Application Specific Integrated Circuit. An ASIC is a custom IC. You might make an ASIC because:
- You need a chip that isn’t available off-the-shelf,
- You can save money by merging a lot of components into one,
- Recently, for fun!
If your design only needs digital logic, you might be able to use an FPGA. An advantage of ASICs is that they can combine digital and analogue circuits together in one chip. A disadvantage is that errors often cannot be fixed afterwards, hence the heavy use of verification.
Big semiconductor companies produce millions of chips, which can offset the large costs related to the masks. For example, a full maskset for the 130nm process at the Skywater foundry costs about $200k.
Until recently, an additional cost was the license fee for the ASIC software tools. Now we have the open source tools like OpenLane that have opened the door to experimentation and learning.
Here’s a picture from magic showing a layout of my VGA clock
And a zoom, more clearly showing the standard cells
I didn't know what to expect regarding formal verification and that was delightful, I thought it was very fun and totally new to me.