This article presents the analysis of the efficiency of two control systems used to regulate the DC voltage in an implanted device fed by an inductive power link. Both control systems work outside the body, eliminating the voltage regulator in the implanted circuit (inside the body). These ways of voltage control reduce the power and heat dissipated inside the body. The first control system involves regulation of power supply voltage to the high frequency amplifier. The second control system adjusts the frequency of the inductive link. A laboratory prototype was built and experimental results were obtained. It is shown that for a range of distance between 0 mm and 11.8 mm the efficiency of the system is greater when using amplitude voltage control. Above that distance, the efficiency of frequency control is better. A difference of 20% was obtained in the optimal points.