• A. CIF to Cadence
• B. Cadence to CIF
• C. Notes on CIF format
• D. STREAM to Cadence and Cadence to STREAM (GDSII)

A. CONVERTING  A CIF FILE TO CADENCE DATABASE FILE

1. Suppose that you want to convert a Mosis standard frame which you have located on the MOSIS Homepage. View the mosis std file that is to be downloaded using Netscape first. Obtain the Top Cell Name before saving the file in your preferred directory. Save the cell in your directory. To obtain the Top Cell Name, check the name that is present in the file, below the scaling factor:
 

e.g. DS 1 1 1; (scaling factor)

        9 CV;

2. Go to the CIW window and select Translators -> Physical -> CIF IN. You will  have to supply the following information:
 

Template File: A file containing info/fields which remains constant everytime you call up a CIF process. Not important. Leave blank.

Run Directory: Designated directory of converted CIF files.

Input File: Name of CIF file - e.g CV2.cif

Top Cell Name: Same as above - e.g CV (see NOTE 2)

Output: Opus DB

Library name: Name of library where cells are stored

ASCII Dump File: Leave blank

ASCII Tech File Name: Tech file that you wish to use. Preferably the same as the one used to create your other libraries.

Scale UU/DBU: Depends on the type of technology process the CIF file uses.
 

The scale is found from the formula: UU/DBU=0.01/lambda
 

Examples:

a. 0.6um  technology - use scale 0.033333333.. (lambda = 0.3)

b. 0.8um technology - use scale 0.02 (lambda = 0.5)

c. 1.2um technology - use scale 0.016667 (lambda=0.6)

e. 1.6um - use scale 0.0125 (lambda = 0.8)

e. 2.0um - use scale 0.01 (lambda = 1.0)

Units: microns

Hierarchy Depth Limit: 20

Cell Name Map Table: Leave blank

Layer Map Table: Use a suitable layermap.mosis

Click OK.

NOTES:
 

1. If you are trying to CIF in a complex structure comprising of many  different cells, then to find the Top Cell Name -> go to the penultimate line of the CIF file and find out the number next to "C" :
 
e.g C 150

Then try to find the line which contains " DS 150 1 1 " as an example.

Note that the scaling factor " 1 1 " could vary from file to file.

The line below it should contain the Top Cell Name.
 

e.g DS 150 1 1;

      9 ENIAC;

Save the file as CV2.cif or somewhere along those lines.

2. The cellname cannot be the same as the fileame; in that case the conversion will not work. Change the name of the file or the topcell name.
 

1. In Cadence, CIW Window, Select Translators -> Physical -> CIF Out

The important fields are:
 

Run Directory: Where the CIF file is to saved

Library Name: Library in which cell to be CIFed out is located

Top Cell Name: Name of cell e.g CV (see NOTE 1)

Output file: filename.cif

Scale UU/DBU: Same as the ones used in CIF In.

Layermap Table: Same as the one used in CIF In.

Click OK.
 

NOTES:
 

3. It is interesting to note that the Cadence CIF_out operation does not output the line C# (see also the Note 1 in the section above on CIF in).As a result Mosis will reject the cif file at project check if the file was submitted without the C# at the end (see also submitting a CIF File).

4. Before submitting a cif file, it is always good to check it to make sure that all the layers have been converted and that the dimensions are correct (see CIF format below). In addition, read in the cif file back into Cadence and check whether the design is the same as the one you converted it from.

The cif file is text file that can easily be checked. The dimensions in cif are in hundreds of a micron. The line that starts with DS gives the scale:
 

DS 1 a b

in which a/b is the scale.

The lines underneath gives the layername followed by a symbol that indicates the geometry and the dimensions. For example a rectangle

will be specified by a "B" as follows:
 

CCA B #1 #2

in which #1 is the width (X) and #2 the hight (Y). The actual dimensions in micron are than found as follows: width of box in um:
 

#1 * (a/b) / 100

Ex.

DS 1 35 100

CCA B 200 200

is a contact window to the active (CCA) of dimensions:
 

200*35/100*1/100 = 0.7um.

This process is similar to converting CADENCE DATABASE FORMAT to CIF or vice versa.
 

1. Go to Translators -> Physical -> Stream In/Out depending on what is needed.

2. Enter all the fields with the appropriate names and values.

 As for the UU/UDB scale, leave the default value of 0.001

3. For Stream in, the output filename must have a postfix .gds.
 

e.g filename.gds

4. Note that the layermap used in this process is different from that of CIF. A different layermap with the proper layer names and corresponding GDSII numbers has to made.