Abstract: In high-precision applications，the control accuracy of the servo system is extremely high required.

The control precision of the servo system depends largely on the precision of the feedback measurement. Position

and speed feedback accuracy can be improved by increasing the absolute accuracy of the encoder，and it is not

sensitive to external interference，while the current sampling link is more sensitive to switching noise，which will

cause torque fluctuation and reduce the control precision of the servo system. Based on the principle of highprecision current sampling in servo system，the influence of switching noise on current control accuracy was studied.An SINC3 filter structure with continuous output and a method to improve the steady-state current control accuracy were proposed. The experimental results show that the method has obvious effect on restraining the current fluctuation caused by switching noise，and has strong engineering guiding significance.

      Key words: current sampling；control precision；switching noise；torque correction