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Inside Frequency Control

The Secret to Maintaining Low Phase Noise in Oscillator Circuits

Posted by Rob Rutkowski on Feb 20, 2020 9:06:00 AM

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

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Topics: crystal oscillators, RF Technology, Integrated RF

Ultimate Guide to Understanding Phase Noise

Posted by Bliley Technologies on Feb 20, 2020 9:00:00 AM


Maintaining strong frequency stability in electronic RF circuits by eliminating phase noise is important in many high-end communication applications. This is especially true for precise targeting in radar systems and spectral purity in other communication systems.

Let's take a deep dive into exactly what phase noise and jitter mean. This will help give you a better idea as to why reducing a system's phase noise is significant.

What Is Phase Noise?

Phase Noise  is represented in the frequency domain of a waveform and consists of rapid, short-term, random fluctuations in the phase (frequency). This is caused by time domain instabilities (jitter).
 
Be sure not to confuse phase noise with Jitter. Jitter is a method of describing the stability of an oscillator in the Time Domain. It combines all the noise sources together and shows their effect with respect to time.

In the simplest terms, phase noise describes the stability of an oscillator in the Frequency Domain, while jitter describes stability in the Time Domain.

A Simple 5-Step Path to Understanding Phase Noise

To build an in-depth understanding of phase noise, try using this simple 5 step process. Once you understand the 5 steps, you'll understand what makes phase noise...well... phase noise! 
 
 
"How does Spectral Density connected to Phase Noise in the 5 step process?" you ask? Here's some more details on each step.

Step 1: Spectral Density

Spectral Density is a measure of a signal's power intensity in the frequency domain.  The spectral density provides a useful way to characterize the amplitude versus frequency content of a random signal.

Step 2: When plotting each spectral density point at varied frequency intervals of your choosing (In this case every 1Hz), you're left with a graph that looks like this:

Step 2: Signal Power Density

You are now looking at what is known as the Signal Power Density of the noise. 

Now focus only on the upper sideband of the graph from fstart to fstop, this is called the "Single Side Band".

Step 3: Noise Power Density

We can now refer to the plotted part of the single side band as noise (Anything above the nominal oscillator frequency (Fosc) and not harmonically related can be considered phase noise). The technical term for this part of our graph is Noise Power Density (Step 3). We measure noise power density in dBW (LOG(Watts)) at this point because of the large range which we are looking. 

Step 4: SSB Noise Density

When we combine the single side band and Noise Power Density, we are actually measuring what's called SSB (Single Side Band) Noise Density

Step 5: Phase Noise

Finally, we can look at this in the time domain and we see a "jittery" waveform (see graph), we are looking at "jitter". Because the jitter is much smaller than one complete period (see graph), we can say it is caused by "Phase Fluctuations" (instead of frequency fluctuations). Since these fluctuations are noise, it's actually  phase noise.
 
So...
SSB Noise Density = Phase Noise
...and that's where phase noise comes from! Easy, right?

What Causes Phase Noise?

Phase noise in higher-end applications (such as radar communications, military communications, and space & satcom communications) is typically caused by
  • High vibrations
  • Micro vibrations
  • g forces and acceleration sensitivity
Using an anti-vibration, g-sensitivity crystal oscillator is the best way to eliminate phase noise from all of these potential sources.
 
Here are some common sources of phase noise in crystal oscillators.
 
Random Noise Sources:
Related: Causes and solutions for phase noise in high-end radar and communication systems.

What's Next? Learn How to Achieve Low Phase Noise...

Achieving low phase noise in a crystal oscillator is critical to achieving high-performance. Therefore, it's important to understand an in-depth look at phase noise. Instantly download our free visual guide to the impact of phase noise on various applications.
 
Now that you know all about phase noise and jitter, you might find it useful to learn about the  best output signal type in your oscillators.
Download our visual guide to the effects of phase noise
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Topics: engineering, crystal oscillators

5 Best Benchtop Digital Multimeters (2020)

Posted by Tommy Reed on Feb 4, 2020 11:21:00 PM

Go into any electronics lab and you will undoubtably see a bench top multimeter.  The humble benchtop digital multimeter is a staple of any lane and is one of the most fundamental and highly used pieces of test equipment for electronic design. 

**Disclosure: This post contains affiliate links at no additional cost to you.

As the name implies, the digital multimeter is useful for a wide range of measurements and tests.  Bench top digital multimeters, or DMMs, can be used to to make the basic (Ohm’s Law) measurements:

  • Measure resistance
  • Measure voltage
  • Measure current
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Topics: engineering, General Topics, Engineering Equiptment

10 Popular Software Defined Radios (SDRs) of 2020

Posted by Bliley Technologies on Feb 4, 2020 11:19:00 PM

Back in 2016, we wrote one of our most popular posts covering 12 popular Software Defined Radios or SDRs.  While the previous post still holds some extremely valuable information, a lot has changed in 3 years... especially the technology related to SDRs.  So we thought it was time for an update.

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Topics: RF Technology, general

5 Great Engineering Laptops (Plus Free CAD Tool Guide)

Posted by Bliley Technologies on Feb 4, 2020 11:17:00 PM

Finding the Best Performing Engineering Laptop

Our engineering team at Bliley is growing, which is great, but it also introduces some new challenges for small business like ours... finding the best performing engineering laptops for our engineers.

We want to give our engineers the best tools available and create an environment where they can be their most innovative and do the best work of their careers.  Of course, a key to this whole equation is the technology they use day-to-day to get those next generations products designed. We recently kicked off a search for the best laptops that are perfect for engineering workloads. As you can probably imagine, the ideal laptop for an engineer needs to have great compute and graphics power.

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Topics: engineering, General Topics, general, Engineering Equiptment

6 Great Power Supply Options for Your Electronics Lab

Posted by Tommy Reed on Feb 4, 2020 11:16:00 PM

Have you noticed that your electronics lab could use a little upgrade from the 1970s to the present? If so, you've come to the right place. A reliable DC power supply is often considered a requirement in many of today's electronics labs. We wanted to share a few great power supply options to help you take your outdated power supply equipment further!

*This post contains affiliate links in which we will receive a small commission at no additional cost to you. 

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Topics: General Topics

Top 18 CAD Tools for RF and Microwave Design Engineers

Posted by Bliley Technologies on Feb 4, 2020 4:17:00 PM

RF and Microwave Design can be ENJOYABLE...

Don't believe me? Many of us already know how designing can easily become extremely long, boring, and tedious. This is especially true for all you RF and Microwave Design Engineers!

Spending hours upon hours designing, finding problems, fixing problems, then repeating the process all over again...It all can become so mentally draining.

Am I bringing back bad memories? Sorry, time for the good news...

So how can you make the long and tedious design process easy (and possibly even enjoyable)? 

You guessed it... Automation and design tools are key. 

Having some great CAD tools on your side can release a significant burden off your back. These tools can save you time and dramatically increase your productivity. Our Top 4 Productivity and collaboration tools will help skyrocket your productivity even further.

Today, we thought we'd help you out by sharing these 18 CAD design tools that can lead to a more simple & enjoyable design session.

**Related Post: Check out our picks for the 5 best laptops for engineers.**

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Topics: engineering, General Topics, general

5 Best Waveform Signal Generators in 2020

Posted by Rob Rutkowski on Feb 4, 2020 2:13:00 PM

I have a feeling you're in need of some new test equipment... a new signal generator to be exact. If so, you've come to the right place. Maybe your current signal generator is outdated. Or maybe you're looking for your first one (in which case we'd be honored). 

No matter the reason, we wanted to share with you the best selection of waveform signal generators on the market today to help you make the best purchase based on your needs.

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Topics: General Topics, Engineering Equiptment

12 Engineering Thought Leaders You Should Follow On Twitter

Posted by Bliley Technologies on Feb 4, 2020 1:05:00 PM
 
Twitter has become a great way to keep track of current events, find out what's trending, and see what other people are talking about.  Engineers have been using Twitter since the very beginning to connect and share relevant content.  There are few recognized thought leaders that have amassed followers by the thousands.  They've got some epic engineering content that we think could help inspire, challenge, and inform even the most seasoned engineers.

Without further adu, here is our list of engineering thought leaders that you should be following on Twitter.

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Topics: engineering

5 Simple Steps for Truly Effective Design Reviews

Posted by Bliley Technologies on Feb 4, 2020 11:30:00 AM

As electronics and RF systems have become increasingly complex, the need to catch and fix errors during the design phase of a project has become increasingly important.

Catching an error during the design phase is orders of magnitude less expensive to fix than catching it during the manufacturing or test phases.

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Topics: engineering, general