[SI-LIST] Re: Answer for how to couple noise to the PDN of oscillator
- From: Istvan Novak <istvan.novak@xxxxxxxxxxx>
- To: Zhangkun <zhang_kun@xxxxxxxxxx>
- Date: Fri, 16 May 2008 08:05:55 -0400
Zhangkun,
Good summary, I would offer just one more comment regarding your #5 below:
If your PDN requirement is 0.1 ohms with a BW of 25MHz, you can create
a flat resistive impedance, so that you dont necessarily need to worry
about
antiresonance between the PDN capacitance and feed inductance.
You can take POSCAP
or tantalum capacitors at low frequencies so that their cumulative ESR
is 0.1
ohms, and complement it with appropriate ceramic caps to give 0.1 ohms at
high frequencies as well. You can take small-size 1-ohm resistors and MLCCs
in series in sufficient numbers to give you 0.1 ohms and the <1nH inductance
you need for 25MHz BW. Or, you could use a dozen of the TDK controlled
ESR MLCCs: CERB3UX5R0G105MT
on http://www.component.tdk.com/cap_technotes.php#
Regards,
Istvan
Zhangkun wrote:
> Dear all:
>
> Based on the talk about how to couple noise to the PDN of oscillator. I have
> gotten several solutions:
>
> 1. Do not consider the dis-match
> 1) Connect the signal to the PDN directly
> 2) Measure the coupled noise on the PDN
> 3) Calculate the ratio between the noise and the jitter
>
> 2. By means of 1:N transformer to lessen the dis-match.
>
> 3. By means of other IC, creat a noise source with low impedance.
>
> 4. By means of opamp, which is of low impedance.
>
> 5. Because the low impedance of oscillator PDN is capacitive, there
> would be a parallel resonance with a inductor(serial with a resistor).
>
> Hope this would be helpful.
>
>
> Original question:
>
> Now we are studying the effect of power noise on jitter. We meet a problem,
> how to couple noise to the PDN. For example, we want to couple noise of
> 25MHz into the PDN of oscillator. However there is impedance dismatch. The
> impedance of signal source is about 50ohm and that of PDN is about 0.1ohm.
> The energy would be reflected.
>
> Best Regards
>
> Zhangkun
> 2008.5.16
>
>
> ------------------------------------------------------------------
> To unsubscribe from si-list:
> si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
>
> or to administer your membership from a web page, go to:
> //www.freelists.org/webpage/si-list
>
> For help:
> si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
>
>
> List technical documents are available at:
> http://www.si-list.net
>
> List archives are viewable at:
> //www.freelists.org/archives/si-list
> or at our remote archives:
> http://groups.yahoo.com/group/si-list/messages
> Old (prior to June 6, 2001) list archives are viewable at:
> http://www.qsl.net/wb6tpu
>
>
>
>
>
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.net
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
