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Spread Spectrum Scene 

An Introduction to Oscillator Design

Oscillators are used in almost all Spread Spectrum, RF and wireless systems -- thus designers should know something about them. The "Beginner's Box" below graphically presents the most important design information concerning oscillators. In addition, we have included a variety of other links to help you learn more about this fascinating subject. Just click on a link below:

  Contents of This Page

Basic Oscillator Theory
Related Pages on SSS Online
Download Some Articles on Oscillator Design
Interesting Web Links on Oscillators
Article: NEL Spread Spectrum Technique Measurably Reduces EMI
Description of Oscillator Types
Oscillator Terminology & Considerations
Reference Books about Oscillators

  Beginners Box:
Some Very Basic Oscillator Theory:

Oscillators are a natural and expected part of the electronic scene. They occur in many, many applications and make possible circuits and subsystems that perform very useful functions. Oscillators occur sometimes even when we don't want them -- amplifiers can oscillate if stray feedback paths are present. Without oscillators we would probably live in a very dull world!

Oscillation occurs when an amplifier is furnished with a feedback path that satisfies two conditions:

  1. Amplitude Condition -- The cascaded gain and loss through the amplifier / feedback network must be greater than unity!

  2. Phase Condition -- The frequency of oscillation will be at the point where loop phase shift totals 360 (or zero) degrees!
In most oscillator circuits, oscillation builds up from zero when power is first applied, under linear circuit operation. However, limiting amplifier saturation and other non-linear effects end up keeping the oscillator's amplitude from building up indefinitely. Thus, oscillators are not the simplest devices in the world to accurately design, simulate or model. There is a real art to GOOD, STABLE oscillator design. As you learn more about oscillators you will certainly grow to appreciate them!

Please consult some of the references and links below for more information about oscillators.

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Related Topics on SSS Online:

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Articles to Download
Low Noise Oscillator Design Techniques Using a DLL-Based Frequency Multiplier for Wireless Applications, PhD Thesis by George Chien, Spring 2000, UCal-Berkeley

A Simple Analytic Method for Transistor Oscillator Design, by Andrei Grebennikov. — PDF Design note from Noble Publishing's archives. This straightforward mathematical technique helps optimize oscillator designs — .pdf file (1181K)

Designing Oscillators with Low 1/f Noise — Siemens Short App Note — .pdf file (12K)

Oscillator Design Techniques Allow High Frequency Application of Inverted Mesa Resonators — Saronix 8 page App Note — .pdf file (228K)

New Models Simulate RF Circuits Intusoft SPICE, 6 page App Note — .pdf file(96K)

Crystals and Oscillators — NEL 16 page App Note — .pdf file (165K)

ECL Oscillator Application Note — NEL one page App Note — .pdf file (6K)

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Interesting Web Information Links:

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NEL Spread Spectrum Technique Measurably Reduces EMI

NEL Frequency Controls, Inc. has introduced a Spread Spectrum technique designed to modulate the output of a single PLL, spreading the bandwidth of a synthesized clock and decreasing the peak amplitudes of its fundamental frequencies and harmonics.

Because FCC regulations on EMI change at speeds above 1 GHz, engineers require frequency control devices which provide both reliable clock performance and reduced emissions. The NEL Spread Spectrum technique reduces EMI for the primary clock source, thus also modulating all other signals being synchronized by the clock. By increasing the bandwidth to lower the power level at the center frequency, NEL's Spread Spectrum solution is capable of reducing measured EMI by as much as 12dB.

Ideally suited for use in computers, notebooks and other digital systems, the NEL Spread Spectrum technique reduces EMI without the need for more costly shielding or enclosures.

Crystal Oscillator Reduces EMI from Computers -- NEL three page App Note -- .pdf file -- (107K)

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Description of Oscillator Types
From Wenzel Associates, Inc.

  • (XO), non-compensated crystal oscillators.
  • (TCXO), temperature compensated crystal oscillators.
  • (OCXO), oven controlled crystal oscillators.
  • (VCXO), voltage controlled crystal oscillators.
  • other types.

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Oscillator Terminology and Considerations
From Wenzel Associates, Inc.

Wenzel Associates is a manufacturer of precision crystal oscillators and related radio frequency devices for the communications, navigation, military, and test equipment markets. In addition to components, they manufacture a variety of high performance instruments and subsystems. They have a very interesting website with lots of neat technical information. See some links below:

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Reference Books on Oscillator Design
Available for Purchase

Click on a Title Below for a Direct Link to Purchase


Oscillator Design and Computer Simulation, by Randall W. Rhea. Hardcover 1st edition (September 2000).


Oscillator Circuits, by Rudolf F. Graf. Paperback - 192 pages (March 1997).


Practical Oscillator Handbook, by Irving M. Gottlieb. Paperback - 292 pages (January 1997).


Mic & Mmic Amplifier and Oscillator Circuit Design (Artech House Microwave Library) , by Allen A. Sweet. Hardcover - 367 pages (April 1990).


The Design of Low Noise Oscillators, by Ali Hajimiri and Thomas H. Lee. Hardcover - 224 pages (February 28, 1999).


Solid-State Microwave Power Oscillator Design (Artech House Microwave Library) , by Eric L. Holzman & Ralston S. Robertson (Editors). Hardcover - 462 pages (December 1992).


High-Performance Oscillators and Oscillator Systems, by Jan R. Westra. Paperback (September 1998).


Analog Circuit Design : (X)Dsl and Other Communication Systems; Rf Most Models; Integrated Filters and Oscillators, by Willy Sansen, Johan H. Huijsing, Rudy J. Van De Plassche (Editors). Hardcover - 392 pages (October 1, 1999).


Theory of Oscillators, by A. A. Andronov, S. E. Khaikin, A. A. Vitt. Paperback - 815 pages (November 1987).


Linear Active Circuits: Design and Analysis, by William Rynone, Jr. Hardcover - 540 pages (May 1986).


Microwave Circuit Design Using Linear and Nonlinear Techniques , by George Vendelin, Anthony M. Pavio, Ulrich L. Rohde. Paperback - 784 pages Reprint edition (May 1992).

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Precision Frequency Control : Oscillators and Standards, by Eduard A. Gerber (Editor). Hardcover Vol 002 (June 1985).

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