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How do reduce N.F in the LNA design ?

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mitgrace

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Dear All:

I have design LNA , the gian i s enough , But the N.F is large. I don't have any sense to reduce the N.F . Does anyone have any comment ? Thanks
 

what process, what topology ?

usually nf is reduced by the input match and the amount of current that you are using, as well as the transistor sizing.

let me know process and topology and i can help more.
 

Every amplifier regardless its technology or topology contains noise sources. Some topologies are better than others. Once you have made the design, the amplifier has a minimum noise figure, most simulators are able to perform this measurement (ADS, MWO, Ansoft designer, ...). The minimum noise figure is obtained when the source impedance equals a certain value. Then you design you input matching network so that the actual source impedance is transformed into this optimum value. That's more or less the global story.
 

frist of all , u need to bias the transistor to the current which produce the minimum noise

then when design the input matching network , then match for minimum noise , get the Ropt , Zopt , and match to it


then u garantee that the transistor give minimum noise and u get the minimum noise for it

khouly
 

The electronic design is important but remember that the mechanical design in microwave or near frequencies is very important too.
One thing very important is that in semiconductors the working temperature is proportional to the noise generated.
I had hard to find problems in 10Gz band with noise and solved them only changing the mechanical design.Change the case , change the earth connections and put elements that heat as far away as I could.
 

Dear sir :

How do u simulate one MOS N.F in the spectre -RF tools ? I read some paper it can show the Overdrive and IP3 ,P1dB or N.F relation ? How can I do that simulation ? Thanks
 

Dear all :

My process is 0.13um RF for FM tuner, the band is 72 ~ 108MHz , widebanf design ? Any comment . Thanks
 

you can use the ADs to simulate it and you can test to reducing the current of the first stage of the LNA
 

Hi,

You may want to tune the noise matching, that often helps a lot.

Wish it helps,

Ruri
 

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