DOC

sensitivity test EMC issue FA report V110

By Tom Dunn,2014-04-26 23:14
16 views 0
sensitivity test EMC issue FA report V110EMC,test,Issue,TEST,issue

    Version Confidential

    AUTELAN V1.10 internal

    Total 6 pages Engineering V5 t7 f7 sensitivity test EMC issue FA

    Report

V5 t7 f7 2.4G frequency sensitivity test EMC issue FA report

    Prepared 邱志强 Spesoor Date2012/ 07/ 19

    Approved __ _ Date / /

    Permitted __ _ Date / /

    Beijing AUTELAN Tech Ltd com.

     ALL right reserved Donnot spread

    Modified Records

    Prepared Version Reason Interpretation Date by V1.00 New publish Draft Spesoor 2012-7-19

     V1.10 Modify some errors Improve the template Spesoor 2012-7-25

     FA CONTENTS

    CONTENTS ............................................................................................................................. 1 1. ISSUE DESCRIPTION ..................................................................................................... 2 2. FAILURE RATE .............................................................................................................. 3 3. INITIAL ANALYZE ........................................................................ 错误?未定义书签。4 4. CHECK IT OUT EMI ISSUE ............................................................. 错误?未定义书签。5 5. CONCLUSION .............................................................................. 错误?未定义书签。6 6. RESOLVING SOLITIONS ................................................................................................. 7

1. Issue descriptions

    We encountered t7 f7 frequency sensitivity test problems on V5 2.4G onboard Radio.

    The good results of sensitivity test on data rate 54 t7 f7 should be very stable, the good design ‘s

    sensitivity test delta should be equal and beautiful as below red frame Mark, especially for f7 data rate, it should be all -5 .

    But the bad sensitivity test results as below , the f7 2462MHz items failed ,out of our criteria, Moreover ,the sensitivity becomes worse by the frequency increasing, so 2462MHz band appeared failures easily.

    In addition , actually, it seems has a regular that the failures have a common symptom on CH1 .

    The following log captured from another failure , it is more serious.

2. Failure rate comfirmation

    We had 5 sample failed units test at different test environments which both in an shielding box or shielding room where from all of our OEM manufacturers , in AllWINS ZOWEEHuaxiang etc. and

    also in AUTELAN.

    The failure rate was 100%, so it was in production line,.

    So the factors that impact the terrible sensitivities are not from external Radio signal interference but exist in DUT internal .

3. Initial analyzer

     After tested in different kinds of test station and environments , the failure could be duplicated and occurred at any time and every test from different places.

     We tried to experiment the actions which re-heating re-solderingand replace some RX main

    components such as respective path LNA diplexersbalun BPF filters and antenna switchs , but

    it not effects.

     However, once I dropped off the Metal heating Sink on AR9344 Chip , I found that ,significantly the sensitivity appeared beautiful test results on our sight, continuously testing many times it shows stable and the sensitivity results was described as above expecting good results, and then I equipped the chip’s Metal Sink ,the test returned terrible again.

     Implementing these steps repeatedly, we could confirm that the problem was on this metal Sink.

     .

4. Check it out EMI issue

    The next analyzed steps .

    what ‘s more ,we performed all 5 sample units ,the outcome is it would perform

    absolutely different sensitivity test results on drop off or mounting the Metal heat Sink.

    Therefore, I could get a conclusion that the factor that caused of sensitivity bad was this

    Metal Sink, it should be EMI issue.

    The test logs as attached, it indicated that the EMI was more serious on CH1 than

    the CH2 ,and more terrible on high frequency fro 2412 MHz band to 2462 MHz

    increasing delta value could simply indicate it becoming bad, it may be an Metal sink

    EMI issue or CH1 RX path radio layout EMI issue.

    Thus, on the opposition , we fetch another kind of heating Sink which was made of ceramic ,

    testing at different test stations and environments ,these sample units still performed

    beautiful and stable sensitivity test result after installing Ceramic Heating Sink.

    So we can conclude that the final issue was an EMC design issue on the other hand , we

    could not utilize Metal Heating Sink on Radio chips considering EMI issue.

5. Conlusion

    Final issue was an EMC design defect , we could not utilize Metal Heating Sink on Radio

    chips considering EMI issue.

6. Resolving Solutions

     For Short-term solution

    The PBCA ART calibration could performed with picking off heat Sink

For long-term solution :

We need modify the BOM using ceramic heating sink and improve the EMC

design .

Report this document

For any questions or suggestions please email
cust-service@docsford.com