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Post subject: EVM Degradation at 54 Mbps OFDM (802.1g)
Posted: Wed Jan 20, 2010 9:03 am
Joined: Wed Aug 16, 2006 8:20 am
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
Design Engineer- RF