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Driver design of the power amplifier

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OZZAA

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I want to design a PA with 2 stages (Driver (Cascode topology) and the main PA (Common source)) to give for example maximum power equals 30 dBm (@10 GHz) with overall gain 15 dB.
I calculated the aspect ratio of the transistors of the main PA to be in class AB.
its S21 is about 6 dB.
How I can choose the aspect ratio of the driver stages to feed the main PA properly.

I know I have to make the gain of the driver stage (s21) equals 9 to give the overall gain equals 15 dB.
and what is next?
you can assume any output and input resistances and any other wanted data, I just want the concept.

Thanks in advance
 

OZZAA said:
I want to design a PA with 2 stages (Driver (Cascode topology) and the main PA (Common source)) to give for example maximum power equals 30 dBm (@10 GHz) with overall gain 15 dB.
I calculated the aspect ratio of the transistors of the main PA to be in class AB.
its S21 is about 6 dB.
How I can choose the aspect ratio of the driver stages to feed the main PA properly.

I know I have to make the gain of the driver stage (s21) equals 9 to give the overall gain equals 15 dB.
and what is next?
you can assume any output and input resistances and any other wanted data, I just want the concept.

Thanks in advance
Click to expand...

you need to design driver with the output power that is needed at the input of your second stage --> Pout 1dB (driver) = Pin (PA)

Then you will find optimum ZL and you have optimum Zs for your main PA you have found from source pull
design a matching circuit that matches ZL(driver) to Zs* (PA)

pick class B for driver for having better efficiency even class C since you dont need high output power.
 
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    OZZAA

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you need to design driver with the output power that is needed at the input of your second stage --> Pout 1dB (driver) = Pin (PA)
Click to expand...
you mean that, if the OP1dB (output power of 1 dB compression point) of the main PA occurs at Pin (IP1dB compression point) = 6 dBm.
I have to design the driver where its OP1dB at 6 dBm (the IP1dB of the main PA) ????
 

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