An Improved-Precision Voice Coil Motor Drive Method Utilizing Additional Current Feedback

A new method using an additional current feedback loop with programmable gain amplifier (PGA) to improve accuracy and suppress output current drift is proposed for the analog drive architecture applied to high-precision small-current type voice coil motor (VCM). First of all, a gain switching method based on heuristic algorithm in the additional current feedback loop is proposed to cut down on the switch times and improve dynamic performance; Secondly, a tracking differentiator is utilized to suppress noise and flashes in current sample process, improving the robustness in the additional feedback ring. Finally, a VCM driver is built, and the performance is tested. In the range of -1mA~+1mA, an absolute accuracy of 5μA is achieved; in the range of 0~+35mA, the linearity is higher than 0.02%, which proves the effectiveness of the proposed method.