[SI-LIST] Re: Pcie PLL bandwidth
- From: "Chen, Sherman" <sherman.chen@xxxxxxx>
- To: "balaseven@xxxxxxxxx" <balaseven@xxxxxxxxx>, "si-list@xxxxxxxxxxxxx" <si-list@xxxxxxxxxxxxx>
- Date: Mon, 16 Jun 2014 14:59:16 +0000
Bala,
Looks CPU is sending jittery signal. You may need to check with your ASIC
vendor what BW is used in the receiver PLL then you should apply the same BW in
scope PLL, or constant freq.
Best regards,
Sherman Chen
Signal Integrity
EMC Global Hardware Engineering
Tel: +86 21 60951100ext3329
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of bala
Sent: Wednesday, June 11, 2014 2:25 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Pcie PLL bandwidth
Hello,
I am validating chip-chip pcie gen 1 interface.My design has pcie link between
CPU<-->ASIC and CPU<-->FPGA.I set constant clock as my recovery clock in my TEK
scope and eye was good when ASIC and FPGA driving my CPU.Whereas, eye was bad
and too much jitter was observed at RX when CPU driving other two devices.I
changed my clock from constant mean to PLL (
1.5 Mhz bandwidth as specified in the pcie spec) and got same output(eye was
good) when ASIC and FPGA driving , interestingly eye was good at this time when
CPU driving other two devices.Everything seems okay when PLL was chosen as my
recovery clock.I know clock should be PLL for pcie compliance testing (min 1.5
Mhz BW) as mentioned in the pcie specification.My question is why eye was good
when other two devices driving my CPU in both the cases,whereas my eye was bad
when constant clock was chosen and it was good when PLL was selected.
Regards
bala
------------------------------------------------------------------
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:
