[SI-LIST] Re: =?gb18030?q?=B4=F0=B8=B4:?= HDMI Frequency Failing RE Test by 7dB!!!!
- From: hanymhfahmy@xxxxxxxxx
- To: ah.vinod@xxxxxxxxx,"SI-LIST" <si-list@xxxxxxxxxxxxx>
- Date: Thu, 24 May 2012 03:46:36 +0000
Hi Vinod. This issue is most probably rise/fall mismatch causing common mode
noise emission.
Try different drive strength n slew-rate. Then chockes on HDMI may be the
solution.
Sent via BlackBerry offered by Mobinil
-----Original Message-----
From: vinod ah <ah.vinod@xxxxxxxxx>
Sender: si-list-bounce@xxxxxxxxxxxxx
Date: Thu, 24 May 2012 08:33:54
To: SI-LIST<si-list@xxxxxxxxxxxxx>
Reply-To: ah.vinod@xxxxxxxxx
Subject: [SI-LIST] Re: 答复: HDMI Frequency Failing RE Test by 7dB!!!!
Hi All,
I will try out experimenting with current probes for root causing the
issue. Also I am going to EMI lab on Friday (India Time). Thanks for
great suggestions. Will keep you all updated on the test results:-)
Regards
Vinod A H
On Thu, May 24, 2012 at 7:34 AM, Zhenwei Wang (zhenwwan)
<zhenwwan@xxxxxxxxx> wrote:
> Hi Vinod,
> I went through the email about your issue. Yes, if the pixel clock is
> 74.25Mhz, the data rate is ten times of pixel clock, equal 742.5Mhz.
> Conceptually, TMDS signal have a virtual AC ground. So there is no DC current
> requirement through ground pin. My suggestion: you should check the parameter
> "inter pair skew" of each differential data line.
>
> BR
> Zhenwei(Jason) Wang
> Cisco Systems (Shanghai) Video Technology Co., Ltd.
>
>
> -----邮件原件-----
> 发件人: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] 代表
> vinod ah
> 发送时间: 2012年5月23日 21:58
> 收件人: SI-LIST
> 主题: [SI-LIST] HDMI Frequency Failing RE Test by 7dB!!!!
>
> Hi All,
>
> I am designing a board with HDMI input and HDMI output. I am facing
> EMI issue at 742.5MHz (failing FCC limits by 7dB) when running 1080p30
> on both Input and output HDMI i.e. BLu ray player connected to HDMI
> input connector of my board is giving out data at 1080p30 and HDMI out
> of my board is connected to TV which is also 1080p30 content. So i am
> unable to find out how is 742.5MHz coming out as radiation as it is
> 10th Harmonic of pixel clock 74.25MHz!!!!!!!. I am not facing any
> issues with other harmonics except for this. So i am totally confused
> on how to go about debugging this issue.
>
> Note: All the signals are routed on top layer without vias and all
> signals have solid ground plane reference. The blu ray player and TV
> used, is tested for radiation and no significant levels seen.
>
> Regards
> Vinod A H
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