Systematic generation of transconductance based variable gain amplifier topologies

A systematic method for the generation of variable gain amplifier topologies is proposed. The generation is based on voltage controlled current sources (VCCSs) modelling saturated MOS transistors, resistors or combinations of these elements. It is shown that many alternative circuit topologies can be generated, that would not easily have been found in an intuitive way. Simulation results shown that significant differences in performance occur, with various mixes of specific strong and weak points. The set of alternative topologies can be used as a circuit topology database for analogue CAD systems.