From: firstname.lastname@example.org (boki)
Subject: Re: basic VCO question.( test, frequency adjust, matlab)
Date: 16 Dec 2002 07:52:25 -0800
NNTP-Posting-Date: 16 Dec 2002 15:52:26 GMT
"Mike" wrote in message news:...
> "boki" wrote in message
> > Hello thank you.
> > this is a very basic VCO circuit/question.
> > first question:
> > Is this circuit correct?
> > http://netcity6.web.hinet.net/UserData/bokiteam2001/vco%20cir.gif
> Not if you want it to oscillate. Your basic oscillator structure is a ring
> oscillator (M5,6,8,9), which has two inversions in the loop. If you add
> another stage (M5,8 is one stage), it will oscillate.
> However, it will only oscillate at one frequency.
> I think you're trying to build a current-starved ring oscillator. If you
> google for "current starved ring oscillator" (without the quotes), you'll
> find circuits that look like what you're trying to design. Take care to
> notice the differences.
> > could you please tell me how to test this circuit ?
> > If SPEC is:
> > Frequency: > 100MHz
> > Tuning range: > 10% or 20% or more
> > could someone give me some hint?
> Yes, but it sounds to me like you don't really know how the circuit works,
> or where the inputs and outputs are. Take a look at the lecture notes by
> Wilde in the google results. When you understand how it works, then you'll
> know how to test it.
> > the last question:
> > [Output spectrum analysis using Matlab].<---- How to do that ? I never
> > did that before... ><~
> > I mean, how to get datas from SPICE and input it to Matlab?
> In SPICE: .print v(oscillatornode)
> Edit the text output file with your favorite text editor, or write a python
> script to extract the data you want and put it in another file.
> In MATLAB: load yourfilename.txt -ascii
> -- Mike --
thank you! Mike ~ it is very helpful! :)