Negative Resistance Transformation using Quarter Wave

[hussard11]

Hi everybody
I need to transform a negative resistance of -5980 Ohms into a smaller value as it has to be generate by a transistor (Mesfet) by using a characteristic impedance of 90 Ohms for example. I'm using a quarter wave transformer with the equation:
Zin=Zo^2/Rl. I'm getting only an imaginary part but my supervisor told me I should only obtain a real part.
Please someone help me.
THks by advance
Regards

 

[firewind]

if it has negative real part then something is wrong and can cause oscillation due to reflection waves. Where are you div your RI? Is it at the load? It should be at the load.

 

[hussard11]

In fact , the real part has to be negative because im designing a negative resistance circuit the compensate the losses in a resonator.

 

[wavemanlee]

you can take a looks at Razavi's books
he briftly metioned this topic.
basically his topology is like a cross-coupled Gm cell.
that helps with loss issue.

 

[firewind]

hi there, so have you figured out how to do it? I just learned how to do matching. This is very interesting thing and I would like to know the solution too. If you found out the solution, please shred some light me.