Crystal Oscillator Circuit Design

Of the frequency determined by the resistor and external capacitor.

Crystal oscillator circuit design.

This tutorial explains considerations to be addressed in a design of a simple crystal oscillator using at cut crystals. References and additional reading are listed below. These types of oscillator is practically invariably of the l c variety for functioning frequencies of a few hundred khz and above. It can be used in the normal clock circuit.

A crystal oscillator is obviously designed to offer high firmness at a single frequency and is useless if a tuneable wide range oscillator is needed. In this type of crystal oscillator design the filter consists of the crystal s equivalent model and the external load capacitors. Ever wonder what goes in to the design of a crystal oscillator. It will create an electrical signal with a given frequency.

There s no need for capacitors in the feedback loop for this type of circuit. The exact frequency at which an oscillator will operate is dependent on the loop phase angle shifts within the oscillator circuit. The design of a crystal oscillator is very similar to the design of the colpitts oscillator we looked at in the previous tutorial except that the lc tank circuit that provides the feedback oscillations has been replaced by a quartz crystal as shown below. Topics include load capacitance negative resistance startup time drive level dependency crystal aging and spurious modes.

A crystal oscillator is an electronic oscillator circuit that is used for the mechanical resonance of a vibrating crystal of piezoelectric material. A series circuit crystal oscillator uses a crystal that s designed to operate at its natural resonant frequency. Figure 2 4 shows the maximum drive power that can be put into a crystal without excessive heating and frequency shift in the crystal fig ure 2 5 shows the maximum permissible drive voltage across the crystal at exact series resonance. We ll examine the operational theory of crystal oscillators and design a discrete pierce crystal oscillator suitable for use as a local oscillator in an hf receiver.

Series resonant oscillator circuits are fairly basic and are typically used because of their small component count. 200 000 r is the largest single factor in oscillator design and dominates the design of every oscillator circuit. It consists of ic 4060 and ic 4013 the ic 4060 single acting oscillator and counter. Changes in the phase angle will result in a change in the output frequency.