spiral inductor simulation - ADS Momentun

hello,

I am trying to design a spiral inductor in agilent ADS momentum. I took the MRIND element and attached differential ports to it , defined a mesh and simulated it from 1GHz to 10 GHz. but i am getting a very low value of L(in pH) and Q (<1)
i am also getting a very large resistance R ~ 50 ohm to 100 ohm from 1 to 10 GHz . the inductor dimensions are 50 um by 50 um No of turns = 1 w = 4 um .

can anyone please help me with this? i am new to momentum and i am not able to get this right..

thanks..

What is the mesh frequency value? You have to set the maximum frequency of the S simulation i.e 10GHz.

How do you compute L value? From S11?

it was 5 GHz ..i'll change it to 10 GHz..
thanks a lot..

btw..can you please tell something about substrate definitions..i think i might be wrong there..thanks..

i computed L from S11 using
y = stoy(s) to get y parameters
and L = imag(1/y11)/(2*pi*f)

did you define a conductor layer between your substrate and free space ? (using "strip")

You must see 3 layers in the substrate definition such as ground plane, substrate and free space.

hey jayce..sorry for late man..

i saw the conductor defination(strip)... the conductor was defined as perfect conductor -
i changed it to conductor(impedence) and defined the value of impedence as 0.007 ohm per square - is that right? or should i be using perfect conductor?
thanks

With perfect conductor metal assignment, you should get similar result regarding to real conductor definition.

I would try strip conductor (sigma) and 4.1e7 siemens/m, this is copper.

Finally, getting inductance in the pH range could be real. Why did you think was small?

ok i'll use copper..
inductance is ok..its the (Q < 1) that bothers me..

IF Q factor is too low, your losses are high.
What they are ?
Substrate losses, conductor losses and Eddy losses.
Double check your substrate definition and layer structure..

@jayce and bigboss: thanks guys for your help..i think i got it right now..
i changed layer and substrate definations to cond - copper and MSUB1...and i am getting a Q of about 5..

btw, i am trying to make a transformer now..if i make another inductor on a higher layer, i should be able to do my thing right?
thanks..

btw.. i read from momentum tutorial that MSUB1 should not be used for momentum..it gives inaccurate results..so now i am using a predefined silicon substrate..

Hi Kjha, How are you feeding predefined silicon substrate defination. May I get the details of substrate and metal layer info.

@dgrke:
this link might help: Substrates in Momentum - ADS 2009 - Agilent EEsof Documentation Center