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Well... Actually, i don't know how ADS calculates Zin. But i take it as the exact Zin of the circuit, and compare it with my formula(i also take it as the exact Zin).
In this case, i really don't know what is wrong. :(
The Zin formula is from electronics letters. I guess it is right.
Thanks!
I used Zin in ADS , and I have tried to calculate the resistance only circuit, the result is ok.
I am now wondering if I have correct Cgs.
I got Cgso, Cox from mosis. Is it believable?
Thanks!
but after i changed these, the result remains the same.
Z =
0.0001 - 0.1391i
clear;clc;clf;
L=0.18*10^-6;
Width=20*10^-6;
cgso=8.58E-10;
cgdo=8.58E-10;
cox=8.4222*10^-3;
gds1=0.00017156;
gds2=0.000172916;
gm1=0.006982440;
gm2=0.006982440;
cgs1=cgso+(2/3)*cox*L*Width...
Thanks!
but after i corrected these two mistakes, the result remains the same.:-(
clear;clc;clf;
L=0.18*10^-6;
W=20*10^-6;
cgso=8.58E-10;
cgdo=8.58E-10;
cox=8.4222*10^-3;
gds1=0.00017156;
gds2=0.000172916;
gm1=0.006982440;
gm2=0.006982440;
cgs1=cgso+2/3*cox*L*W;
cgs2=cgso+2/3*cox*L*W...
this is my circuit in ADS
this the theory's formula of Zin
this is the matlab program i used to calculate
the result is Z =
0.0001 - 0.1391i
but in the ADS
as you could see, the result is totally different. i am really confused. this is my homework please help! Thanks in advance!
Well, I didn't have it.
You are right, if current flow to the outer circuit from inner sources, the outer circuit became part of the active circuit.
Then if I changed the impedance of term , mosfet's bias would change.
I really appreciate your help!
You're right! My circuit has dc current sources and voltage source to bias mosfet
I don't quite understand DC coupled.
Would you please explain it? Thanks!
Best regards!
I have tried to use Zin function of S-para to measure passive circuit (ex. just R of 100 Ohm) and result is right(no matter how i changed the impedance of Term's).
but when i use it to measure active circuit, the result seems to be the function of impedance of Term's. Why?
Thanks!
Best wishes!
Thanks for your help bro!
This is where i find CGS=CGSO . After i read your post, i found that this pic just wants to illustrate overlap cap. and i misread it to Cgs = Cgso.
and i think this pic is wrong , it should be CGS=CGSO*Weff.
Mask W and Actual W, which one is the width of nmos we...
I have tried to use Zin of S-para to measure passive circuit (ex. just R) and result is right.
but when i use it to measure active circuit the result related to the impedance of Term. Why?
Thank you!
i would appreciate if you could figure out where i am wrong!
this is the model i use: https://www.mosis.com/cgi-bin/cgiwrap/umosis/swp/params/tsmc-018/t92y_mm_non_epi_thk_mtl-params.txt
in the model:
Vth 0.50 volts
K' (Uo*Cox/2)...
yes, but why is 200kOhm in parallel? shouldn't it be 1.103 in series ?
thx! your calculation is right !
but i still don't understand , i calculate in this way :
Y=jwc+1/(jwL+R) , where R is 1.103 Ohm , so C=L/(w^2*L^2+R^2).
what is wrong?
your are right, the reflection is very high. but what...
this is the problem:
in the text book, gds of nmos can be calculated in two way, but i got results significant different
one is lamda*id, another one is an approximate expression :gds≈gm/100
next is how i calculated:
gm=β(Vgs-Vt);
and lamda in this way...
anyone can help me? Thx!
my active inductor's impedance in 2GHz is 1.103+j*463.194, so you can replace this circuit with a resistance and inductance in series. and the res is 1.103 Ohm with the inductance of 36.86nH.
now i put a cap(6.7809pF) on the input port like this:
the value of cap is...
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