packaged crystal oscillators (SPXO)
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 ±
Temperature compensated crystal oscillators (TCXO)
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
With TCXO, temperature compensating circuits are built-in to get excellent
temperature characteristics over a wide temperature range.
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
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
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)
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.