Gds2 file format

GDSII is an integer database. The basic unit of measurement is a nanometer 10 -9 meter. Since four byte signed integers are used to describe a coordinate then the integer coordinates can range from from minus 2 31 to plus 2 31 GDSII is organized in a hierarchical fashion. That is to say, that a number of elements are grouped into a cell or structure, and then that structure is used or instanced or placed many many times. Since digital IC's are extremely repetitive, the database matches the physical layout approach very efficiently.

The fifth data type is the "Four-Byte Real". This is the one that seems to have never been used, so I'll describe the eight byte real in a bit more detail. The sixth data type is the "Eight Byte Real". This one gets a little more use. The first most significant bit of the first byte is the sign, one means negative, 0 means positive. The 7 least significant bits of the first byte are the exponent in "excess 64" notation.

You must subtract 64 to get the true value. I'll show the subtraction in the formula below. The remaining 7 bytes are the mantissa, with a binary point to the left of the most significant figure. The formula below uses the unsigned integer value of these 7 bytes as the numerator of a fraction.

The length of this string is always equal to the length of the record minus the four bytes used for the record header. If this number is not even, a NULL character 0x00 is added to the end. This is another artifact of the 16 bit words that the stream file format assumes. The records shown within square brackets '[]' are optional. The or bar ' ' indicates one or the other. Sort of an "include" element. I haven't seen this since the days of 9 track tapes on reels, but just in case, here we go If memory serves, Calma DOS allowed 6 characters in a file name, with a 2 character extension.

To calculate the size of a user unit in meters, divide the second number by the first. To convert scale-independent text elements as well, select a non-zero default text size value for this option in the setup. By default the Save Text as Polygon option is turned off. A polygon exceeding this limit will be split by default. However it is possible to save such large polygon in multiple blocks. This method will allow an unlimited number of polygon points. The names of the layers and its appearance in the design is not stored.

This is done by adding an additional cell to the design with the name 'LayerNames' that contains a text elements on each layer with the layer names. Colors, and style of the layer are stored as attributes of the text element. If this option is activated, that additional cell will not be visible in the LayoutEditor. However, it will not interference with any other GDSII tool as long as no cell with the mentioned named is used in the design. A file validation is performed after any save operation.

This is done by calculation a SHA1 checksum during the save process. This checksum is validated for the stored file in a second step to ensure that the GDSII file is correctly stored. We need different [approx 18 msks] for a typical CMOS process. These files can not be read as they are of not readable format. GDS files are mainly for fab purpose. All the best. GDSII is a file which is actually ment to be sent for fabricatin which has layout information..

Follow the link and know more. Thanks Regards Shankar. Click to expand Coolwater Newbie level 1. Last edited by a moderator: Sep 16, Similar threads G. How to open.