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EVM Degradation at 54 Mbps OFDM (802.1g) - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


 Post subject: EVM Degradation at 54 Mbps OFDM (802.1g)
Posted: Wed Jan 20, 2010 9:03 am 
 
Colonel
User avatar

Joined: Wed Aug 16, 2006 8:20 am
Posts: 31
Location: India
Hi
I designed a 802.11b/g Transceiver using Airoha's AL7230 Chip-set. When I do EVM measurements on the Transmitter antenna port using a Vector Signal Analyzer, the EVM passes for all modulation Schemes and at all output power level (17 dBm maximum) except 54 Mbps OFDM. When I reduce the output power level by approximately 5dB then the EVM test passes.

Is this problem due to the Crest Factor of 54 Mbps OFDM signals. The Chip-set data sheet satisfies the EVM requirements for a Power output of 17 dBm. I have only placed a Balun and a switch at the Chip-set Transmitter output pins. Can this degrade my PA linearity

_________________
Ashish Bondia,
Design Engineer- RF




Posted  11/12/2012
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