How to judge which design is the most optimal?

[hdmi]

I am self learning the essence of the analog design. From a paper I am reading, it seems that even for a very typical folded cascode OP Amp, depending on the approach, they can have a very different transistor ratio (W/L) for the same transistor(table 5), and they still all meet the spec (table 4), this result makes me wonder that 10 designers might come up with 10 different solutions, all meet the spec. My question is then how to judge if one is better than the other, and how do I know what I have now is not good enough and still have room to improve? Also from a few text books and papers I read about the design procedures, they all seem to lead to only one solution, how would one come up with so many different feasible solutions?

 

[ricklin]

Optimal Design?

I think circuits meet the spec is circuit good enough. If the spec is too loose, than optimize the circuit to the direction which is cared the most.

 

[drDOC]

Re: Optimal Design?

My question is then how to judge if one is better than the other, and how do I know what I have now is not good enough and still have room to improve?

There is always room to improve. But you are good enough when you meet the spec.

How to judge: Well if one of the other nine designs burns less power, or uses less silicon area/less components then that seems to be a better design.

 

[pfd001]

Optimal Design?

power and area are the strandard for evaluate the design