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  1. #1
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    RF Power amplifier stability

    I have designed class AB Power amplifier for 3.4-3.6 GHz band. When i checked the stability, the amplifier was stable over the entire band (K>1). But for out of band at certain frequencies (0.5 to 1.2 GHz & 3.9 GHz ) is unstable. So, Is this condition will have an effect on the PA's performance?

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  2. #2
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    Re: RF Power amplifier stability

    The amplifier may oscillate-not definitely but-.If K<1, the amplifier is conditionally stable so certain load and source impedances may drift it into oscillation.If K<0, the amplifier will probably oscillate..
    Adding resistors at input and/or at output may help you or highpass/lowpass filters can also help to reduce the risk.


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  3. #3
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    Re: RF Power amplifier stability

    Quote Originally Posted by BigBoss View Post
    The amplifier may oscillate-not definitely but-.If K<1, the amplifier is conditionally stable so certain load and source impedances may drift it into oscillation.If K<0, the amplifier will probably oscillate..
    Adding resistors at input and/or at output may help you or highpass/lowpass filters can also help to reduce the risk.
    I have added resistor in series and helped in enhancing the stability. but on the other side degraded the gain too much.



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  4. #4
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    Re: RF Power amplifier stability

    Quote Originally Posted by Mabrok View Post
    I have added resistor in series and helped in enhancing the stability. but on the other side degraded the gain too much.
    Parallel resistors are used at input/output or both..Consider also highpass/lowpass filter combination.
    There are numerous solution for the stability..


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