In module generation for analog cell layout, it is necessary to incorporate the designers? empirical techniques to achieve small area as well as high performance. This paper presents the formulation of two types of module generation problems, faithful to expert?s empirical knowledge, to ease such incorporation. One is series module generation problem, where we introduce equivalent circuit modif ications to maximize the dif fusion merging and minimize the number of dif fusion contacts. The other is the common-centroid module generation problem which is formulated as a mathematical optimization problem taking coincidence, symmetry, dispersion and compactness into consideration. A greedy algorithm is also presented to solve this problem.