The Designer's Guide Community Forum
https://designers-guide.org/forum/YaBB.pl Design Languages >> Verilog-AMS >> chain of mosfet in verilog-A https://designers-guide.org/forum/YaBB.pl?num=1181642337 Message started by Darius on Jun 12th, 2007, 2:58am |
Title: chain of mosfet in verilog-A Post by Darius on Jun 12th, 2007, 2:58am Hello!!! This website is wonderful! I'm working with a "chain" of mos and I created a module for the instance of child model like this: mos m1 (.g(gate), .d(d1), .s(source)); mos m2 (.g(gate), .d(d2), .s(d1)); mos m3 (.g(gate), .d(drain), .s(d2)); but : 1)how to plot the outputs of single mosfet like each gate current or charges? 2)how is possible to decide from simulator netlist if to connect 2 or 3 mosfets in the chain?(I'm thinking about if or case statement but this block is outside the "analog begin" and this solution doesn't work. Please, can you help me? Best Regard to all! Darius :) |
Title: Re: chain of mosfet in verilog-A Post by Geoffrey_Coram on Jun 12th, 2007, 4:07am Darius wrote on Jun 12th, 2007, 2:58am:
This is a simulator-specific implementation detail; your simulator may or may not provide access to that information, and you'll have to read the documentation to find out how to get it. Quote:
I think what you want is presently not possible within the language (there's ongoing work in the committee to permit the "generate" construct to do this). However, you might be able to get similar behavior by setting up the chain for the longest length you might want, and then use a parameter to select how to short out the chain. Code:
If short_to == 2, then d2 will short to source, and only "m3" will be active. If short_to == 0, then the LRM specifies that the default for the branches is zero flow, meaning that there are no shorts, and the current has to flow through all 3 mosfets. |
Title: Re: chain of mosfet in verilog-A Post by Darius on Jun 12th, 2007, 10:13am Darius wrote on Jun 12th, 2007, 2:58am:
I use simucad smartspice version 2.24.3.R and I didn't find yet this property in the documentation. I have also convergence problem with chain for gate voltage>0.8, it's possible to be a problem because I use a chain? I'm not able to reach it. Tank'u for reply, second answer is a smart idea ;) Best regard Dario |
Title: Re: chain of mosfet in verilog-A Post by Geoffrey_Coram on Jun 13th, 2007, 6:01am Darius wrote on Jun 12th, 2007, 10:13am:
Very strange! I assume you can make the same chain in a regular spice netlist; does it work there? |
Title: Re: chain of mosfet in verilog-A Post by Darius on Jun 14th, 2007, 5:57am Darius wrote on Jun 12th, 2007, 2:58am:
I tried to do the same chain in regular spice netlist but I don't know how to do... My code is Code:
I think it's bad, I don't have many experience ... I tried also to do the verilog chain with another mos module and it work, so it can be that my module have some problem? |
Title: Re: chain of mosfet in verilog-A Post by Geoffrey_Coram on Jun 15th, 2007, 5:15am Darius wrote on Jun 14th, 2007, 5:57am:
Seems likely to me. Did you try running some basic i-v curves on the module that has problems? |
Title: Re: chain of mosfet in verilog-A Post by Darius on Jun 15th, 2007, 6:08am Geoffrey_Coram wrote on Jun 15th, 2007, 5:15am:
Yes, the module works regularly alone. With chain it doesn't reach the convergence of intermediate nodes voltages. But the code for the spice chain has some problems? :'( |
The Designer's Guide Community Forum » Powered by YaBB 2.2.2! YaBB © 2000-2008. All Rights Reserved. |