Analog module placement realizing symmetry constraints based on a radiation decoder

This paper presents a new hybrid simulated annealing (SA) and genetic algorithm (GA) approach to analog module placement. The bit-matrix chromosomal representation is employed to describe the location and orientation of modules. Compared with the conventional bit-string representation, the proposed chromosomal representation tends to significantly improve the search efficiency. In addition, a radiation decoder is developed to transform an absolute coordinate placement of modules to a relative placement. In this way, the symmetry constraints imposed in analog circuits can be easily implemented in the placement run. Use of this decoder can also drastically shrink the configuration space without degrading search opportunities. The algorithm has been tested with several benchmark circuits. The experiments show this promising algorithm makes the better performance than simpler SA or GA approaches with the satisfactory results comparable to manual placement.