need 7pF to 10pF at 2.5GHz

Status
Not open for further replies.
thank you very much for your kind guidance, Dr Volker. I Hope we can hire you as a consultant in the future. have a great day ahead.

- - - Updated - - -

i have another question. can we do design LTCC implementation in ADS?
 

mistake.. pls ignore

- - - Updated - - -

dr volker,
i have one last question. im getting different inductance when i simulate using a different set of formulas. Please let me know which one is correct and why?



results and formulas are attached side by side. the 1st formula is from ADS template.

- - - Updated - - -



ADS template have two method. extracting ind from Y11 and also Y12! both giving totally different results. Y11 shows -ve inductance whearas Y12 shows positive! which one to believe!

- - - Updated - - -
 

Attachments

  • 5.png
    94.6 KB · Views: 114
Last edited:

There is no "correct" or "wrong" equations, they are valid under certain conditions, as mentioned in the ADS template.

Assume you have an inductor represented by a pi model, with series RL and shunt C to ground. You can then extract the pure L from the series path (excluding shunt effects) or the effective series inductance (including the effect from shunt components), or the effective input inductance into one terminal when the other terminal is shorted. You then get 3 different curves. All are valid, just different what you consider "the inductance". So you need to decide what value is relevant for your design use.
 
pragash said:
View attachment 151691
Click to expand...

this inductor connected in series and not shunt to ground. Pure inductance and resistance extraction (Y12) shows +ve ind which is correct. shunt to ground inductance (Y11) shows negative inductance which is not my case.

- - - Updated - - -

pragash said:
View attachment 151690
Click to expand...

this is a differential measurement of the inductor using reactance (imag(Z)). its only valid for differential configuration which is also not applicable for me. the best is two port measurement.
 

pragash said:
this inductor connected in series and not shunt to ground. Pure inductance and resistance extraction (Y12) shows +ve ind which is correct.
Click to expand...

But your inductor has parasitics: capacitance to ground.

pragash said:
shunt to ground inductance (Y11) shows negative inductance which is not my case.
Click to expand...

That is possibly correct due to parasitics. Can you upload the inductor *.s2p, so that we extract the equivalent circuit model?

pragash said:
this is a differential measurement of the inductor using reactance (imag(Z)). its only valid for differential configuration which is also not applicable for me. the best is two port measurement.
Click to expand...

I agree that you should use the full S2P data in circuit simulation. I just tried to explain why there is more than one correct answer regarding "the inductance value".
 
I think the problem is not considering the prerequisites of ADS distributed components. MSIND is a microstrip inductor, it's referring to a MSUB microstrip substrate definition creating a respective shunt capacitance. Reading the ccdist manual thoroughly should clarify everything.

Place a lumped inductor, e.g. AIRIND1 model and both setups should give equal inductance.
 
Can you upload the inductor *.s2p so that we have a useful data basis for discussion?
 
Dr. Volker,
actually, I don't know how to generate an s-parameter file from the ADS. due to that, i sending you my coil parameters. you can simulate it and get the S-parameters. sorry for the inconvenience caused.
 

Data starts at 2.3GHz, which is not enough to extract a model. Please provide wideband data that goes down to DC.
 
Indeed, your inductor has enough shunt capacitance to ground to become capacitive in some port configurations. Here is a simple pi model, extracted from your S2P:


.subckt SON3_38 1 2 REF
C_C1 1 REF 0.109335pf
C_C2 2 REF 0.105086pf
L_L1 1 3 63.69988nh
R_RL1 3 2 1.0e-5
.ends SON3_38

If we evaluate Y11 (port 1 input impedance with port 2 shorted to ground) it looks capacitive at high frequency because we then have 63.7nH || 109fF.
If we use the differential port configuration, we have a higher SRF because then 63.7nH || (109fF in series with 109fF)


 
Dr Volker, how did u extract the exact C associated with the coil?
 

pragash said:
Dr Volker, how did u extract the exact C associated with the coil?
Click to expand...

I went the easy way and used the Sonnet PI model extraction.
You should be able to get a similar answer in ADS by extracting the shunt path elements. For your convenience, I have posted some code from my Inductor Toolkit model extraction.

Y = stoy(S)
omega = indep(S) * 2 * pi
Cshunt_port1= 1 /(-omega*imag(1/(Y(2,1)+Y(1,1))))
Cshunt_port2= 1 /(-omega*imag(1/(Y(2,1)+Y(2,2))))

 
Last edited:
Reading these makes me sad about my job. How can I find people/material to help me learn about these stuff?

I am currently suffering from a similar phenomeon on extracting the parasitic values of (lumped elements+TLIN) in matching circuit. I need to model my elements and TLIN's in a better way; but have no clue on where to start.
 

what is the best impedance we should design the interconnect so that it won't form an inductor? 50ohm? or 75ohm?
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…