In the design of passive crystal, frequently encountered values of the size of the load capacitance CL, the design and improve the accuracy of the crystal, the crystal KHz passive stop, the accuracy of the tuning fork crystal resonator oscillator drift and accuracy and at a high temperature passive questions whether the accuracy of worries accuracy equal to low temperature and so on.
Passive Crystal whether oscillator (KHz and including MHz) can be directly referred to by such specification value CL to design? If not, what is the value of experience in the design of reference?
A: Not directly, it is recommended CL value -2PF or 3PF, then multiplied by two.
All capacitors equivalent to the crystal passive crystal oscillator (KHz and including MHz) load capacitance CL. The actual measurement should?
A: probe careful not to use an oscilloscope, pen input and output multimeter test tool directly detect the crystal oscillator, because oscilloscope probes, multimeter pen parasitic capacitance characteristics, the test time. The equivalent capacitance of the entire load will change, measurement data will be inaccurate. At the same time, ESR crystals will change, even crystal oscillator will stop.
solution:
Hall induction test principle using the crystal oscillator output waveform, to convert AC variable magnetic field and indirect amplification, shaping. If there is no equipment, you can ask the manufacturer to help make the resistance - capacitance matching test, while some big imported crystal oscillator vendors can provide free of resistance - capacitance matching test.
MHz passive SMD crystal operating temperature is generally in the industrial nominally -40 ~ 85 ~ C. Car rules crystal and military products will use C crystal MHz passive temperature -40 ~ 105 ~ C -40 ~~ 125 ~ Crystal whether accuracy is the same as when 85 ~ C?
A: The difference is, MHz crystal oscillator in the high-temperature region 105 ~ 125 ~ C the slope of the sine wave is large, presenting divergent sine wave oscillation at this time is generally 30 ~ 50ppm accuracy, the low--40 ~ 85 ~ C range up to 10ppm. Industrial grade nominal temperature of the crystal oscillator can operate at high temperatures, but not high temperature performance testing, error precision can be increased to 30ppm ~ 50ppm.
What KHZ passive tuning fork crystal oscillator circuit special considerations in the design is?
A: In order to avoid resonance, low frequency vibration to be away from the source such as a motor, which may lead to the prongs severely broken, does not work.
32.768KHz passive crystal accuracy inverted parabolic temperature profile wherein the temperature of the central axis 25, the theoretical accuracy of 0 ppm, but the actual design requirements parabolic move 5-7 ppm. Thus, both positive and negative in the entire temperature range, which can offset some accuracy error.
Reproduced in: https: //www.cnblogs.com/duwenqidu/p/11044432.html