Re: Réf. : Re: Re: 5.7 GHz PAs
I believe that all WiFi systems employ OFDM modulation schemes.
This is a multi carrier modulation with an inherent requirement for linearity in any amplifiers.
Because of the multi-carrier nature of the signal, any amplifier must be able to handle, to some extent, the elevated peak voltages associated with this. The crest factor of an OFDM signal is regarded as 10dB. For practical amplifiers you don’t need to necessarily rate them at 10 times the wanted power out. Depending on the tolerance to intermodulation product errors, you may get away with rating the amplifier with 6dB headroom (more or less) I suspect these amps have less headroom, but because the peak voltages are statistically distributed, the error rate probably doesn't increase too much, and given the robust nature of Wifi, you get away with it ( or the user doesn't notice that the error rate has gone up)
This is probably how is reported that you can get 4W out of these amplifiers, which i presume was measured somewhere about the 1dB Compression point, ie satisfactory for SSB
At the rated 2.5W, it will almost certainly be really quite linear and below the 1dB compression point.
They do indeed look like good value.
I am tempted to get one to play with myself.
Sent: Sunday, August 07, 2016 10:28 AM
Subject: Réf. : Re: [ukmicrowaves] Re: 5.7 GHz PAs
No virus found in this