# How should be Pin1dB less or more compared with Pout1dB?

1. ## How should be Pin1dB less or more compared with Pout1dB?

Hi, Suppose If I want 20 dBm output power @ 1 dB compression point, don't we need to consider how much power we need to give at the input? In the sense that Is It appropriate to give input power of 20 dBm to get 20 dBm output power, then in this case there is no power amplification. Ideally, How should be the Pin1dB in a power amplifier. Thanks.

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2. ## Re: How should be Pin1dB less or more compared with Pout1dB?

Sorry, what? I am not sure I understand the questions. Ideally input/output compression is infinite I guess. And Pout.dB=Pin.dB+Gain.dB . So same is true for input/output compression points.

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3. ## Re: How should be Pin1dB less or more compared with Pout1dB?

P1dB(out)=Power Gain+P1dB(in)

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4. ## Re: How should be Pin1dB less or more compared with Pout1dB?

Originally Posted by BigBoss
P1dB(out)=Power Gain+P1dB(in)
Thanks Correct. So our goal should be to increase Power Gain as much as possible, on the hand can I also say that Pin1dB should be as less as possible?

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Originally Posted by frankrose
Ideally input/output compression is infinite I guess. And Pout.dB=Pin.dB+Gain.dB . So same is true for input/output compression points.
Oh I didn't think in this direction, so ideally there shouldn't be any compression that means Pout and Pin should have linear relation until infinite. In this sense, Pin1dB (Input 1 dB compression Point) should be as high as possible. correct?

5. ## Re: How should be Pin1dB less or more compared with Pout1dB?

In order to hold the amplifier in linear region with lesser harmonics, input power has to be a bit ( 2-4dB) less than P1dB (in).
Increasing of Power Gain has no sense at all, absolute non-linearity is defined by active device itself even the Power Gain is high or low..

6. ## Re: How should be Pin1dB less or more compared with Pout1dB?

Originally Posted by circuitking
Hi, Suppose If I want 20 dBm output power @ 1 dB compression point, don't we need to consider how much power we need to give at the input? In the sense that Is It appropriate to give input power of 20 dBm to get 20 dBm output power, then in this case there is no power amplification. Ideally, How should be the Pin1dB in a power amplifier. Thanks.
I should say I need at least 20 dBm output power at P1dB(out) that means I can have 20 dBm even before reaching P1dB(out).

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7. ## Re: How should be Pin1dB less or more compared with Pout1dB?

Originally Posted by circuitking
Hi, Suppose If I want 20 dBm output power @ 1 dB compression point, don't we need to consider how much power we need to give at the input? In the sense that Is It appropriate to give input power of 20 dBm to get 20 dBm output power, then in this case there is no power amplification. Ideally, How should be the Pin1dB in a power amplifier. Thanks.
Of course you need to consider that. Your measurement equipment can only deliver a maximum amount of power without itself compressing. If you do not have enough gain, then you cascade the stages to increase the gain.

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