Restriction on RAM size on Chip

[eng.obd_md]

Hi,

I have a simple question, is there any restriction by technology vendors or fabrics on the size of Ram integrated on an ASIC chip? I mean can they be as big as the one want?

Cheers

 

[artmalik]

Rams are designed for speed so a very big ram will not make sense because the design has to work for an optimal power/area/performance. there is always a limit on the number of bitcells that you can have in a ram. But yes there is usually a limit a number of bits you can have on a chip which is usually very large.

 

[jbeniston]

No, you can have all the chip be RAM if you want (apart from I/O pads, of course). These are generally called RAMs rather than ASICs though

In practice, some memory compilers used for typical ASICs will have size limitations, but you can get around this by combining multiple instances or designing the RAM by hand.

 

[artmalik]

The first statement is not true that you can have any amount RAM in an ASIC chip. There is a limit based on number of bits you can have on a chip. This is something based on the yield of the design. By RAM we are talking about about embedded SRAM. This is in newer technologies like 28nm/20nm.