We present a method for designing operational amplifiers using reversed geometric programming, which is an extension of geometric programming that allows both convex and non-convex constraints. Adding a limited set of non-convex constraints can improve the accuracy of convex equationbased optimization, without compromising global optimality. These constraints allow increased accuracy for critical modeling equations, such as the relationship between gm and IDS . To demonstrate the design methodology, a foldedcascode amplifier is designed in a 0.18 ?m technology for varying speed requirements and is compared with simulations and designs obtained from geometric programming. Categories and Subject Descriptors: B.7.2[Integrated Circuits]: Design Aids General Terms: Algorithms, Design
Johan P. Vanderhaegen, Robert W. Brodersen