Here is the problem.
It seems to me that using either system effectively reduces efficiency of
the amplifier.
The Cartesian loop system modifies the input signal to linearize
the amplifier this changes the amplifiers efficiency. So the benefit of
high efficiency goes out the window when using this system with SSB.
The polar loop system is a variation of the DAF amplifier. We have
had lots of discussions about that here. With a method of compensating for
phase shift due to impedance changes due to variations in the modulated
supply voltage. Also, I think the efficiency will also suffer at low or
intermediate signal levels.
Check out:
http://www.ece.ucdavis.edu/~spbruss/research/linearizer_methods_overview.pdf
At 03:02 PM 3/8/2005 -0500, ToddRoberts2001@aol.com wrote:
>In a message dated 3/8/2005 12:48:58 PM Eastern Standard Time, G3rzp@aol.com
>writes:
>How do you make them linear? Can you maintain the efficiency if you use
>polar or cartesian loop linearising?
>
>73
>
>Peter G3RZP
>
>I don't think it is possible to make a Class E amplifier linear in the way
>that a Class AB amplifier is linear. One practical way to use a Class E
>amplifier to amplify SSB is to configure it as an EER - Envelope
>Elimination and
>Restoration amplifier. Dr. Fred Raab has done much good research and written
>several papers on the EER technique. 73 Todd WD4NGG
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