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Design >> RF Design >> Dependance of stability margins on the gain of Mixer?
https://designers-guide.org/forum/YaBB.pl?num=1364826041

Message started by iVenky on Apr 1^st, 2013, 7:20am

Title: Dependance of stability margins on the gain of Mixer?
Post by iVenky on Apr 1^st, 2013, 7:20am

I read that gain of the Mixer should not be high as it would degrade the stability margin. How can the gain degrade stability? Please clear me this doubt.

Thanks a lot.

Title: Re: Dependance of stability margins on the gain of Mixer?
Post by aaron_do on Apr 7^th, 2013, 8:24pm

Hi,

I haven't heard that about the mixer in particular, but definitely blocks with higher gain are more prone to instability. There may be an unanticipated feedback path through coupling for example...

regards,
Aaron

Title: Re: Dependance of stability margins on the gain of Mixer?
Post by raja.cedt on Apr 8^th, 2013, 3:24pm

hello,
Most likely systems with high gain will have a tendency to oscillate due to parasitic coupling for instance power amplifier power may coupled through substrate or bond wire inductance to LNA input this may create oscillations. In few cases lower gain may oscillate, so you have to check K-factor.

Thanks,
Raj.