si14
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Hi all,
I am designing a LNA. In ADS I get the stability factor 1.004 and the Stability measurement 0.391 but the stability circles (both source and load) include the whole Smith Chart!
The Stability factor and measurement say that LNA is stable, but the stability circles conflict with this.
Under these conditions, can I trust that the amplifier is stable and go for the fabrication?
If no, how can I stabilize this? Should I add a resistor to the circuit? This leads to higher noise figures which is undesirable.
I should mention that the transistor was unstable at first, then I put a TL in source. After that I got these results.
And the final point: if I add a shunt resistor in drain, the whole Smith chart would be in the stable region and the stability factor would be about 3 and the stability measurement about 0.7 then. But as I said, this definitely leads to worse noise figures..
If anyone has any idea, I would be glad to hear that.
Thank you very much,
Cheers
I am designing a LNA. In ADS I get the stability factor 1.004 and the Stability measurement 0.391 but the stability circles (both source and load) include the whole Smith Chart!
The Stability factor and measurement say that LNA is stable, but the stability circles conflict with this.
Under these conditions, can I trust that the amplifier is stable and go for the fabrication?
If no, how can I stabilize this? Should I add a resistor to the circuit? This leads to higher noise figures which is undesirable.
I should mention that the transistor was unstable at first, then I put a TL in source. After that I got these results.
And the final point: if I add a shunt resistor in drain, the whole Smith chart would be in the stable region and the stability factor would be about 3 and the stability measurement about 0.7 then. But as I said, this definitely leads to worse noise figures..
If anyone has any idea, I would be glad to hear that.
Thank you very much,
Cheers