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Sparam resonance tuning problem

robert 21

Hello, I am trying to use two inductors in my LNA as shown bellow to have a S-PARAM response so i will have S11 with lowerst possible values and tweak them for matching network. However when i ran EXPLORER live tuning with SParam as shown bellow i get no change in the response.

I know that Cgs and Cgd with the inductors having a resonance so by Varying L value i should have seen the change in resonance location,

But there is no change.Where did i go wrong?

Thanks. 

Parents

  • Given that the response is in micro dB, it means your S11 is very close to 1 at the frequencies you're plotting - which means it's effectively open circuit. I used a similar circuit (it's a bit odd, but I did it anyway) albeit with gpdk45, but for me there is a resonant point at about 44GHz and 174GHz (of course, this will depend on your transistors) (with 1nH inductors). So I suspect the issue is that your stop frequency in the s-parameter  is too low. I see the resonant frequency move as I alter Ls, for example:

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  • Given that the response is in micro dB, it means your S11 is very close to 1 at the frequencies you're plotting - which means it's effectively open circuit. I used a similar circuit (it's a bit odd, but I did it anyway) albeit with gpdk45, but for me there is a resonant point at about 44GHz and 174GHz (of course, this will depend on your transistors) (with 1nH inductors). So I suspect the issue is that your stop frequency in the s-parameter  is too low. I see the resonant frequency move as I alter Ls, for example:

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