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What is the function of the capacitors in the oscillator circuit?
A capacitor can possess spring-like qualities in an oscillator circuit. In the image example, a capacitor acts to influence the biasing voltage at the npn transistor’s base. The resistance values of the voltage-divider resistors and the capacitance value of the capacitor together control the oscillatory frequency.
Do oscillators need capacitors?
Most resonators require load capacitors to provide phase shift and sustain oscillation. This ensures that the resonator and oscillator circuit are matched, eliminating the need for external capacitors to tune the resonate frequency.
Why we are using crystal oscillator?
In general, we know that, crystal oscillators are used in the microprocessors and microcontrollers for providing the clock signals. This crystal oscillator is used to generate clock pulses required for the synchronization of all the internal operations.
How are capacitors used to make a crystal oscillate?
The capacitors are there to resonate with the crystal inductance and cause the crystal to oscillate on its fundamental parallel-resonant mode.
Can a crystal oscillator be connected to an inductor?
Yes, in some crystal oscillator circuits, you have a first shunt capacitor (bottom end grounded), then the crystal connected in series to a second shunt capacitor, similarly grounded. The crystal, at a frequency just slightly above its “series resonant” frequency, looks like an inductor of a certain value.
What are the two types of crystal oscillators?
There are two kinds of crystal oscillators. One operates at what is called the “series resonance” of the crystal. This resonance is the frequency at which the (AC) impedance between the pins of the crystal is almost zero.
What is the ppm of a shunt capacitor?
Essentially, the load capacitance of the crystal, C L, is set equal to the combination of the capacitors you’re adding and the shunt capacitance of the crystal, so The ppm figures specify the (in)accuracy of the crystal (when properly used): 5 ppm is 5 parts per million.