Welcome to the Crystal Oscillator Professor
This blog is about the nuts and bolts of time and frequency control, and especially about the details of crystal oscillators, which are particularly fascinating devices. This blog will explore how timing systems using crystal oscillators work, and how to use, specify and troubleshoot crystal oscillators, as well as tracking and discussing the exciting new developments in the field.
The Importance of Crystal Mounting Structure
Quartz is relatively abundant in nature and easy to grow in a very pure form. What sets it apart from other piezoelectric crystals is that it can be made to vibrate in very controlled and stable ways. Thus, a properly fashioned quartz resonator can act as an ultra-stable mechanical frequency source that can be coupled to an electronic oscillator circuit.
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Phase Noise, Jitter and Allan Deviation – Comparisons and Distinctions
Precision clocks need to maintain as pure a signal as possible, over very short periods of time. In the frequency domain, this is referred to as Phase Noise. In the time domain it is measured as Jitter.
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How are Oscillators Tested for Radiation?
All of these space environments have unique radiation environments. There are no exact ways to duplicate the radiation exposure of each space environment, rather the best that can be done is to create analog radiation environments that can simulate the actual environments in space.
Testing of Precision Quartz Crystal Oscillators
Quartz is relatively abundant in nature and easy to grow in a very pure form. What sets it apart from other piezoelectric crystals is that it can be made to vibrate in very controlled and stable ways. Thus, a properly fashioned quartz resonator can act as an ultra-stable mechanical frequency source that can be coupled to an electronic oscillator circuit.
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How to Manufacture Precision Quartz Crystals
It takes a precise and time-consuming process to produce baseplated crystal disks tailored to precise frequencies
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Activity Dips and How to Avoid Them
Commercial grade quartz crystal oscillators can sometimes exhibit problems known as “activity dips” that occur only at very specific temperatures. If you never happen to operate at exactly the problem temperature, you will never see the problem. But what is an activity dip? It’s a relatively sudden increase in the crystal’s resistance, (a perturbation) in the quartz crystal’s series resistance and frequency characteristics over temperature. Generally, activity dips are caused by an interfering mode of vibration (coupled mode) in the quartz crystal. A coupled mode bleeds energy from the main mode if and when its frequency coincides with the frequency…
