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