This chapter discusses the optimum design for a system with an energy transducer and voltage multiplier. An equivalent circuit model is presented to help identify the relationship between the circuit parameters and the output voltage/current characteristics of the system. A maximum power point is then identified. When the parasitic capacitance in the charge pump is significant, the optimization can be expanded. Section 3.2 discusses the maximum output power point using an equivalent model. Section 3.3 validates the model by comparing it with the SPICE simulation results. This paper discusses the relationships among TEG electrical parameters, the power efficiency of converters, and the power consumption of loads in autonomous sensor modules. Based on the method discussed, one can determine the total number of TEG units together with the number of TEG arrays and the number of TEG units connected in series per array when the characteristics of the TEG unit, the minimum temperature difference in operation, the power conversion efficiency of the converter and the load conditions are given. A practical design flow to minimize TEG cost is proposed and demonstrated, taking the maximum open-circuit voltage of the TEG and the dependence of the power conversion efficiency of the converter on the input voltage of the converter into consideration. The entire system, including a TEG and a Dickson charge pump converter, which were designed through the proposed flow, was validated with SPICE.