Curios_Eng
Newbie level 3
Hello ,
I am designing an LNA for 481 MHz. Using the transistor BFP420. As a method I am using the complex conjugate matching at output. I have 75 ohms as input and output resistance.
1 - I choose GammaS from the stabil region
2- calculate Gammaout from gammas
3- Find gammaout Conj
4- Check if gammaout and gammaoutconj are in stabil region
5. Make conjugate matchin at output (GammaL =Conjggammaout)
6- design the matching circuits
7- Check if the matching circuit are resulting correctly .
I did all these steps, When I look at S22 after adding the matching circuits to circuit it shows 75 ohms. (Means that the complex conjugate matching is correct).
However the problem I have is after the matching circuit the stability factor K, is still smaller than 1. My colleagues checked the design I all approved that there is not any mistake.
Is there anyone knows what can cause this? It this so weird and I could not find the problem.
Thank You for your help in advance .
I am designing an LNA for 481 MHz. Using the transistor BFP420. As a method I am using the complex conjugate matching at output. I have 75 ohms as input and output resistance.
1 - I choose GammaS from the stabil region
2- calculate Gammaout from gammas
3- Find gammaout Conj
4- Check if gammaout and gammaoutconj are in stabil region
5. Make conjugate matchin at output (GammaL =Conjggammaout)
6- design the matching circuits
7- Check if the matching circuit are resulting correctly .
I did all these steps, When I look at S22 after adding the matching circuits to circuit it shows 75 ohms. (Means that the complex conjugate matching is correct).
However the problem I have is after the matching circuit the stability factor K, is still smaller than 1. My colleagues checked the design I all approved that there is not any mistake.
Is there anyone knows what can cause this? It this so weird and I could not find the problem.
Thank You for your help in advance .
