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Modeling >> Semiconductor Devices >> Sentaurus AC Simulations
https://designers-guide.org/forum/YaBB.pl?num=1458009379

Message started by Dinis Cheian on Mar 14^th, 2016, 7:36pm

Title: Sentaurus AC Simulations
Post by Dinis Cheian on Mar 14^th, 2016, 7:36pm

Hi,

I am using Sentaurus to perform a simple AC simulation on a PN junction. I have an Anode terminal and a Cathode terminal and I am interested in obtaining I(Cathode)/V(Cathode) as a function of frequency in order to find the 3dB bandwidth.
The simulation seems to converge but the parameters that it spits out is are a(1,1) and c(1,1) which is are defined as:
I=A*V+i*omega*C*V
where:
I- small signal current
V- small signal voltage
omega - 2pi * (operating frequency)
i - imaginary unit
So it looks like if I do sqrt(a^2+(2pi * (operating frequency) * c)^2) this should be I/V as a function of frequency. However what I get is a function increasing with frequency that looks nothing like a single pole system.
Does anyone know how to solve the problem?
I've already tried:
1. Using simple transient simulation to find the bandwidth (that works but I want the AC simulations).
2. Tried to use the RF library in SVisual to extract the Y matrix but that library only works for 2 ports i.e. 3 terminal devices.

Any help would be greatly appreciated.

Thanks,
Dinis

Title: Re: Sentaurus AC Simulations
Post by ULPAnalog on Mar 14^th, 2016, 9:54pm

Hello

It looks to me as if you are looking at the junction capacitance in your analysis. For a capacitor I = jwCV, with all the symbols carrying their usual meaning. And indeed the current increases with frequency (true for a RC load). You might want to revisit what you would like to define as -3dB bandwidth.