[SI-LIST] 答复: HDMI Frequency Failing RE Test by 7dB!!!!
- From: "Zhenwei Wang (zhenwwan)" <zhenwwan@xxxxxxxxx>
- To: <ah.vinod@xxxxxxxxx>, "SI-LIST" <si-list@xxxxxxxxxxxxx>
- Date: Thu, 24 May 2012 10:04:41 +0800
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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