Inside Frequency Control

Why is it important to choose the right crystal oscillator output signal?

The output signal types of crystal oscillators can provide different benefits and drawbacks depending on what you're trying to accomplish with your product. With that said, it's important to understand signal types to avoid as much attenuating and distorting of your clock signal as possible. You'll also want to be sure you're receiving more benefits than drawbacks from the signal to meet your specific design needs.

In a perfect world, a crystal oscillator would generate a signal that remains steady, consistent, and clear with no deviations, for as long as that signal needs to be transmitted. 

But in the real world, no crystal oscillator produces a 100% perfect signal. Even if the signal is very strong and clear, there will still be tiny, random fluctuations in its waveform. This phenomenon can be represented visually in the frequency domain as sidebands on either side of the carrier. These unwanted fluctuations are referred to as phase noise.

In the blog, we'll explain why you need to measure phase noise, what the methods are for measuring it, and 

What if we told you that specifying more electronic frequency control (EFC) than you need could actually be hurting your company's wallet? Well, it very well may be!

Paying attention to whether your supplier is using AT-cut or SC-cut crystals will help you save money in the long run when it comes to oscillators. In this article, we'll review the difference between these two types of cuts and the impacts of EFC pull. 

Frequency perturbations, also referred to as activity dips, can be difficult to spot in crystal oscillators. But a single perturbation can cause major problems in an application’s signal, including within GPS or missile systems.

Imagine launching a missile and then losing control of its navigation. Or getting a very inaccurate GPS velocity reading of an aircraft. These (and many other problems) can be caused by a failure to spot activity dips in crystals.

In this article, we'll help you  understand what frequency perturbations are and how to prevent them from occurring in crystal oscillators.

Quartz crystal oscillators are the high and mighty option for low phase noise and added frequency stability in circuit design. Yes, simple oscillators like those made with resistor-capacitor (RC) or inductor-capacitor (IC) resonators are fine for some circuits.

But if you're dealing with higher performance applications in the aerospace, military, and space industries, you're going to want a higher performance crystal oscillator that can maintain low phase noise and strong stability. Otherwise, you'll risk deviating from the very specific (and usually critical) center frequency selected for your design.

In this blog, we'll discuss how to measure low phase noise and how to maintain it in your applications.

One is definitely the loneliest number. So what's better, a single (OCXO) or double oven controlled crystal oscillator (DOCXO)?

One of the core challenges any RF engineer faces is maintaining frequency stability in crystal oscillators. In an ideal world, an oscillator would transmit at the desired frequency indefinitely and without deviation… but of course, we don’t live in an ideal world, and frequency drift is a real problem in many applications.

There are a number of factors that can cause an oscillator to deviate from the correct frequency, but frequency drift is not an insurmountable issue. There are various approaches engineers can take to improve stability. In this article, we'll discuss the best approaches to maintaining a high degree of stability your in crystal oscillators.

Will a crystal oscillator operate outside its specified temperature range? This is a common question and the short answer is: yes, but it's complicated.

If, for example, a crystal oscillator is specified over 0 to 60 °C, it will most likely perform without any issues over -40 to 85 °C. But it's possible that it will fall outside its specified stability. This may not matter if the application needs just a stable frequency rather than an accurate frequency.

RF engineers would love to get their hands on an ideal crystal oscillator circuit. That is, a quartz crystal oscillator that transmits at the designated frequency for the entire life of the device without any frequency deviation. Unfortunately, that ideal circuit world is a mathematical fantasy.

There are many factors that contribute to quartz oscillator stability and frequency drift issues. To prevent these problems as much as possible, it's important to have a firm understanding of precise frequency stability. This will give you the tools to keep your applications performing optimally. But there's another problem...

There are many different types of crystal oscillators. OCXOs, TCXOs, and VCXOs are some of the most common types of oscillators. Each have their own advantages and disadvantages. One of the core responsibilities of a lead RF engineer is to pick the oscillators that are an optimal fit for their designs and applications.

If you want to be able to fine-tune your frequency source and get a stable, dependable signal, a voltage-controlled crystal oscillator (VCXO) might be just the solution you’re looking for. Let’s explore the benefits of the VCXO and how you can put them to work in your designs.