The Designer's Guide Community
Forum
Welcome, Guest. Please Login or Register. Please follow the Forum guidelines.
Oct 21st, 2021, 1:32pm
Pages: 1
Send Topic Print
Loaded quality factor of voltage control oscillator (Read 362 times)
transign
New Member
*
Offline



Posts: 1

Loaded quality factor of voltage control oscillator
Nov 27th, 2020, 10:53pm
 
Hello,

How can I calculate in virtuoso the loaded quality factor of the VCO's main tank? Is there a specific test bench that I could use? Should I add only the parasitics of active devices?

Thanks a lot!
Back to top
 
 
View Profile   IP Logged
Horror Vacui
Senior Member
****
Offline



Posts: 113
Dresden, Germany
Re: Loaded quality factor of voltage control oscillator
Reply #1 - Mar 27th, 2021, 5:30am
 
It requires the presence of the active devices -- like cross-coupled pair, or the amp in Colplitts - in its working condition. Therefore the circuit has to oscillate during the measurement1, which makes things complicated. I can think of multiple ways how to approach this problem, but probably the simplest is to run a PSS & PAC analysis.

Add a PAC current source in parallel with your tank. Sweep the injection frequency and measure the voltage across the tank
a) amplitude (Q= one-sided relative 3dB bandwidth)
b) phase change (Q=d(phi)/d(omega) omega_0/2)

1 Yes, I am using the phrase measurement even though the desired information is obtained by simulation and not with an instrument.
Back to top
 
 
View Profile   IP Logged
Pages: 1
Send Topic Print
Copyright 2002-2021 Designer’s Guide Consulting, Inc. Designer’s Guide® is a registered trademark of Designer’s Guide Consulting, Inc. All rights reserved. Send comments or questions to editor@designers-guide.org. Consider submitting a paper or model.