about Oscillator
1. SPXO Simple Packaged Crystal Oscillator
SPXO (Simple Packaged Crystal Oscillator) delivers excellent frequency stability without the necessity of temperature compensation and frequency control. Housed in the same package, the crystal unit and oscillation circuit are designed and manufactured to provide a stable signal output when a specified power supply voltage is applied. Generally, when a customer purchases a crystal unit and designs an oscillation circuit for use, analog design elements are required, such as specifying the load capacitance of the crystal unit, securing the oscillation allowance, and maintaining characteristics during temperature changes, etc. Epson’s crystal clock oscillators helps reduce design man-hours and selection because we design and manufacture these analog parts to work synergistically, with output signals available in a wide variety of types, such as CMOS, LV-PECL, LVDS and HCSL. Other functions include an output enable function that stops signal output while supplying power with a control signal for faster start-up time, and a standby function that stops the oscillator circuit and signal output to suppress current consumption while the circuit is stopped. Epson also offers other various types of SPXOs depending on the functions and features required.
Type of XO
Crystal osillator | Crystal oscillator that has the output function of 1 frequency |
Programmable | Crystal oscillator that the customer can freely set up output frequency |
Spread Spectrum | Crystal oscillator that has the SS function as for the EMI measure |
Low_Jitter | Crystal oscillator that included SAW resonator for low jitter |
High-stability | Crystal oscillator that is designed to high accuracy in SPXO |
Multi-output | Crystal oscillator that outputs 2 or more pieces of frequency simultaneously |
Multi-output | Crystal oscillator that outputs 2 or more pieces of frequency simultaneously |
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.
3. VCXO Voltage Controlled Crystal Oscillator
A VCXO (Voltage Controlled Crystal Oscillator) is a crystal oscillator in which the output frequency is controlled an external control voltage. This is achieved via a frequency control input by a variable capacitance component, such as a varactor diode, connected in parallel to a load capacitance (CL). As shown in Figure 3, the control voltage vs. frequency characteristic of this VCXO generally has a positive slope (the frequency increases as the voltage increases), and the control voltage is applied as shown in the configuration circuit example. VCXOs are increasingly being used as slave oscillators in phase-locked loops (PLL) systems and as frequency modulators. Crystal oscillators that combine a VCXO and a TCXO are called VC-TCXOs. They offer the advantage of fine tuning the outputfrequency electrically.
Circuit diagrams
Fig.1 Control voltage characteristics of VCXO(positive slope)