Diode+capacitance+conduactance in ADS

[nassim1]

what you mean by diode

Hell all,

pls, can someone tel me how can we draw capacitance and conductance of diode in ADS soft.

the diode is modeled with spice model...

thank you in advance

N

 

[jayce3390]

25 a diode

You can do in this way :




put Vdiode around 0.5V typically

 

[nassim1]

diode capacitance

Thank you jayce3390,

why the diode is reversed ?

what do you mean by RP1 ?

how you have gotten the expresssion?

could you pls give me more information about the cicruit and equations ??

thank you in adavance,

N

 

[nassim1]

advanced design system & setting diode model

NO IDEA ??

 

[Soben]

capacitance in ads

Assuming you do not have access to the spice model otherwise things are easier.

The diode is in reverse since any diode (especially varactors) exhibit the higher capacitance range in reverse bias. Forward bias your capacitance is tinny.

Assuming your diode is a black box, it will have an effective real part (Resistance) and effective reactive part (Capacitance) at any frequency. Therefore the impedance of your diode is given as:

Z11=R+1/(j*2*pi*f*C) where C is your effective Capacitance

therefore if u you know Z11 then you can calculate C as:

C=-1/(2*p1*f*Imag(Z11))

since Z11=1/Y11 you get the equation jayce3390 gave you.

For the real Part you do the same, RP1 is the real part of the effective impedance of your diode.

So set up an S parameters simulator like the one jayce3390 gave, calculate Z11 or Y11 and then use his equations to calculate the effective capacitance.

The effective capacitance is not the real capacitance of the diode especially at higher frequencies. That is because the package parasitic inductances affect your capacitance value.

 

[nassim1]

Many thanks soben for explanation........

i will try the circuit that jayce gave me (thx jayce),

Nassim