Verification of analog circuits is becoming a bottle-neck for the verification of complex analog/mixed-signal (AMS) circuits. In order to assist functional verification of complex AMS system-on-chips (SoCs), there is a need to represent the transistor-level circuits in the form of abstract models. The ability to represent the analog circuits as behavioral models is necessary, but not sufficient. Though there exist languages like Verilog-AMS and VHDL-AMS for modeling AMS circuits, there is no easy method for generating these models directly from the transistor-level descriptions. This thesis presents an improved method for extracting behavioral models from the simulations of AMS circuits. This method generates labeled Petri net (LPN) models that can be used in the formal verification of circuits, and SystemVerilog models that can be used in the system-level simulations.