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Design >> RF Design >> calculated the noise factor of 2-most amp
https://designers-guide.org/forum/YaBB.pl?num=1211809123

Message started by wwm101 on May 26^th, 2008, 6:38am

Title: calculated the noise factor of 2-most amp
Post by wwm101 on May 26^th, 2008, 6:38am

in Federio Bruccoleri doctor degree’s paper
he assumes the MOST only have drain noise （channel noise）
then definitely　the drain noise I²_n/△f=4KT*r*g_m=4KT*NEF*g_m

in follow schematic， he calculated the noise factor equal to 1+NEF_a+4NEF(A_VF-1)/A_VF²　　at ΔNEF=NEF_b-NEF_a　And g_b+1/Z_L>>0（g_b+1/Z_L=g_b）　。

how to calculate it by hand?
Thank you in advance！

Title: Re: calculated the noise factor of 2-most amp
Post by pancho_hideboo on May 26^th, 2008, 5:18pm

wwm101 wrote on May 26^th, 2008, 6:38am:

in Federio Bruccoleri doctor degree’s paper
he assumes the MOST only have drain noise （channel noise）
then definitely　the drain noise I²_n/△f=4KT*r*g_m=4KT*NEF*g_m

In the above, "r" is equal to "NEF" ?. And this is typically 2/3 ?

wwm101 wrote on May 26^th, 2008, 6:38am:

in follow schematic， he calculated the noise factor equal to 1+NEF_a+4NEF(A_VF-1)/A_VF²　　at ΔNEF=NEF_b-NEF_a　And g_b+1/Z_L>>0（g_b+1/Z_L=g_b）

In the above, what do you mean by "NEF" in "4NEF" ? What is A_VF ?
What do you mean by "0（g_b+1/Z_L=g_b）" ?

Maybe a topology you refer is "Amp-1" in the following.

Quote:

http://doc.utwente.nl/55659/1/00933458.pdf

You can derive Noise Factor equation easily if you trace all formulations and equations in the above.

You have more detail documentation(PhD dissertation), don't you ?

Title: Re: calculated the noise factor of 2-most amp
Post by wwm101 on May 27^th, 2008, 6:04am

TO：pancho_hideboo
thank you very much for your attention。
i'm very sorry for my ague expression and clerical error

correct：
first ,in drain noise‘s expression ，the drain noise must defined as I²_n/△f=4KT*r*g_d0=4KT*NEF*gm，where g_d0 is the channel conductance for V_DS=0 and r is a bias-dependent parameter.For a long-channel MOS in saturation,r=2/3 and g_d0=g_m holds.For a deep sub-micron mosfet,r>2/3 and g_d0>g_m arise from the large electric field along the channel. NEF is short for "noise excess factor" ,NEF= r*(g_d0/g_m)>r ,introduced to quanify the excess of noise current with respect to a resistor R=1/g_m .
second, the noise factor of 3most amplify is equal to 1+NEF_a+4*ΔNEF*(A_VF-1)/A_VF² . where ΔNEF=NEF_b-NEF_a , gb+1/ZL>>0 (in the other way g_b+1/Z_L≈g_b) and A_VF is the voltage gain of amplifier.

Title: Re: calculated the noise factor of 2-most amp
Post by wwm101 on May 28^th, 2008, 6:44am

TO：pancho_hideboo

i have readed the paper you introduce。but i can't derivate the expression. how to derivate in detail?

thank you in advance!

Title: Re: calculated the noise factor of 2-most amp
Post by pancho_hideboo on May 31^st, 2008, 5:46am

wwm101 wrote on May 28^th, 2008, 6:44am:

i have readed the paper you introduce。but i can't derivate the expression. how to derivate in detail?

Do you truely trace equations ?
Show me your incomplete formulations to derive NF.

http://www.designers-guide.org/Forum/YaBB.pl?num=1209653115
You couldn't derive the above by yourself although it is very easy to derive.
This is a simple exercise level in school.

Title: Re: calculated the noise factor of 2-most amp
Post by wwm101 on May 31^st, 2008, 9:29pm

thank you very much ,i have derivated it ;D