about Oscillator

1. SPXO Simple Packaged Crystal Oscillator

SPXO delivers excellent frequency stability without the necessity of temperature compensation and frequency control.
Housing crystal units that consist of AT or BT cut fundamental or overtone and their oscillation circuit in the same package, our crystal clock oscillators are designed and manufactured to provide a stable output of signals when the set voltage is applied.
Generally, when customers buy crystal units and use them in their oscillation circuits, they first need to provide analog settings prior to the installation. These include the settings of load capacitance, oscillation allowance, and variations in characteristics due to temperature changes. With Epson's crystal clock oscillators, these settings are already provided by us,so their output signals can directly control TTL and CMOS ICs. This shortens design processes for customers and contributes to standardizing parts to be used. Our crystal clock oscillators also feature a VCXO function and a Try-state function. The VCXO function enables control of output frequencies with external control voltage, whereas the output enable feature maintains the output terminals at high impedance levels by outputting signals with control signals while the power is supplied.

Type of XO

Crystal osillator Crystal oscillator that has the output function of 1 frequency XO standard(MHz)
XO extended temperature
XO differential
XO standard(32kHz)
Programmable Crystal oscillator that the customer can freely set up output frequency XO quick delivery
(Programmable type)
Spread Spectrum Crystal oscillator that has the SS function as for the EMI measure XO quick delivery
SG-9000 series
Low_Jitter Crystal oscillator that included SAW resonator for low jitter XO low jitter
High-stability Crystal oscillator that is designed to high accuracy in SPXO HG-2150CA
Multi-output Crystal oscillator that outputs 2 or more pieces of frequency simultaneously XO low jitter
MG-xxxx series
Multi-output Crystal oscillator that outputs 2 or more pieces of frequency simultaneously XO selectable

2. TCXO Temperature Compensated Crystal Oscillator

A TCXO is a crystal oscillator with a temperature-sensitive reactance circuit in its oscillation loop to compensate the frequency-temperature characteristics inherent to the crystal unit. Epson's are classified into two types. One is a Direct-Type TCXO with a temperature compensation circuit built into the oscillation loop. The other is an Indirect-Type TCXO with a temperature compensation circuit outside the oscillation loop, in which the oscillation frequency is therefore indirectly controlled. Circuit diagrams of the two types of TCXO are shown in Figs.1 and 2.

EPSON TCXO products
TCXO standard
TCXO for GPS
TCXO for Network


Circuit diagrams


Fig.1 Simplified schema of the indirect compensation TCXO
Fig.1 Simplified schema of the indirect compensation TCXO


Fig.2 Simplified schema of the direct compensation TCXO
Fig.2 Simplified schema of the direct compensation TCXO


3. VCXO Voltage Controlled Crystal Oscillator

A VCXO (Voltage Controlled Crystal Oscillator) is a crystal oscillator the output frequency of which is controlled by adding an external control voltage via a frequency control input on a variable capacitance component such as a varactor diode connected in parallel to a load capacitance (CL). Epson VCXOs are divided into two types according to Voltage-Frequency (V-F) characteristic slopes depending on the AFC (Automatic Frequency Control) input configuration of the VCXO. One is a VCXO with a positive V-F slope and the other is a VCXO with a negative V-F slope. Please note that the input voltage of a control circuit will vary according to the individual type, as shown in Figs. 3 and 4. Epson's VCXOs are capable of either, depending on the customer's preference. Epson's VCXOs have been increasingly used for broader applications such as slave oscillators in phased-lock loops, or frequency modulators.
Among the above types, a VCXO combined with a TCXO is called a VC-TCXO , respectively. These components have the merit of delicately controlling their output frequency electrically.

EPSON VCXO products
VCXO standard
VCXO low phase noise

Circuit diagrams

Fig.3 Control voltage characteristics of VCXO(positive slope)
Fig.3 Control voltage characteristics of VCXO(positive slope)

Fig.4 Control voltage characteristics of VCXO(negative slope)
Fig.4 Control voltage characteristics of VCXO(negative slope)


4. OCXO Oven Controlled Crystal Oscillator

OCXO exhibits an extremely high frequency stability by housing the crystal unit or both the crystal unit and the oscillation circuit in a constant-temperature oven. The OCXO with SC-cut (Stress Compensation-cut) crystal unit that is introduced in this catalog has been more commonly used in recent years instead of the traditional OCXO with AT-cut crystal unit. Epson offers advanced OCXOs that maximize the advantage of the SC-cut crystal unit to meet the needs of the marketplace, e.g.
(1) high frequency stability in a compact design
(2) quick start-up
(3) high resistance to vibrations induced by cooling fans
(4) excellent C/N characteristics, etc.
For even higher frequency stability, Epson offers the Double-Oven type that uses a two-layered constant-temperature oven.
Among the above types a VCXO combined with an OCXO is called a VC-OCXO, respectively. These components have the merit of delicately controlling their output frequency electrically.

5. Rubidium Oscillator

Rb-OSC (Rubidium Oscillator) :

Extremely stable oscillator using atomic resonance of Rubidium
Controlled by the microwave-transition frequency of Rb87 atoms in its ground state of energy.

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