Oscillators1. Clock OscillatorsA timing device that consists of a crystal and an oscillator circuit, providing an output wave at a specified reference frequency. The crystal oscillators are divided into categories according to their basic characteristics: Package oscillators / package crystal oscillators (PO/PXO). The frequency depends on the oscillators. Temperature variations essentially influence the crystal. Depending on the operating temperature range, the frequency stability lies between 100 ppm and 10 ppm. These oscillators are used in microprocessors, computers and PCM-systems. 2. Voltage Controlled Crystal Oscillators / Voltage Controlled Oscillators (VCXO / VCO) The output frequency of these oscillators is changed or modulated by an external voltage. VCXO are utilized in communication and electronic equipment mostly as frequency modulators (radio transmission systems) and as a part of phase locked loops. 3. Temperature Compensated Crystal Oscillators (TCXO) By means of analogue or digital compensation methods the variation of frequency over the temperature range is stabilized. Depending on the temperature range the frequency stability is between 0.5ppm and 5ppm. TCXO are mostly used in mobile radio equipment and mobile radio stations as GSM or AMPS systems. Further applications are navigation systems and measurement systems (frequency counter, synthesizer). 4. Voltage Controlled Temperature Compensated Crystal Oscillators (VCTCXO) The VCTCXO is a combination of the features from TCXO and VCXO. It combines the features of a temperature stabilization of the oscillator frequency (TCXO) and the possibility to modulate the frequency by an external signal (VCXO). Unlike the pure VCXO the variation range is smaller. 5. One Time Programmable Crystal Oscillators A programmable crystal is provided having a memory for storing frequency-defining parameters. Typically, one of these parameters is used to program an adjustable capacitive load circuit coupled to a crystal to thereby adjust the crystal source frequency. Additional parameters are used to program the output frequency of a phase locked loop circuit coupled to receive the adjusted source frequency. A further parameter can also be used to divide the output frequency of the phase locked loop circuit to supply a specified output frequency. Programmable oscillators did as promised and cut delivery times to mere days. Nevertheless, they are relatively noisy compared with traditional oscillators and therefore can only be used in selected applications such as low volume production and microcontrollers where noise is not a problem. Programmable oscillators are also useful for quick turnaround in prototyping applications, however ordering conventional custom oscillators for the actual production runs can rectify noise issues. 6. MEMS Oscillators MEMS literally means Micro Electro-Mechanical Systems. MEMS structures exist today as miniature mechanical and/or electromechanical structures designed to perform tasks that previously were done with much larger mechanical structures. The major benefits of MEMS devices are much smaller size, much lower power, and much lower cost. There are many MEMS structures in high volume today, including sensors, pressure gauges, and video projection TV. CMOS resonators are a breakthrough technology that can replace Quartz Crystal and Ceramic Resonators as the frequency source in most electronic systems. In addition to offering performance advantages versus existing technologies, CMOS resonators are typically smaller, lower power; and because they can be manufactured in most CMOS fabrication facilities around the world, they offer significant advantages in total manufacturing capacity, and lower cost. CMOS Resonators are just beginning their learning curve, and are expected to follow Moore’s Law on future size and cost reduction capabilities. CMOS resonators also offer a path towards IC integration which is not possible with non-CMOS products. In the column details of the table below, you will find further information to the selected component. Pour tout renseignement, n'hésitez pas à appeler le 02 41 80 19 87. Mme Brigitte Drouot, e-mail se fera un plaisir de répondre à vos demandes.
  
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