The proposed low-cost, scalable, synthesizable Voltage-Frequency Adjustor (VFA) design provides voltage and frequency automatic adjustments for implementing low-power systems. This design is effective in reducing power consumption from managing the supplied current and clock frequency for the structurally dynamic varying systems. The VFA supplied electrical current amount and voltage level are automatically adjusted from sensing the voltage drop of the fanout load. This adjustment mechanism controls the activated power switch quantity to allow a structure varied design that can obtain a stable fanin voltage level, regardless of the designed module that is dynamically added or removed from the system. Compared to the conventional dynamic voltage frequency scaling technique, the VFA is cost effective and can be easily integrated with the target design as a single chip. The experimental results show that the combination of VFA chips and an H.264 video decoder is successfully validated with 49%∼68% power reduction compared to the case that the H.264 video decoder directly uses an outer power supply.