FreePDK45 usage in Virtuoso

I downloaded the NCSU FreePDK45 to take a look. You should report this to NCSU because there's a problem with the data they ship.

In Setup->Model Libraries, you need to add (for example):

$PDK_DIR/ncsu_basekit/models/hspice/hspice_nom.include

(there are also files for hspice_ff.include and hspice_ss.include). However there is an error in these files for the 1.4 version of the PDK. In these include files there are lines such as this:

.inc '$PDK_DIR/ncsu_basekit/models/hspice/tran_models/models_nom/NMOS_VTG.inc
.inc '$PDK_DIR/ncsu_basekit/models/hspice/tran_models/models_nom/PMOS_VTG.inc

The quotation marks are not balanced (there's a missing quotation mark at the end of the line) so spectre fails because of the error. You need to fix them all to be like this:

.inc '$PDK_DIR/ncsu_basekit/models/hspice/tran_models/models_nom/NMOS_VTG.inc'
.inc '$PDK_DIR/ncsu_basekit/models/hspice/tran_models/models_nom/PMOS_VTG.inc'

(same for the rest of the lines, in all of the ff and ss files too).

Having done that, it runs OK in Spectre.

The documentation for the kit is rather sparse, to say the least. It doesn't even mention how to set it up for HSPICE.

Perhaps you should consider using gpdk045 instead from http://pdk.cadence.com ?

Andrew

I encountered another different error with standard cell.  What is wrong with XOR2 (I44) ?

I encountered another different error with standard cell.  What is wrong with XOR2 (I44) ?

The error is pretty clear - it can't find a schematic view to switch into. I just downloaded the ncsu-cdk-1.6.0.beta (which seems to be the latest) and it doesn't have schematic (or cmos_sch) views for any of the xor or xnor gates (it has them for many of the other logic gates). You could have seen this by looking in the library manager. It only has functional views - so your solution is either to create a schematic yourself, or do a mixed-signal simulation using AMS where you can use the functional view instead.

You might want to contact NCSU to see if they plan to do anything about this. I wouldn't have high hopes though since everything in the CDK is dated from 2007.

Andrew.

> It only has functional views - so your solution is either to create a schematic yourself, or do a mixed-signal simulation using AMS where you can use the functional view instead.

Create a schematics as in create the XOR gate from scratch using mosfets ?

What do you exactly mean by AMS simulation ?

kevin998x said:

Create a schematics as in create the XOR gate from scratch using mosfets ?

Yes.

kevin998x said:

What do you exactly mean by AMS simulation ?

Set the simulator in ADE to be "ams" (Setup->Simulator). However, if you don't know how to do that, that's beyond the scope of answering here. You'd need access to an INCISIVE or XCELIUM release which would need to be in your UNIX path, plus you would need to create a config view as AMS always needs a config. Then you would need to set up the connect rules so that it knows how to convert digital signals to analog and vice versa. If you're going to go down this route, I'd speak to your supervisor first.

You might be better off using gpdk45 instead of this NCSU PDK - you can download both the PDK and a standard cell library from http://pdk.cadence.com (although as a student, which I assume you are, you may have to go via your University Liaison/Professor to do that).

Andrew