Macros

Macros:

• Macro can be considered as an IP(Intellectual property)
• Macro Cells are the Memory cells. These IPs have been designed by some other Analog design team (A vendor generally sells the macro as a product. so it has be generic enough to support different products), which can be used in the floor plan stage of the design.
• It can be soft macro which is RTL code or hard macro which is synthesized code.

Soft macro:

• Soft macros are more flexible in terms of redesign. Soft macros are defined in Synthesizable RTL.
• This RTL doesn’t depend on any technology, so Soft macros are not specific to any manufacturing process.
• Soft macros are editable and can contain standard cells, hard macros, or other soft macros. They can be reconfigured or modified if necessary.
• Using Soft macros in the design is a risk factor because of it being somewhat unpredictable in terms of performance, timing, area and power.

Hard macro:

• LEF, GDS2 file format allows easy usage of macros in different tools.
• Hard macros are generally in the form of hardware IPs, Hard macros are targeted for specific IC manufacturing technology.?
• ?Hard macros are very similar to block level designs, which are optimized for power, area, timing and silicon tested.
• ?While accomplishing physical design it is possible to only access pins of hard macros unlike soft macros which allow us to manipulate the RTL.
• While placing hard macros, we can only move, rotate, flip but we can’t touch anything inside hard macro.
• Before using hard macro be aware of features and characteristics of hard macro, other than power, timing and area you also should know pin properties like sync pin, I/O standards etc.

Firm macro:

• Firm Macros are defined in Netlist.
• These are optimized for PPA using a specific fabrication technology.
• Firm macros are more flexible and portable than hard macros.
• Firm macros are predictive of performance and area than soft macros