This paper reports a system design method of high-frequency class-D inverter for wideband current control for robotics in human society. There is a problem that conventional inverters are restricted by a switching frequency and hence the motor can not drive in a high-frequency range. Since a control system requires a severe condition as for a phase lag, such restriction should be removed. To overcome this problem, the paper designs a system with providing three pillars: a controller to attain a robustness, hardware improvement and a modulation technique to increase a bandwidth, and design policy for a processor to treat a high-frequency signal. Then, a GaN-HEMT-based class-D inverter and an FPGA-based controller are prepared to support these pillars. The paper proves an importance of the integrated design.