Geometric Programming (GP) has been employed in automatic design of analog integrated circuits. Its major advantage is the ability to find the globally optimum solution to a problem. It however, suffers from dependency on the accuracy of the initial equations and the parameters used in these equations. This, in circuit design, causes discrepancies between GP predictions and simulation results - especially in sub-micron devices - thus resulting in a non-globally optimum circuit design. In this paper, two major sources of this discrepancy are introduced and resolved by an iterative simulation-equationbased design methodology based on GP for operational amplifiers. In order to show the effectiveness of the methodology, it has been applied to two op-amp architectures.

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