A Voltage Controlled Crystal Oscillator (VCXO) is an electronic oscillator whose oscillation frequency is controlled by externally applied input voltage. The applied voltage determines the instantaneous frequency of oscillation. The basic circuit of VCXO comprises a standard crystal oscillator along with an electronic means of tuning the frequency, usually achieved using diodes. Say no to plagiarism. Get a tailor-made essay on "Why Violent Video Games Shouldn't Be Banned"? Get an original essay Typically, the oscillation frequency ranges from 30 ppm/volt to 50 ppm/volt. Commonly, VCXO is found in this frequency range. The frequency cannot be pushed too far because as the capacitance increases, the performance activity of the crystal is reduced. They are widely used in broadcasting and telecommunications equipment. They are used to design signals for clock generation. They are generally used in narrowband phase-locked mode to provide frequency variations. Parameters Frequency: Generally specified in MHz for frequencies above 1.0 MHz or in kHz below this. This must be specified with the correct number of decimal places to allow the manufacturer to determine the required frequency. Result: VCXOs are needed for a variety of applications. Some might be used to drive different forms of logic, while others might be needed for analog applications. Therefore, output requirements are an important element of the overall specification. Frequency Stability: The basic frequency stability of VCXOs is generally specified for room temperature, 20°C, and with the voltage control point set to its center value. The frequency is specified in terms of parts per million, ppm. Standard stability specifications are generally ±25 ppm, ±50 ppm and ±100 ppm. Supply Voltage: You must specify the supply voltage to ensure that it will work within the drive it is intended for. Ideally it should be able to operate outside the expected tolerance of the supply so that any slight discrepancies do not cause problems. Operating Temperature Range: Most units have an operating temperature range within which they will operate. Therefore it is necessary to specify a range for the VCXO. There are three main ranges: 0 - 70° C - Often referred to as the commercial temperature range. It is normally satisfactory for operation in office or laboratory environments. -10 - + 70°C - Industrial range necessary where temperature ranges can vary more widely. -40 - +85°C - approaches the military range (normally - 40 to +125°C) and is required where much wider temperature ranges are needed. For example for equipment that can be used externally. Pullability: Pullability is the frequency range over which the VCXO can be pulled for a given change in control voltage. It is specified in terms of parts per million, ppm, for a given voltage. As expected, higher pullability values ​​provide a wider tuning range, but VCXOs with lower pullability levels offer greater stability and lower phase noise. Please note: this is just an example. Get a custom paper from our expert writers now. Customize essayPackage: You need to specify the package as VCXOs come in many shapes and various options may be available from hole mount to surface mount. Beyond that, options such as tape and reel are often available for large-scale production.