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    Layout PCB RF AMplifier

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    hello i want to ask,if i design the layout pcb like a picture, if the transistor input that I rounded was sharpened like in the picture what would affect the matching impedance?

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    Re: Layout PCB RF AMplifier

    Are you sure that the Impedance Matching Circuits have been well designed ?? Because TLs seem to me a bit weird..( Their Widths are too large )



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    Re: Layout PCB RF AMplifier

    yes sure, this my schematic on ADSClick image for larger version. 

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    Re: Layout PCB RF AMplifier

    Sorry ididnt understand about ground connection, and do you think that can be realized? because the simulation results are very good?



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    Re: Layout PCB RF AMplifier

    Not sure how you arrived at the TL matching network. It looks considerably different from reference design in CGH40006S datasheet. Consider that the MLIN model doesn't cover the discontinuities at the line ends.

    The worst point of your layout is however the ground connection of bypass capacitors and transistors. I'm sure that the demonstration PCB uses multiple small vias below the QFN exposed pads. The different ground connection of capacitors is obvious on the photo.

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    the simulation results are very good
    Which simulation results? Did you simulate the actual geometry, e.g. with ADS Momentum? If not, can you know how your PCB behaves? The demonstration board is assuming 35 pH source inductance for the transistor, can be hardly achieved with a single via.



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    Re: Layout PCB RF AMplifier

    So, what should I do ? Are there suggestions or can you help?



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    Re: Layout PCB RF AMplifier

    Quote Originally Posted by Fhadz View Post
    Sorry ididnt understand about ground connection, and do you think that can be realized? because the simulation results are very good?
    What is your target ?? Designing a Power Amplifier or ?? At which frequency ??

    Can you illustrate your simulation results here ??



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    Re: Layout PCB RF AMplifier

    This for my final project at my collage, i choosw 5,6 Ghz imean a simulation good is a S parameter simulation its reach my target



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    Re: Layout PCB RF AMplifier

    I believe that the simulation results are good. But the simulation circuit is far from representing your PCB design. It has huge parasitic inductances due to insufficient ground connections. And the matching transmission line structures need more accurate modelling than by simple MLIN segments.



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