Why is there no signal output from the crystal?

A.

If there is no signal output across the crystal terminals using an oscilloscope or spectrum analyzer, please follow these troubleshooting steps:

1. Check Voltage at Input and Output: Ensure that there is voltage output at the input terminal (Xin) and output terminal (Xout) of the crystal, and that it meets the specifications required by the IC.
2. Remove the Crystal and Test: Remove the crystal and use a professional testing instrument to check whether its parameters meet the specifications. You can also send it to your supplier for testing.
3. Verify Crystal Quality: If the crystal is confirmed to be functional but still does not oscillate, the issue may be due to insufficient negative resistance in the oscillation loop. Generally, negative resistance should be greater than five times of ESR for optimal performance.

∣−R∣=Re+VR, Negative resistance margin is defined as: Gain Margin=∣−R∣/ESRmax ≥ 5

1. Check Drive Level: If the drive level is too high, it can cause unstable frequency, amplitude, and higher resistance, or if the drive level is too low, it may also stop oscillation.
2. Adjust External Components: If the problem still cannot be solved after adjusting parameters through external components, please contact the field application engineer of the crystal or IC manufacturer for further assistance.