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Simple packaged crystal oscillators (SPXO)

This family of products are simple crystal oscillators with no temperature compensation and are used in relatively low precision applications such as digital clocks. The main applications are microprocessors. computers and various switching systems.

The frequency vs. Temperature stability is essentially influenced by the temperature characteristics of crystal units used to those of the oscillation circuit. The frequency stability range between ±
7 ppm to
± 150 ppm depending on the operating temperature range. At a reduced temperature range (0°C to 50°C) corresponds generally ( ± 7 ppm to ± 15 ppm) than at a military temperature range (-55°C to +125°C) for which the stability is ± 50ppm.

 

Temperature compensated crystal oscillators (TCXO)

The temperature characteristics of crystal oscillators are, for the most part, dependent upon those of crystal units used which are generally expressed by cubic curves(AT-cut). Obtaining superlative teperature kept constant by means of a constant temperature oven.
With TCXO, temperature compensating circuits are built-in to get excellent temperature characteristics over a wide temperature range.
The temperature compensating circuit performs the function of compensating the temperature detecting elements and resistances. That is why the resultant temperature characteristics differ depending upon the combination of compensation circuits or the sepcified temperature range. In general, temperature characteristics are expressed 3rd to 5th curves. TCXO feature exellent temperature characteristics, low power consumption, light weight, compactness and fast warm-up, and are ideally suited for various communications
equipment (mobile telephones, car telephones, MCA, cordless telephones, microwave communications equipment and satellite communication system) and measuring instruments (frequency counters, frequency synthesizers, etc.) as standard oscillators.




Voltage controlled crystal oscillators (VCXO)

With VCXO, the connection of a variable capacitance diode with a crystal unit in series causes the diode capacitance to be changed in accordance with the voltage applied for frequency control, thus pulling frequency corresponding to the load capacitance characteristics of crystal units. Our VCXO feature superlative linearity realized by the proper combination of the applied voltage and capacitance chracteristics of a variable capacitance diode with the load capacitance and oscillation frequency characteristics of crystal units.
The temperature characteristics of
VCXO are the same as those of SPXO and are ideally suited for PLL, AFC, circuit sevo system, FM modulator, sweep generator, etc.




Oven controlled crystal oscillators (OCXO)

The OCXO is an oscillator which is temperature controlled (Ovenized crystal controlled oscillator). This type of oscillator has a temperature controlling circuit to maintain the crystal and key components at a constant temperature.

  
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