AbstractThis paper presents a simple simplification method to design a multistage amplifier. The simplification procedure is based on a defined criterion which mainly related to ignoring negligible terms. In order to verify the validity and accuracy of the exploited method, a complex four‐stage CMOS amplifier is considered. Simplified transfer function and circuit simulator output are compared. According to simulation results obtained from HSPICE circuit simulator and TSMC 0.18 μm CMOS technology, the proposed approach expresses a bitter performance by 1% error. The aim is to propose a preprocessing algorithm. This helps main algorithm to deal with simpler inputs. In this way, a preprocessing algorithm is investigated which reduces CPU time and needed memory to simplify heavy symbolical transfer functions. Since target is analog and mix mode circuit, some circuit‐based assumptions are considered.