Crystal have different requirements and characteristics, points into the following categories: ordinary crystal, Wen Bujing oscillator, voltage controlled crystal, crystal temperature. During the test and use for DC power supply should not affect the accuracy of the ripple content, AC voltage should be no transient process. Apparatus for testing with sufficient accuracy, reasonable arrangement of the test line, and the external circuit to minimize the effect of crystal index. The following will one by one to answer your questions related to crystal related knowledge.
Crystal: crystal oscillator, its function is to produce original clock frequency, the frequency of the frequency generator is enlarged or reduced after a computer in a variety of different bus frequency. To the sound card as an example, to realize the simulation of signal 44.1kHz or 48kHz sampling, frequency generator must provide a 44.1kHz or 48kHz clock frequency. If you need the two audio support both words, sound card requires two crystal. But the entertainment class sound card in order to reduce the cost, usually using SRC output sampling frequency is fixed in the 48kHz, but SRC will bring damage to sound, and now the entertainment class sound card are not a good solution to this problem. Crystal crystal resonator is commonly called, is a kind of electromechanical devices, power loss is very small quartz crystal by precision cutting grinding and coating on the electrode welding wire. The crystal has a very important characteristic, if it is energized, it produces a mechanical oscillation, conversely, if given a mechanical force, it will generate electricity, the characteristic that electrical and mechanical effect. They have a very important feature, the oscillation frequency and their shapes, materials, and other closely related to cutting direction. As the quartz crystal of extremely stable chemical properties, thermal expansion coefficient is very small, the oscillation frequency is very stable, due to the control of geometrical size can be very precise, therefore, the resonant frequency is very accurate. According to the quartz crystal in the electrical and mechanical effect, we can make it equivalent to an electromagnetic oscillation circuit, the resonance circuit. Their electrical and mechanical effect is machine - electricity - machine - electricity. The changing. By inductance and capacitance, resonant circuit consisting of the electric - magnetic field is changing. In the application of circuit is actually regard it as a high Q value of the magnetic resonance loop. As the quartz crystal loss is very small, the Q value is very high, do the oscillator is used, can produce very stable oscillations, as a filter, can achieve very stable and steep band-pass or band-stop curve.
No comments:
Post a Comment