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  1. #1
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    Out of band stability of RF power amplifier

    Hi,
    I have designed doherty power amplifier for 3.4-3.6 GHz band. After many optimization process, I get the required specifications. However, the simulation results show instability at 500 MHz to 1 GHz (K<0), and at 1.4 GHz (K<1). For other frequencies from 0 to 6GHz the amplifier is stable. So, Is the instability at the above mentioned frequencies which are out of band frequencies will affect the performance of my design especially in the fabrication process ? as for simulation I have not see any effect. Thanks in advanced

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  2. #2
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    Re: Out of band stability of RF power amplifier

    Hi,
    I guess it will affect. Simulate transient oscillation is not obvious. It is not always easy to start the oscillation in simulation, but in real life the circuit can generate out of band oscillation which produce harmonics, consume power, cause reflections.
    "Try SCE to AUX." /John Aaron/



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  3. #3
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    Re: Out of band stability of RF power amplifier

    Have you ever drawn Load and Source Stability Circles for the bands which are root cause of instability ?? There may be a small portion/extreme region that makes the amplifier unstable..
    That's sometimes acceptable..



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