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Message started by jlee on Jul 15^th, 2007, 1:22am

Title: ON The Designer's Guide to High-Purity Oscillator
Post by jlee on Jul 15^th, 2007, 1:22am

Hey Guys,

Have you read the book "The Designer's Guide to High-Purity Oscillator"? What about this book? Is it really helpful to optimize phase noise of VCO?

Could you please give me your comments on this book?

Thanks!

Title: Re: ON The Designer's Guide to High-Purity Oscilla
Post by chenyan on Jul 15^th, 2007, 4:38am

I have to say, there are quite a number of mistakes in this book.

Title: Re: ON The Designer's Guide to High-Purity Oscilla
Post by neoflash on Jul 15^th, 2007, 5:35am

Author is going to upload a errata list. However, I'm not sure about the time.

Basically, it follows Abidi style. Make those complicated problems in simple and intuitive way. This gives u a lot of qualitve preview of LC-tank.

Title: Re: ON The Designer's Guide to High-Purity Oscilla
Post by jlee on Jul 15^th, 2007, 6:52am

Thank you, Chenyan and neoflash.

Actually, I have read the papers on optimizing phase noise by Emad Hegazi, Jacob Rael & Asad Abidi.

I just wonder whether there are other tricks mentioned in this book. If so, I plan to spend some time going through this book.

I am really puzzled in the design of LC-tank based VCO.

Title: Re: ON The Designer's Guide to High-Purity Oscilla
Post by chenyan on Jul 15^th, 2007, 8:12am

Even I said there are some mistakes in the book, I still recommend you to read the book. There is not many tricks in the book except the noise filtering you alread read, however, it still provides you some insight on phase noise and LC VCOs. But be caeful of the deductions. Also, I would recommend you to do some pxf simulations when you read along. Just to get impresions how each noise source contributes to your phase noise.

Title: Re: ON The Designer's Guide to High-Purity Oscilla
Post by jlee on Jul 15^th, 2007, 7:05pm

Thank you, chenyan.

I have already used filtering such as choke inductor for 2nd harmonic rejection. But, when I select the choke inductance, I just run Pnoise to estimate whether I have used the right incutance for optimized phase noise.

Is there any other way to confirm the choke inductance such as PXF, PAC?

If so, could you please give me more detailed anaysis method?

Thanks!

Title: Re: ON The Designer's Guide to High-Purity Oscilla
Post by chenyan on Jul 16^th, 2007, 7:20am

Hi Jlee, be aware of the parasitic caps on the node you connect your inductor. This will shift the resonate frequency of your noise filtering.

Title: Re: ON The Designer's Guide to High-Purity Oscilla
Post by jjrael on Jul 16^th, 2007, 10:01am

Hello,

This is Jacob Rael. I am planning on releasing an errata here in a about a month. I am having some friends review the text to see if I caught all the errors.

Also, I used PXF to find that the noise from the current source was carried on the 2nd harmonic. The easiest thing to do is add a 0 amp current source in parallel with your current source transistor and use PXF to simulate the gain from the current source to the output voltage. As long as you divert the 2nd harmonic to ground, the performance should not be too sensitive to the inductor or cap values. However, flicker noise is another beast...

jr

Title: Re: ON The Designer's Guide to High-Purity Oscilla
Post by jlee on Jul 16^th, 2007, 9:08pm

Thank you, chenyan and Rael.

Also, I have noticed that the parasitic cap on the source of negative gm transistors has impact on the filtering effect.

Actually, 2nd harmonic filter can be used to improve phase noise in 1/f^3 regiion. But I found it is really sensitive to the choke inductance and cap on that node.

Rael, could you please give some comments on how to design the 2nd harmonic filter based on 1/f^3 phase noise improvement, especially how to choose the choke inductance?

Thanks