THE VLSI DESIGN PROCESS : A typical analog design flow is as follows.....

A typical analog design flow is as follows:

In case of analog design, the flow changes somewhat.

• Specifications
• Architecture
• Circuit Design
• Simulation
• Layout
• Parametric Extraction / Back Annotation
• Final Design
• Tape Out to foundry.

 

While digital design is highly automated now, very small portion of analog design can be automated. There is a hardware description language called AHDL but is not widely used as it does not accurately give us the behavioral model of the circuit because of the complexity of the effects of parasitic on the analog behavior of the circuit. Many analog chips are what are termed as "flat" or non-hierarchical designs. This is true for small transistor count chips such as an operational amplifier, or a filter or a power management chip. For more complex analog chips such as data converters, the design is done at a transistor level, building up to a cell level, then a block level and then integrated at a chip level. Not many CAD tools are available for analog design even today and thus analog design remains a difficult art.