[SI-LIST] Re: When measuring S-parameter in VNA, what does power level (0dbm or -15dbm) affects the results?
- From: "Orin Laney" <olaney@xxxxxxxxx>
- To: <issue.lu@xxxxxxxxxxx>, "'si-list'" <si-list@xxxxxxxxxxxxx>
- Date: Tue, 8 Jul 2014 20:30:58 -0700
The results should not vary for linear circuit elements since determining S
parameters is a ratiometric process. Raising the level can directly improve
s/n at frequencies where ratios are low. Differences versus level
indicate the presence of nonlinearities. Most RF semiconductors devices are
only "quasilinear", so there is no measurement benefit gained by driving
them hard (see X-parameter app notes to understand this instance). The
chosen VNA level is therefore a balancing act between adequate s/n ratio and
not overdriving the device under test. Often the band of usable levels is
wide enough to wonder why different levels are even offered, but then there
are the times when it's more like walking a tightrope. In general, test at
the lowest level that provides adequate s/n. Then raise the level for
comparison if you want to check linearity. It's a good thing when the
results barely change.
Orin
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of steve ham
Sent: Tuesday, July 08, 2014 8:11 PM
To: si-list
Subject: [SI-LIST] When measuring S-parameter in VNA, what does power level
(0dbm or -15dbm) affects the results?
When measuring S-parameter in VNA, what does power level (0dbm or= -15dbm)
affects the results?As I measured with the variation of = power level in
Agilent VNA, the results barely changed.
------------------------------------------------------------------
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 forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
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 forum is accessible at:
http://tech.groups.yahoo.com/group/si-list
List archives are viewable at:
//www.freelists.org/archives/si-list
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
