Voltage-Controlled Crystal Oscillators (VCXOs)Voltage-controlled crystal oscillators (VCXOs) are a type of crystal oscillator that is used to generate a precise, stable frequency for use in electronic circuits and systems. A crystal oscillator is a type of electronic oscillator that uses the mechanical resonance of a crystal to generate a precise frequency. In a VCXO, the output frequency of the oscillator can be controlled by applying a voltage to the crystal, allowing for fine-tuning of the frequency. VCXOs are commonly used in applications where a precise, stable frequency is required, such as in telecommunications systems and frequency synthesisers.