to form an electronic oscillator. An OCMO is presented that takes advantage of high thermal isolation and monolithic integration of both micromechanical resonators and electronic circuitry to thermally stabilize or ovenize all the components that comprise an oscillator. This was achieved by developing a processing technique where both silicon-on-insulator complementary metal–oxide–semiconductor (CMOS) circuitry and piezoelectric aluminum nitride, AlN, micromechanical resonators are placed on a suspended platform within a standard CMOS integrated circuit. Operation at microscale sizes achieves high thermal resistances ( $\sim 10~^{\circ }\text{C}$ /mW), and hence thermal stabilization of the oscillators at very low-power levels when compared with the state-of-the-art ovenized crystal oscillators, OCXO. A constant resistance feedback circuit is presented that incorporates on platform resistive heaters and temperature sensors to both measure and stabilize the platform temperature. The limits on temperature stability of the OCMO platform and oscillator frequency imposed by the gain of the constant resistance feedback loop, placement of the heater and temperature sensing resistors, as well as platform radiative and convective heat losses are investigated.[2015-0035]

Dynamics of temperature-frequency processes in multifrequency crystal oscillators with digital compensations of resonator performance instability

Abstract: Design and construction peculiarities of multifrequency crystal oscillators technically invariant to temperature effects have been considered. The analysis of thermodynamic characteristics of multifrequency temperature-compensated crystal oscillators was performed in conditions of nonstationarity of the thermal behavior of piezoelectric resonator. The volume density of heat source was determined during the excitation of quartz crystal resonator. Thermodynamic processes occurring in multifrequency crystal oscillators were investigated at the stage of settling of quartz crystal resonator oscillations. The need of taking into account the thermodynamic component during the investigation of high-speed thermal processes taking place in quartz crystal resonators was proved. The efficiency of using a multifrequency-algorithmic approach for ensuring the invariance of piezoresonance devices was estimated. It was shown that the use of this approach makes it possible to essentially reduce the temperature instability of crystal oscillators and reduce the up time of these devices due to a more exact compensation of initial frequency drifts.

5.9 A 37μW dual-mode crystal oscillator for single-crystal radios

Abstract: The emerging Internet of Things (IoT) market is fueled by reductions in power, cost and size of wireless sensors. Wireless nodes reduce average power by using intermittent data transmission, which is synchronized by a continuously operating sleep timer in each node. In some applications, such as disposable sensors, low cost and small physical size are more important than achieving the lowest possible power consumption. Crystal cost and size is a limitation, particularly because each node requires two crystals. The first crystal, in the MHz range, is used to generate the PLL reference clock. The second crystal, usually 32.768kHz, is used to generate an accurate sleep timer used for synchronizing data transmission. A radio SoC may occupy 4×4mm2 board area while a standard size for each crystal is 3.2×2.5mm2. Therefore, the size of the crystals can be larger than the SoC itself, limiting the applications.

Oven controlled FBAR oscillator

Abstract: Recent work with chip scale integrated FBAR oscillators has highlighted the fact that the temperature sensitivity is similar to SAW resonators. This sensitivity is significantly higher than quartz crystal oscillators, and limits the application of the technology. This investigation looks at the feasibility of stabilizing the frequency of the oscillator with a heater resistor and sensor resistor integrated into close proximity with the resonator, and an on-chip temperature feedback network.

Crystal oscillator startup time reduction

Abstract: In described examples, a circuit (100) includes a crystal oscillator (120) to generate an output frequency for a circuit. A driving oscillator (110) generates a startup signal having a driving frequency that is provided to activate the crystal oscillator (120). The driving frequency of the startup signal is varied over a range of frequencies that encompass the operating frequency of the crystal oscillator (120) to facilitate startup of the crystal oscillator (120).

Note: Ultra-stable digitally controlled oven

Abstract: This paper describes design and characterization of a digitally controlled double oven system. 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 digitally controlled oven crystal oscillator.

Measurement method and measurement system

Abstract: A measurement method includes: obtaining a first temperature characteristic of a crystal oscillator based on a plurality of oscillating frequencies observed when the crystal oscillator is temporarily energized at each of a plurality of temperatures around the crystal oscillator; observing a first oscillating frequency obtained by maintaining energization of the crystal oscillator after setting the temperature around the crystal oscillator to a first temperature of the plurality of temperatures; obtaining a second temperature characteristic of a oscillating frequency when energization of the crystal oscillator is maintained based on the first temperature characteristic and the first oscillating frequency; and normalizing the first temperature characteristic at a given temperature.

Reducing duration of start-up period for a crystal oscillator circuit

Abstract: A crystal oscillator circuit comprises a crystal (X 1 ); oscillator circuitry (31) for generating a crystal oscillation signal at an oscillation frequency; and a kick-start circuit (12) for injecting pulses into the crystal during a start-up period. The oscillator circuitry (31) comprises a differential pair of transistors (M 1 , M 2 ) and can operate in an oscillating mode or a start-up mode. In the oscillating mode, the differential pair of transistors are cross-coupled so that a gate terminal of one transistor (M- 1 ) is coupled to a drain terminal of the other transistor (M 2 ), and vice versa, and the drain terminals are coupled to the crystal (X- 1 ) to generate the crystal oscillation signal. In the start-up mode, the kick-start circuit (12) drives the gate terminals of the transistors (M- 1 , M 2 ) with said pulses. This crystal oscillator circuit has a decreased start-up time compared to prior art solutions and a reduced influence of parasitic oscillations.

Reliable crystal oscillator start-up

Abstract: The method concerns the reliable start-up of a crystal oscillator where the drive levels the crystal is subjected to are kept low in order to avoid over-driving the crystal. After applying a start-up value of a parameter controlling the drive level where the drive level associated with the start-up value is rather high such that reliable start-up is ensured the parameter is modified step-wise so as to reduce the drive level until the crystal oscillator ceases to operate regularly. To assess whether this is the case, the frequency of the crystal oscillator is compared with the frequency of an auxiliary oscillator. A safety margin is added to the parameter and the result stored in a non-volatile memory as an operating value. The crystal oscillator is then restarted with the start-up value and after a delay the operating value is applied.

Kyropoulos method sapphire crystal oven capable of being remotely observed

Abstract: The utility model discloses a kyropoulos method sapphire crystal oven capable of being remotely observed. A controller capable of carrying out centralized control, a seed crystal rotating system capable of driving a seed crystal rod to rotate, a seed crystal lifting system capable of driving the seed crystal rod to vertically move, a weighing system for measuring the weight of a crystal, a temperature measuring system for measuring temperature of cooling water, a vacuum system for achieving the vacuum environment of long crystals, a heating system for achieving the high-temperature environment, a display interface for parameter and information display and a sleeve arranged on an oven cover of the sapphire crystal oven are arranged. A camera system is arranged in the sleeve, a sealing part is arranged at the lower end of the sleeve, and comprises plane quartz glass and a rubber ring, and the camera system is connected with the controller. According to the scheme, the growth condition of the sapphire crystal can be more conveniently observed, and therefore the success rate of crystal introducing is improved.

Measuring reactive near-field interference using the quartz oscillators intermodulation

Abstract: A quartz oscillator is susceptible to electromagnetic interference (EMI). To evaluate the effect of EMI, this research used the same quartz oscillator circuit for transmitter(s) and receiver(s), but with distinct quartz crystal (QC) frequencies. An equivalent impedance change occurred because of the reactive near-field feedback on the quartz oscillator. The strength was roughly proportional to the inverse transmitter-to-receiver distance. The unhoused QC, which functioned as a parallel and perpendicular receiver to the transmitter, displayed nondirectional and unidirectional radiation patterns, respectively. The intermodulation of the EMI transmitted from the QC oscillator was recognizable in the superposition feature.

A differential coupled frequency doubling voltage-controlled crystal oscillator in a 0.35 μm CMOS process

Abstract: This paper presents a high-performance differential coupled frequency doubling voltage-controlled crystal oscillator (VCXO). Frequency doubling and low phase noise are realized through a novel gm-boosted differential Colpitts oscillator. Distributed varactor arrays are used to obtain wide frequency tuning range and high tuning linearity simultaneously. The proposed VCXO is fabricated in a 0.35 μm 2P3M standard complementary metal-oxide semiconductor process at a supply voltage of 3.3 V, and the power dissipation is 7 mW. Measurement results show that the designed VCXO achieves ±135 ppm output frequency variation range with 5 % linearity and ?133 dBc/Hz phase noise at 1 kHz frequency offset by using a 40 MHz fundamental AT-cut crystal resonator.

Novel gyroscopic mounting for crystal oscillator (payload) applied in high dynamic host vehicle (platform) to improve its output stability

Abstract: When crystal oscillator applied in high dynamic host vehicle, dynamic loads impact its short and medium-term stability. In order to suppression and/or reduction these impacts, gyroscopic mounting is proposed to install oscillator on it.

Start-Up Acceleration of Quartz Crystal Oscillator Using Active Inductance Double Resonance and Embedded Triggering Circuit

Abstract: Low-frequency double-resonance quartz crystal oscillator was developed with active inductance circuit aiming the start-up of stable oscillation of tuning fork-type quartz crystal resonator at 32.768 kHz within 0.37 ms. The initial oscillation is triggered by a part of crystal oscillator forming a CR oscillator. The negative resistance ranges to 4 MΩ at gmf of 4.1 μA/V. In a limited frequency range, the circuit shows negative reactance Ccci = -3.4 pF equivalent to inductance Lcc = 9.8 H. The Allan standard deviation indicated 10-11 to 10-10, showing high stability comparable to general quartz crystal oscillator.

Design of multiple-standard signal source for quartz wafer testing

Abstract: This paper designs a high-precision signal source based on DDS (Direct Digital Frequency Synthesis) technology for the needs of quartz wafer parametric testing system in π-network. Using Oven Controlled Crystal Oscillator (OCXO) as the time base, the signal source uses AD9959 integrated chipof the AD Company in American, and is controlled by ARM micro-controller.The signal source can generate four-channel sinusoidal signals whichranges from1 to 200MHz and itsfrequency, phase and amplitude can be independently adjusted. This technologyprovides technical support for quartz wafer parametric testing system and improves the accuracy of measurement of quartz wafer. This paper analyses the equivalent circuits of quartz wafer unit, the π-network, the select of chips, the principle of DDS technology and the hardware and software design of DDS signal source. Among them, AD9959 is a high-performance DDS chip with four channels, and its internal clock frequency can reach 500MHz, furthermore, the chip is integrated with four independent DDS channels and its composed of 32-bit frequency control registers; The STM32F407 chip is used which comes with three 12-bit ADCs, two 12-bit DACs and two USB ports and can simplify the external circuit and facilitate the realization of the control of the entire system, so it provides convenient conditions for the testing system. The experimental results show that the frequency error of the signal source is less than ± 0.1ppm, and the accuracy of the series resonant frequency of the quartz wafer testing system can reach ± 2ppm when using the signal source.Compared with the testing instruments widely used in China, which are based on oscillator and impedance testing methods, this testing system has the advantages of wide frequency testing range, fast frequency switching speed, high frequency resolution and accuracy. The signal source meets the requirements of the quartz wafer testing system very well.

Design of Frequency Output Pressure Transducer

Abstract: Piezoelectricity crystal is used in different area in industry, such as downhole oil, gas industry, and ballistics. The piezoelectricity crystals are able to create electric fields due to mechanical deformation called the direct piezoelectric effect, or create mechanical deformation due to the effect of electric field called the indirect piezoelectric effect. In this thesis, piezoelectricity effect is the core part. There are 4 parts in the frequency output pressure transducer: two crystal oscillators, phase-locked loop (PLL), mixer, frequency counter. Crystal oscillator is used to activate the piezoelectricity crystal which is made from quartz. The resonance frequency of the piezoelectricity crystal will be increased with the higher pressure applied. The signal of the resonance frequency will be transmitted to the PLL. The function of the PLL is detect the frequency change in the input signal and makes the output of the PLL has the same frequency and same phase with the input signal. The output of the PLL will be transmitted to a Mixer. The mixer has two inputs and one output. One input signal is from the pressure crystal oscillator and another one is from the reference crystal oscillator. The frequency difference of the two signal will transmitted to the frequency counter from the output of the mixer. Thus, the frequency output pressure transducer with a frequency counter is a portable device which is able to measure the pressure without oscilloscope or computer.

Ultra-low phase noise frequency synthesis chains for high-performance vapor cell atomic clocks

Abstract: This paper presents the development of a 9.192 GHz microwave frequency synthesis chain (absolute and residual noise characterization) dedicated to be a local oscillator (LO) in a high-performance cesium vapor cell atomic clock based on coherent population trapping (CPT). The key components are an ultra low noise oven controlled quartz crystal oscillator (OCXO), multiplied to 9.2 GHz using a non-linear transmission line. A dielectric resonator oscillator (DRO) is phase-locked onto the microwave signal to generate the 9.192 GHz frequency. The absolute phase noise of the LO has been characterized at the level of −42, −100, −117 dBrad2/Hz and −129 dBrad2/Hz at 1 Hz, 100 Hz, 1 kHz and 10 kHz offset frequencies respectively. With such performances, the expected Dick effect contribution to the atomic clock short term frequency stability is reported to 6.2×10−14 at 1 s integration time. Main limitations are pointed out.

Realization of automatic test system of crystal oscillator inside the universal counter

Abstract: This thesis introduces the working principle of the universal counter frequency and period measurement and expounds the important function of the crystal oscillator inside universal counter. This paper designs a system which uses the technologies of time-sharing control and video capture to realize the automatic test of multiple crystal oscillators inside the universal counters at the same time.

Non-linear optical device with C18H16N2O2 single crystal and preparation method of non-linear optical device

Abstract: The invention relates to a C18H16N2O2 non-linear optical device and a preparation method thereof. The C18H16N2O2 crystal can be prepared by using a spontaneous crystallization cooling method and a seed crystal method, and the growing method of the C18H16N2O2 crystal is simple, easy to operate and low in cost; the prepared C18H16N2O2 non-linear optical crystal has a relatively wide penetration wave section of 0.55-2.2mu m, the powder frequency-doubled effect intensity of the C18H16N2O2 non-linear optical crystal is of 2-3 times of OH1, and the C18H16N2O2 non-linear optical crystal is stable in physical and chemical property and free from deliquescence; the C18H16N2O2 non-linear optical crystal can be used for preparing a non-linear optical device, and at the room temperature, an Ho:Tm:Cr:YAG Q-adjusting laser is used as a light source for inputting infrared light of which the wavelength is 2090nm and outputting infrared laser of which the wavelength is 1045nm; the C18H16N2O2 non-linear optical device comprises a device in which at least one beam of incident electromagnetic radiation passes through at least one piece of the C18H16N2O2 single crystal so as to generate at least one beam of output radiation of which the frequency is different from that of the incident electromagnetic radiation; the device can be a terahertz wave generator, a secondary harmonic generator, an upper frequency converter, a lower frequency converter or an optical parametric oscillator.

C17H13NO2S nonlinear optical crystal, and preparation method and use thereof

Abstract: A C17H13NO2S nonlinear optical crystal does not have a symmetrical center, and belongs to a monoclinic system, the space group is Cc, and cell parameters are characterized in that a is 2.0924nm, b is 0.55952nm, c is 1.1691nm, alpha = gamma = 90DEG, beta = 90.568DEG, Z is 4, and V is 1.3686nm . The crystal grows through a spontaneous crystallization volatility process, a spontaneous crystallization process or a seed crystal process; the growth speed is fast, the cost is low, and large-size high-quality crystals can be easily obtained; and the obtained crystal has large nonlinear optical effects, has a frequency multiplication effect intensity 1.5-2.5 times that of OH1, has stable chemical properties, is non-deliquescent, is suitable for infrared waveband laser variable frequency needs, and can be used to make nonlinear optical devices including a device for generating at least one beam of output radiation with the frequency different from the frequency of incident electromagnetic radiation by allowing at least one beam of the incident electromagnetic radiation to go through at least one of the crystal.

Evaluation of the lower limit of crystal oscillator noise through the resonator's design parameters

Abstract: This article discusses the method of determining the lower limit of the noise level of precision crystal oscillators based on the calculation of the crystal's maximum excitation power. Power limit is determined by the limiting values of the mechanical stresses arising from the excitation of the thickness-shear waves, and takes into account the design parameters of the resonator, such as natural frequency, the number of mechanical harmonic, curvature radius of the lens surface of the piezoelectric element, and the radius of the electrodes. In this paper we derive formulas for practical calculation of the lower noise level resonators of AT - cut.