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Epson Crystal Oscillator Agent Introduces Four Crystal Oscillators for You

Release date:2018-12-26 Author:Guan Shuo Click:

Epson Crystal Oscillator Agent Introduces Four Crystal Oscillators for You

1. Simple Crystal Oscillator (XO)

This is the most basic type, and its stability is completely determined by the inherent characteristics of the crystal resonator itself. Higher frequency crystals in the MHz range are made of quartz rods, which can provide relatively stable frequencies even if the ambient temperature varies from - 55 to + 125 (- 67 F to + 257 F). Even in such a wide temperature range, the stability of (+25 ppm) can be achieved by properly cutting quartz crystals. Compared with other passive resonators, such as LC oscillator circuits, which vary with temperature up to 1% (10,000 ppm) or higher, the performance of crystal oscillator has been greatly improved. But for some applications, even 25 ppm is not good enough, so additional measures must be taken.

2. Constant Temperature Controlled Crystal Oscillator (OCXO)

For some applications, the frequency-temperature stability index of TCXO still can not meet the requirements. In these cases, OCXO may be required. As the name implies, an oscillator with a baking chamber heats the crystal to a higher temperature, but it is still controlled, so that the temperature of the crystal remains stable even if the ambient temperature changes greatly. Because the temperature of the crystal and the sensitive part of the oscillator change very little, the frequency-ambient temperature stability has been significantly improved. In the range of ambient temperature, the stability of OCXO can reach 0.001 ppm. However, this increase in stability comes at the expense of increasing power consumption, and of course energy is needed to provide heat to the oven. Typical OCXO may require 1 to 5 W power to maintain internal temperature. After startup, it also needs to wait for the warm-up time of stable temperature and frequency, depending on the type of crystal oscillator, the warm-up time usually ranges from 1 minute to more than 10 minutes.Epson crystal oscillator agent


3. Voltage Controlled Crystal Oscillator (VCXO)

In some applications, it is expected that the frequency of the oscillator can be tuned or adjusted so that the phase-locked loop (PLL) can be used as a reference or may be used to adjust the waveform. VCXO provides this function through electronic frequency control (EFC) voltage input. For some special components, the tuning range specifications of VCXO may range from 10 ppm to 100 ppm (or even higher).

4. Temperature Compensated Crystal Oscillator (TCXO)

If the natural frequency and the temperature stability of quartz crystal can not meet the application requirements, the temperature compensation unit can be used. TCXO uses temperature sensing elements and a circuit that generates a voltage curve. In the whole temperature range, the voltage curve is completely opposite to the frequency change trend of the crystal, so it can ideally offset the drift of the crystal. According to the type and temperature range of TCXO, the standard range of typical stability of TCXO is less than (+0.5 ppm) to (+5 ppm).

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