Diode Modeling by VHDL-AMS

[electronics_sky]

vhdl-ams+examples

hi there,

I would like to build a behavioral diode model for my simulation by using VHDL-AMS. It don't need to be very close to SPICE model.

At first, i modeled it by using "Idiode == Iss(exp(Vdiode/n*VT)-1)" in VHDL-AMS and found "convergence problem" during simulation when using in a Charge Pump simulation. I suspected the convergence problem is due to the overflow of exponential part. Can anyone advice how to produce an algorithm to limit the overflow of the exponential part as what usually do in Verilog-AMS "limexp()" function. FYI, Verilog-AMS description should be "Idiode(p1,p2) <+ Iss(limexp(Vdiode(p1,p2)/n*VT)-1)".

By the way, can anyone suggest an even simpler model/ more direct model by using only battery, resistor and etc to the operation of diode.

Please kindly provide any documents, URL and etc for understanding purpose. Thank you very much.

 

[erikl]

vhdl ams manual

Please kindly provide any documents, URL and etc for understanding purpose. Thank you very much.

Check the diode examples in the document below.

 

[electronics_sky]

diode modeling

hi erikl,

Thank you for your reply.

By the way, anyone mind to share the method by using VHDL-AMS. I found a solution from **broken link removed**.

However i don't understand its algorithm to overcome overflow problem, expecially,

if abs_x < 100.0 then
result := exp(abs_x);
else
result := exp(100.0) * (abs_x - 99.0);
end if;

I had implement it but the convergence doen't seem to improve.

Anyone mind to point out or provide more insight about how to model a diode by using VHDL-AMS to prevent overflow problem.