Contents
What is VCXO oscillator?
A VCXO (voltage controlled crystal oscillator) is a crystal oscillator which includes a varactor diode and associated circuitry allowing the frequency to be changed by application of a voltage across that diode. Deviation – This is the amount of frequency change which results from changes in control voltage.
How does a MEMS oscillator work?
Microelectromechanical system oscillators (MEMS oscillators) are timing devices that generate highly stable reference frequencies, which can measure time. These reference frequencies may be used to sequence electronic systems, manage data transfer, define radio frequencies, and measure elapsed time.
What is an oscillator circuit?
An electronic oscillator is an electronic circuit that produces a periodic, oscillating electronic signal, often a sine wave or a square wave or a triangle wave. Oscillators convert direct current (DC) from a power supply to an alternating current (AC) signal.
What is MEMS timing?
What can a VCXO voltage controlled crystal oscillator do?
Voltage controlled crystal oscillators, VCXOs find uses in many RF circuits where the stability of a crystal oscillator or xtal oscillator is needed, but with the ability to pull or adjust them by a small amount. Using a VCXO enables high levels of stability combined with low levels of phase noise to be achieved.
Can a VCXO be pulled too far in a circuit?
However the frequency cannot be pulled too far, because the activity of the crystal reduces as the level of capacitance across the crystal increases. If it is necessary for the VCXO to be pulled over a large range, then an inductor can be incorporated into the circuit.
What makes the VCXO different from other diodes?
What makes the VCXO unique is the use of diodes to tune the frequency of the signal, a process known as “pulling” the frequency, which is measured in parts per million (ppm). This is usually done by placing varicap or varactor diodes on either side of the crystal.
How is the pullability of a VCXO determined?
For VCXO and VCTCXO, the recomended method of defining pullability. The value is relative to the specified nominal frequency, net of the device’s relative pull range and variations due to stability factors (such as temperature, aging, etc).