Small current measurement module for eliminating bias voltage error through commutation

The utility model aims to provide the small current measurement module for eliminating the bias voltage error in the commutation mode, which can judge the current direction and reduce the influence of line noise on current signals. The circuit comprises a sampling resistor, an operational amplifier, a first analog switch, a second analog switch, a third analog switch and a fourth analog switch, the input end and the output end of the sampling resistor are connected in a loop to be tested, and one end of the first analog switch and one end of the third analog switch are both connected with the first sampling end of the sampling resistor. The other end of the first analog switch and the other end of the third analog switch are connected to the positive input end and the negative input end of the operational amplifier respectively, and one end of the second analog switch and one end of the fourth analog switch are connected with the second sampling end of the sampling resistor. The other end of the second analog