Causes and Solutions of Abnormal Frequency of Epson Crystal Oscillation
Release date:2018-12-21 Author:Guan Shuo Click:
When the temperature characteristic of Epson crystal oscillation frequency is abnormal, the following reasons should be considered: excessive driving power, abnormal characteristics of crystal resonator and temperature characteristic of oscillating circuit elements. So how should we deal with it?
1. Driving power is too high
If the driving power exceeds the value specified in the specifications of crystal resonators, the abnormal temperature characteristics of the oscillation frequency can be determined. This is called "jump" or "exciting jump". This phenomenon may be caused by excessive driving power.
If the driving power exceeds the value specified in the specifications of crystal resonators, the abnormal temperature characteristics of the oscillation frequency can be determined.
If it is an exciting jump, the temperature characteristics of the oscillation frequency may be distorted.
In order to avoid exciting jump, it is necessary to reduce the driving power.
Measure 1: Reduce external load capacitance
When the external load capacitance is reduced, the impedance of the oscillator circuit will increase and the actual driving power will decrease.
In this way, the actual oscillation frequency will increase due to the reduction of load capacitance.
Therefore, it is better to check whether the actual oscillation frequency is within the desired frequency range.
Measure 2: Increase the Damping Resistance
With the increase of damped electrons, the output amplitude of the inverted-phase amplifier will decrease, and the actual driving power will also decrease.
With this adjustment, the oscillation amplitude will also be reduced. Therefore, it is better to check whether the oscillation margin is more than five times.
In addition, it should be noted that the oscillation amplitude should not become too small.
2. Abnormal characteristics of crystal resonators
Please check whether the frequency-temperature specifications contain the temperature characteristics of the frequency of the loaded crystal resonator. Need network analyzer or impedance analyzer to check. If the characteristics of crystal resonators are normal, check the temperature characteristics of oscillating circuit elements.
3. Effect of Temperature Characteristics of Oscillating Circuit Components
If the change of temperature results in the change of external load capacitance or parasitic capacitance, the oscillation frequency will shift. Please check their temperature characteristics.