Showing papers on "Crystal oven published in 2016"

5.9 A 24MHz crystal oscillator with robust fast start-up using dithered injection

Abstract: Wireless nodes in Internet-of-Everything (IoE) applications achieve low power consumption by operating the radio at very low duty cycles. The wireless node spends most of its time in sleep, waking only occasionally to transmit or receive data. For some standards, such as Bluetooth Low Energy (BLE), the data or advertising packet length can be less than the time it takes the crystal oscillator, which is used as the reference clock for the radio's PLL, to turn on. Figure 5.9.1 shows a simplified power profile for a node with a typical BLE advertising packet length. A significant fraction of energy used for each RX/TX burst is used to turn on the oscillator. For applications where average power is not dominated by sleep power, the crystal oscillator start-up time can be a large contributor to average power consumption.

Frequency reference for crystal free radio

Abstract: To reduce the cost of a sensor node, complete system integration implies zero external components. A system solution is therefore presented to calibrate the frequency of an on-chip relaxation oscillator to be used as a frequency reference for low power crystal free wireless communication.

Temperature and trim effect compensation of a VCXO using a multidimensional segmented polynomial array

Abstract: Voltage Controlled Crystal Oscillators (VCXOs) are widely used and well known frequency control products. VCXOs are typically characterized by having wide frequency pulling ranges (greater than ±50ppm). These oscillators are also uncompensated for temperature performance. This means temperature performance of ±20ppm or more is typical over the industrial range of −40 to 85 °C. Trim effect is a skewing of the frequency versus temperature performance of a crystal oscillator as the frequency is pulled (trimmed) away from the oscillator's nominal frequency. Even though unwanted, the degradation of performance from trim effect is something generally accepted as a characteristic of VCXOs. This paper focuses on a method of compensating crystal oscillator temperature and trim effect using a multi-dimensional segmented polynomial array. The inherent trim effect has been reduced from approximately ±11ppm down to ±0.5ppm. This is a 22-fold improvement over the inherent performance. The theory of this compensation method will be discussed, and data showing the results of temperature and trim effect compensation on actual oscillators will be presented.

Development of high-stability miniaturized oven controlled crystal oscillator

Abstract: This paper reports on the development of a high-stability miniaturized Oven Controlled Crystal Oscillator (OCXO) in the size of 9.7 mm × 7.5 mm based on the analog oscillation circuit combined with the conventional temperature sensing circuit using a thermistor and related discrete electrical components. The finite element method (FEM) is implemented to optimize the oven stability of the oven structure. As a result, a highly stable oven performance less than ±1°C variation within the ambient temperature ranging from −40 to 85°C is both numerically analyzed and experimentally demonstrated. Consequently, this result implies that the frequency stability of the miniaturized OCXO can achieve less than ±20 ppb using an AT-cut crystal.

An ovenized CMOS-MEMS oscillator with isothermal resonator and sub-mW heating power

Abstract: This work reports an ultra-low-power temperature-compensated CMOS-MEMS oscillator based on an uniform temperature design that ensures low temperature gradient of the proposed resonator to attain high frequency stability. The oven heating efficiency greater than 140°C/mW is achieved in this work by a proper thermal isolation design. In addition, the lowest temperature coefficient of frequency (TCf) of 2.84 ppm/°C is also accomplished through a passive temperature compensation scheme. The performance of the ovenized oscillator is evaluated by Allan deviation where the frequency instability of 95 ppb / 32 ppb is characterized for the oven on/off conditions, respectively, which is on par with state-of-the-art silicon-based MEMS oscillators.

Analysis of the crystal oscillators phase noises and methods of their reduction

Abstract: The article determines main components of the communication devices phase noises and observes methods of measurement and assessment of main components of quartz oscillators phase noises. A practical study of the parameters of crystal oscillators and the means of optimizing of the phase noises introduced by them was conducted. The article introduces a method for reducing the noises with thermostat structural means, in order to increase thermodynamic stability of the quartz resonator. Factors affecting the level of noises are observed, depending on the manufacturing technology of the quartz resonator. According to the results of the experimental data the article provides recommendations for their reduction.

Heating and thermostatic analysis of an oven-controlled quartz crystal oscillator

Abstract: An oven-controlled crystal oscillator (OCXO) uses thermostatic regulation to stabilize the output frequency by maintaining the temperature of the quartz crystal oscillator at a fixed level. The OCXO is heated by a chip which holds the temperature of the device at a working level of between 80 and 105 °C to stabilize the output frequency. In this study, finite element analysis was used to simulate heating of the OCXO element. The heating temperature vs. time change, when heat is transferred to the quartz crystal, and the quartz crystal thermostatic time variation vs. the quartz temperature distribution, were both investigated. The results were compared by simulation of the behavior of the quartz oscillator in a nitrogen and helium environment and also under vacuum.

Recent progress in the performances of ultrastable quartz resonators and oscillators

Abstract: Stressed compensated (SC) cut led recently to the best frequency stability ever obtained with a quartz oscillator, 2.5 × 10−14 for the flicker frequency modulation (FFM) floor. This result is confirmed in this paper with a 3.2 × 10−14 ± 1.1 × 10−14 . The quartz resonator is integrated in a 5 MHz enhanced aging box double oven controlled oscillator. After reminding a bit of history, this paper describes how the first significant development in terms of ultra-stable quartz state-of-the-art oscillators was performed in the last 20 years, how the resonators were chosen, and main information about the development of adequate electronics and how to mechanically and thermally stabilized such an ultra-stable oscillator. We also present how to characterize the expected performances, and hot topics in quartz based oscillators.

An Ultra Stable Oscillator for the 3GM experiment of the JUICE mission

Abstract: An Ultra Stable Oscillator is being developed by AccuBeat (named USO) for the Gravity and Geophysics of Jupiter and the Galilean Moons (3GM) radio occultation experiment of the ESA JUICE mission. This paper reviews the oscillator design and the critical issues to be tackled. The USO is a compact 15×13×10cm3 oscillator, based on a quartz crystal resonator and highly stable double oven. A Partial Engineering Model of (PEM) was built and tested in thermal vacuum. The PEM with 5MHz output has demonstrated a frequency stability below 2E-13 for a at averaging times of 1s to 1000s, thus meeting the requirements for technology readiness level 5 (TRL 5), according to the ECSS.

A novel voltage controlled temperature compensated crystal oscillator for eliminating the trim effect

Abstract: A novel scheme of voltage controlled temperature compensated crystal oscillator (VCTCXO) which could realize frequency adjustment and temperature compensation simultaneously is presented. The scheme is based on the binary function V = F(T, f t ) which could be obtained from the temperature experiments, where f t is the target output frequency (controlled and adjusted by external control voltage); T is the ambient temperature and V is the compensating voltage. Through extending the two-dimensional temperature-frequency characteristics curve to three-dimensional surface and using a microcontroller to works out compensating voltages according to the above binary function, this new approach provides the possibility for eliminating the adverse influence of trim effect on traditional temperature compensated crystal oscillators (TCXOs).

Crystal oscillator circuit with reduced startup time

Abstract: A crystal oscillator achieves fast start-up by injecting an in-band periodic signal into the crystal oscillator driver circuit. The in-band periodic signal has a frequency that is within a bandwidth of the crystal oscillator. Injection of the in-band periodic signal begins in response to a power-up condition and stops after a predetermined time period corresponding to the amount of time it takes to ensure the crystal driver is achieving full swing.

Low power consumption techniques of quartz crystal oscillator

Abstract: Crystal oscillators are one of the main components used in the most electronic circuits, especially in the applications of radio frequency and microprocessor devices. Several techniques are being used to have low power consumption of crystal oscillator such as low voltage supply; low current, and improvise the designing of the circuit. The improvement of the crystal oscillator is also desired for the high speed and long lifetime devices.

Resonant Frequency Measurement of Quartz Crystal Based on DDS and Real-Time Peak Searching

Abstract: In order to solve the unstable problem of conventional methods for measuring resonant frequency of quartz crystal, a method based on DDS (Direct Digital Synthesis) and real-time peak searching is proposed to increase stability of measurement. By actively generating excitation signal using DDS, the response of quartz crystal can be obtained even under heavy load. Frequency response of impedance is studied to reveal the relationship between minimum impedance and resonant frequency. Electric circuit and real-time searching algorithm is designed to track resonant frequency of quartz crystal. Experimental results show when parameter of quartz crystal changes 392.0%, the resonant frequency could still be measured by the developed method.

Stable ring oscillator for ultra low supply voltages

Abstract: This paper presents an alternative to crystal based oscillators for reference frequencies in highly integrated SoCs. The frequency reference through the usage of an active bias controlled ring oscillator operating with a supply voltage from 300 to 500 mV for an temperature from −40 to 125 ° C. The oscillator shows a very good temperature and supply voltage frequency stability coming from the active biasing using a stable current reference.

Enhanced clock based on the Chip Scale Atomic Clock and Dual-Mode Crystal Oscillator

Abstract: In this paper we introduce enhanced low power clock system that is able to achieve frequency stability ±001 ppm over a wide temperature range, which is approximately 100 times better than the stability achievable with typical Temperature Compensated Crystal Oscillator (TCXO) The proposed clock system is based on Dual-Mode Crystal Oscillator (DMXO) and the Chip Scale Atomic Clock (CSAC) Power consumption of the clock system is comparable with the power consumption of the CSAC (Symmetricom SA45s) in the low power mode Typical power consumption of the CSAC is approximately 120 mW in a normal full accuracy mode (±001 ppb) In the low power mode, the CSAC operates as simple TCXO and consumes less than 20 mW of power; however over a wide temperature range, the frequency stability is limited to ±1 ppm

Oven controlled crystal oscillator using embedded heating device package

Abstract: An oven controlled crystal oscillator using an embedded heating device package is disclosed. The oven controlled crystal oscillator, which is different from the conventional technology using a heating source independent from a quartz crystal package, integrates a heating resistor in a ceramic package structure of the quartz crystal and cooperates with a temperature-controlled circuit to heat a quartz blank in the quartz crystal package, thereby shortening thermal conduction paths, increasing thermal conduction efficiency and greatly reducing thermal dissipation. The present invention further uses an exterior and independent heating resistor, combining with the heating resistor in the quartz crystal package and controlled by the temperature-controlled circuit to form a sandwich structure so that heat is more concentrated to use, thereby stabilizing the interior temperature of a constant temperature oven and the output frequency of an oscillator.

Design and implementation of calibration circuit for crystal oscillator

Abstract: High performance crystal oscillator is usually used as the clock source of system timer in a miniaturization space aircraft, however, it cannot overcome the effect of long-term aging on accuracy. Thus, this paper presents a simple, light and efficient circuit to calibrate the difference between the actual output frequency and the nominal frequency of a crystal oscillator periodically in real time. The experiments show that the proposed design reduces the timing deviation from more than 1614ms to less than 1ms in 5 hours. The timing error is less than the required error index, which gives strong support to the working timer of a space aircraft.

Parametric frequency transformation in a superconducting waveguide line with an integrated Josephson oscillator

Abstract: The parametric frequency division in a coplanar waveguide line with an integrated single-contact rf SQUID (Josephson oscillator) is discussed. It is assumed that the oscillator is excited by pump pulses whose carrier frequency can be a multiple of the plasma frequency of the oscillator. It is shown that the Josephson oscillator excited at the pump frequency can induce frequency division by emitting subharmonics that are multiples of the fundamental frequency (fractional resonances). Parameters for which parametric frequency transformation occurs are determined. The possible generalization of this effect to the quantum case in which correlated microwave photons (entangled photon states) can be generated is discussed.

Temperature-compensated crystal oscillator simulation in stress compensated cut crystal resonators

Abstract: Traditional quartz crystal frequency references include a large, power-starving, oven-controlled crystal oscillator (OCXO), which base stations favor because of their excellent stability. We simulated a temperature-compensated crystal oscillator (TCXO) in the stress-compensated cut (SC-cut) resonator using the C and B mode frequencies. Power-conscious base-station manufacturers use the compensation circuit combination of TCXOs. The large frequency change in the B mode will be employed in temperature compensation for the C mode. First, we examined the circuit that could drive the C mode and B mode by simulation at the same time.

The method for forming time intervals with crystal oscillator frequency instability compensation

Abstract: This paper proposes a method for two orders reduction of a time interval formation error for autonomous complexes and navigation, location and communication systems.

Seeding temperature capturing method for crystal growth adopting czochralski method and automatic capturing equipment

Abstract: The invention discloses a seeding temperature capturing method for crystal growth adopting a czochralski method. The method comprises the steps that a crucible for containing a crystal material in a crystal oven is heated at a constant speed with a certain heating rate to the target temperature, and the target temperature is higher than that of a melting point of the crystal material; a curve formed by crucible temperature changing along with time in the temperature rising process is obtained, and the temperature corresponding to a point with the maximum slope in the curve is selected as seeding temperature. According to the seeding temperature capturing method for crystal growth adopting the czochralski method, only by means of simple heating operation, the seeding temperature of a crystal can be selected by utilizing the curve of the temperature changing along with the time in the temperature rising process. The invention further provides automatic capturing equipment for the seeding temperature, a seeding temperature obtaining unit is used for obtaining the curve of the temperature changing along with the time in the temperature rising process, so that the seeding temperature of the crystal is selected and obtained, the influence on seeding operation from labor experience is excluded, and the seeding temperature of the novel crystal can be judged accurately.

High-resolution computer-controlled oscillator of 2-mm wave-range for the low temperature dielectrometer

Abstract: High-resolution computer-controlled oscillator of 2-mm wave-range intended for the low temperature dielectrometer was designed and constructed. The proposed oscillator unit may be used as free-running source as well as phase locked source being included to the frequency synthesis system. Dependence of dielectric loss vs temperature for some diamond-like materials was measured using proposed oscillator unit within frequency range 110 and 145 GHz and at temperatures within 1 and 300 K.

Optimization for phase noise in cross-coupled integrated quartz crystal oscillator

Abstract: In order to solve the disadvantages of Leeson model in studying the phase noise of quartz crystal oscillator, an optimized model for integrated quartz crystal oscillator was established by decomposing the whole circuit into the amplifier module and the resonator module. Subsequently, simulation was carried out by Cadence to verify the optimized model. According to the optimized model, at ƒc=20MHz, the circuit parameters such as the ratio of width to length of MOSFET and the value of capacitance and resistance were optimized. Results indicate the phase noise of optimized integrated quartz crystal oscillator were −155dBc/Hz@1kHz and −164dBc/Hz@10kHz, respectively.

Periodic kickstarter for a crystal oscillator

Abstract: A cyclical pulsing oscillator having a pulse repetition rate close to a crystal resonant frequency in an oscillator provides more useful start-up energy to the crystal oscillator circuit and thus provides much faster start-up time. The start-up pulsing oscillator runs for a number of cycles or until the crystal oscillator amplitude as built up to a desired value. The pulsing oscillator may have a repetition rate of from about one-third to about one-half the crystal resonant frequency, thus providing more useful start-up energy to the crystal oscillator circuit.

A four point mount 5×7 mm high reliability crystal oscillator for extreme environmental applications

Abstract: High reliability crystal oscillators for extreme operating environments demands unique designs and processes for both the crystal and oscillator components. This paper addresses the development of a hybrid 5×7 mm AT cut crystal and oscillator circuit for extreme environment applications like jet engine controls, oil and gas well-logging including measure while drilling, geothermal systems, space craft and military. The temperature ranges include −65°C to 250°C with reliability tests to 275°C. Currently, these designs cover the frequency range of 312.5 kHz to 85 MHz and −65°C to 200°C for 312.5 KHz to 160 MHz and supply voltages of +1.8Vdc, +2.5Vdc, +3.3Vdc and +5Vdc.