Capacitor inditance and resistence

[tadeupasetto]

Hi, i'm trying to simulate an phase shifter using a varactor and I need to know how I can estimate the inductive and resistive efects for a capacitor.

 

[Phytech]

Capacitor inductance normally modled in series with Capacitor, its values differs for different capacitor configurations, e.g. lead ap has big inductances (up to a few nH), while chip caps have low inductances (fraction on nH). For chip caps, it also depends on how do you mount the chips and the amount of solders used.

Capacitor resistance is directly related to the capacitor Q. Here you can model it either a R in series with C or a R in parallel with C. You can get the value easily if you know the capacitor Q. You can deduct the formula yourself. Based on the model (either with Rp or Rs, write the expression of Z, then Q equals the imaginary part of Z devided by the real part of Z, solve for R and R is a function of Q, f, and C.

 

[kspalla]

In ADS u can model it if you have clear definition of the varactor device.

 

[tadeupasetto]

Now, I'm using the varactors avaiable in the Ansoft Desinger, like MV2105 and MMBV105GLT1, but the results of simulations and the practical results are very different. I'd like to know if I need to make same corrections in these models.

thank's