Key electrical parameters of VCXO and examples

  • 08 February, 2024

Voltage-Controlled Crystal Oscillators (VCXOs) have several key specifications that define their performance. Here are some examples for a hypothetical VCXO:

1. Frequency Range: 155.52 MHz – This is the nominal frequency at which the VCXO operates.

2. Voltage Control Range (VCR): 0 - 3.3 V – This is the range of control voltage over which the VCXO can vary its frequency.

3. Frequency Deviation/Pull Range: ±100 ppm – This specifies how much the output frequency can be "pulled" or varied from its nominal value with the maximum control voltage.

4.Linearity: <1% – Indicates that the frequency deviation is linear to the control voltage change within 1% error.

5. Temperature Stability: ±2 ppm from -40°C to 85°C – Shows how stable the frequency is over a specified temperature range.

6. Supply Voltage: 3.3 VDC – This is the required voltage to power the VCXO.

7. Output Waveform: LVPECL, LVDS, or CMOS – Specifies the type of signal output from the VCXO.

8. Aging: ±1 ppm per year – Indicates the expected change in frequency due to aging after one year.

9. Power Consumption: 25 mW – The typical power usage of the VCXO.

10. Phase Noise: -145 dBc/Hz at 10 kHz offset – This is a measure of the frequency stability in the short term, measured at a specified offset from the carrier frequency.

11. Harmonic Distortion: -20 dBc – This represents the strength of the harmonic frequencies compared to the fundamental frequency.

12. Duty Cycle: 50% ±5% – This specifies the symmetry of the output waveform's high and low phases.

These specifications can be found in the datasheet of a VCXO and are crucial for engineers when they are integrating the VCXO into a system, ensuring it meets the required performance and compatibility standards.

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