Electronics World articles Popular Electronics articles QST articles Radio & TV News articles Radio-Craft articles Radio-Electronics articles Short Wave Craft articles Wireless World articles Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs LinkedIn Crosswords Engineering Humor Kirt's Cogitations RF Engineering Quizzes Notable Quotes Calculators Education Engineering Magazine Articles Engineering software RF Cafe Archives RF Cascade Workbook 2018 RF Symbols for Visio - Word Advertising RF Cafe Forums Magazine Sponsor RF Cafe RF Electronics Symbols for Visio RF Electronics Symbols for Office Word RF Electronics Stencils for Visio Sponsor Links Saturday Evening Post NEETS EW Radar Handbook Microwave Museum About RF Cafe Aegis Power Systems Anritsu Alliance Test Equipment Amplifier Solutions Anatech Electronics Axiom Test Equipment Berkeley Nucleonics Bittele Centric RF Conduct RF Copper Mountain Technologies Empower RF everything RF Exodus Advanced Communications Innovative Power Products ISOTEC KR Filters Lotus Systems PCB Directory Rigol RF Superstore San Francisco Circuits Reactel RFCT TotalTemp Technologies Triad RF Systems Windfreak Technologies Withwave LadyBug Technologies Wireless Telecom Group Sponsorship Rates RF Cafe Software Resources Vintage Magazines Thank you for visiting RF Cafe!
Lotus Communication Systems Modular RF Component Building Blocks - RF Cafe

Failed Harmonic Balance of Oscillator using ADS - RF Cafe Forums

RF Cafe Forums closed its virtual doors in 2010 mainly due to other social media platforms dominating public commenting venues. RF Cafe Forums began sometime around August of 2003 and was quite well-attended for many years. By 2010, Facebook and Twitter were overwhelmingly dominating online personal interaction, and RF Cafe Forums activity dropped off precipitously. Regardless, there are still lots of great posts in the archive that ware worth looking at. Below are the old forum threads, including responses to the original posts.

NOTICE: The original RF Cafe Forum is available again for reading, and the new RF Cafe Blog is an active board.

-- Amateur Radio

-- Anecdotes, Gripes, & Humor

-- Antennas

-- CAE, CAD, & Software

-- Circuits & Components

-- Employment & Interviews

-- Miscellany

-- Swap Shop

-- Systems

-- Test & Measurement

-- Webmaster


Post subject: Failed Harmonic Balance of Oscillator using ADS Posted: Fri Jul 18, 2008 10:54 am


Joined: Tue Feb 27, 2007 6:16 am

Posts: 46


I have managed to gain access to the use of the ADS simulator.

Below is an Oscillator I modified for my purposes.

Below is the results of the S parameter simulation. As you can see it appears to oscillate at 120MHz.

Unfortunately when I try and perform the Harmonic Balance Simulation (I wish to determine phase noise), the simulation fails.

Does anyone have any suggestions as to how I can correct the problem?



Regards, Darcy Randall, Perth, Western Australia



Post subject: Posted: Fri Jul 18, 2008 10:57 am


Joined: Tue Feb 27, 2007 6:16 am

Posts: 46

On a last note, referring to the results figure, whats the difference between the option of plotting analysis.sp1.s(1,1) and sp1.s(1,1)



Regards, Darcy Randall, Perth, Western Australia



Post subject: Posted: Fri Jul 18, 2008 4:33 pm


Joined: Tue Jul 08, 2008 7:15 pm

Posts: 11

Location: Boulder Colorado


It looks like you are trying to model a crystal oscillator. It can be difficult for simulators to converge when circuits have very high Q. This is because small steps in frequency can cause large jumps in voltage and current which gives simulators fits.

With the circuit shown, it looks like the crystal will be inductive at resonance, and will resonate with the two series caps. I would start by calculating an inductor that will resonate with caps, and see if simulator converges. Modify inductor to get desired frequency. Then insert series (Rm) with inductor, and see circuit has enough loop gain to sustain oscillation. You may need to change ratio of caps to improve margin. At this point, it will be likely your XO will at least fire up.

Good luck,

- Mark -

Posted  11/12/2012

Innovative Power Products Couplers
Exodus Advanced Communications Best in Class RF Amplifier SSPAs
RF Electronics Shapes, Stencils for Office, Visio by RF Cafe
KR Electronics (RF Filters) - RF Cafe
RIGOL Technologies (test equipment) - RF Cafe

Please Support RF Cafe by purchasing my  ridiculously low−priced products, all of which I created.

These Are Available for Free


About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024


    Kirt Blattenberger,


RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website: