Topic
Crystal oven
About: Crystal oven is a research topic. Over the lifetime, 955 publications have been published within this topic receiving 10380 citations. The topic is also known as: oven-controlled crystal oscillator & OCXO.
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19 Mar 2015
TL;DR: A dual mode crystal oscillator has been implemented that can be used both as the reference clock for the radio PLL in a high performance mode the sleep timer in a low power mode, enabling a low and small form factor design.
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.
13 citations
Patent•
29 Oct 2008TL;DR: In this article, a temperature compensated frequency estimate for a crystal oscillator is presented, wherein the temperatures of the crystal and oscillator are both accounted for, and the difference between the oscillator temperature measurement and a second temperature is scaled, and used to generate a second frequency component.
Abstract: Method and apparatus for generating a temperature compensated frequency estimate for a crystal oscillator, wherein the temperatures of the crystal and oscillator are both accounted for. A crystal temperature measurement is used to generate a first frequency component. The difference between the oscillator temperature measurement and a second temperature is scaled, and used to generate a second frequency component. The first and second frequency components may be summed to produce a frequency estimate for the crystal oscillator. In an embodiment, the computations may be performed in the slope domain.
13 citations
TL;DR: It is shown that oven-controlled micro electromechanical systems (MEMS) oscillators have the potential of attaining a higher frequency stability, with a lower power consumption, than temperature-compensated crystal oscillators (TCXOs) and the currently manufactured MEMS oscillators.
Abstract: It is shown that oven-controlled micro electromechanical systems (MEMS) oscillators have the potential of attaining a higher frequency stability, with a lower power consumption, than temperature-compensated crystal oscillators (TCXOs) and the currently manufactured MEMS oscillators.
13 citations
Patent•
19 Feb 2002TL;DR: In this article, a GPS-satellite receiver comprises a crystal oscillator that is affected by local ambient temperature in a repeatable way, and the receiver is used to calculate the true frequency bias of the local oscillator.
Abstract: A navigation-satellite receiver comprises a crystal oscillator that is affected by local ambient temperature in a repeatable way. After locking onto a GPS satellite, the receiver is used to calculate the true frequency bias of the local crystal oscillator. GPS-system lock provides an atomic-clock basis for such measurements of true frequency. The current temperature of the crystal is measured and recorded in association with the true frequency bias measurement. The data is then used to generate a ninth-order polynomial that describes the frequency drift of the crystal over temperature. Then during receiver initialization when the local reference oscillator is not in lock, the ambient temperature is measured and used to index the ninth-order polynomial to estimate the actual crystal frequency. Such frequency estimate is then used as a basis to find signal from visible SV's in an overhead constellation.
13 citations
TL;DR: An improved 5 MHz reference oscillator for use in time and frequency standards has been developed in this article, using an improved crystal unit, reaching a long term drift rate of less than 1×10-11 per day in a few days.
Abstract: An improved 5 MHz reference oscillator for use in time and frequency standards has been developed. This oscillator, using an improved crystal unit, reaches a long term drift rate of less than 1×10-11 per day in a few days. The design includes precautions for reduction of effects of conducted electrical noise on the output frequency. Modular design of functional circuits provides ease of manufacture and uniformity of the product. Stabilized temperature control circuits have been utilized to provide improved oven performance. The oscillator has been tested for the effects on frequency and phase stability of power supply variation, changes in thermal environment, modulation by electrical noise, and mechanical vibration. Phase noise within the range of 100 Hz through 5.0 kHz varies from -120 dB to -125 dB.
13 citations