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Design >> RF Design >> about some concepts in RF design
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Message started by Esther on Oct 11^th, 2006, 6:34pm

Title: about some concepts in RF design
Post by Esther on Oct 11^th, 2006, 6:34pm

Dear all, I am very glad to find this forum. I am a newer for RF design though I had 5 years normal analog design experience before.

Currently I feel that I am NOT familiar with some concepts about RF design, phase noise etc. When I use SpectreRF to do pss and pnoise analysis, I don;t know how to fill in each item in the form. Actually I even don't totally understand what is pss, pnoise analysis....I suffer from this....

Can anybody give me some advice what kind of textbook or document can tell me clearly about all these basic concepts for RF?

Thanks in advance. :)

Title: Re: about some concepts in RF design
Post by Ken Kundert on Oct 11^th, 2006, 7:28pm

You might want to take a look at http://www.designers-guide.org/Analysis/rf-sim.pdf. And for information on phase noise, read the material on cyclostationary noise at http://www.designers-guide.org/Theory/.

-Ken

Title: Re: about some concepts in RF design
Post by loose-electron on Oct 11^th, 2006, 10:20pm

Might also want to pick up a book that covers the concepts from an academic perspective.

On my shelf for RF IC's:

RF Microelectronics - B. Razavi

Design of CMOS RF Integrated Circuits - Tom Lee

and there are mutliple others. Need a good grasp of the concepts associated with Linearity (IIP3 and IIP2) Inherent Noise (Input referred noise), Spectral spreading due to phase noise, the concepts associated with compouning of noise and linearity through a multistage system. Some other items as well, but if its fairly easy to pick up.

Title: Re: about some concepts in RF design
Post by Esther on Oct 22^nd, 2006, 8:28pm

Thanks Ken and Loose for the information. Just print out these docs, will read in details.

Ken, I have another question.

I am doing divider design. Following your papers on cyclostatioanary noise, I do pnoise analysis with noise type time-domain. In this form, I need to fill in Noise Skip Count or Number of Points. What does this mean? which one I should tick and commonly what is number I should put in?

Thank you very much..

Title: Re: about some concepts in RF design
Post by Esther on Oct 22^nd, 2006, 8:35pm

Last week I attended cadence RF methodology Kit workshop. I asked Bob how to simulate a divider because I can not find example for diviver in cadence domument but thare are always very detailed info for vco, lna and mixer. He told me it is better to simulate divider together with vco in this case input source is NONE. But I am a little confused that the phase noise is sum of vco and divider by this way. And I would like to know the phase noise of only divider..So what I should do?

Thanks a lot.

Title: Re: about some concepts in RF design
Post by Ken Kundert on Oct 22^nd, 2006, 11:19pm

There is no sense in including the VCO if you are only interested in the divider noise. To see how to simulate the noise of dividers, take a look at http://www.designers-guide.org/Analysis/PLLnoise+jitter.pdf.

The Artist interface is designed to allow you to plot the noise as it evolves over a cycle. In the extreme case, it would perform a noise analysis for every time point the simulator used during a cycle. This would take a long time, so it allows you to skip steps. The Noise Skip Count is used to specify how many time points it should skip between noise analyses. Since you only want the noise analysis to be performed at one time point, you should set this value arbitrarily high. Then the interface allows you to specify specific points you want the noise for. You would enter 1 for the Number of Points, then specify the particular point you wanted. You would use the time where the output crosses the threshold value for the circuit it would be expected to drive.

I believe the newer versions of SpectreRF allow you to simply specify the threshold voltage and direction, and it takes it from there.

-Ken