High-precision current sampling circuit and method with nearly lossless interior of chip

The invention provides a high-precision current sampling circuit and method with the interior of a chip close to be lossless. The circuit comprises a metal sampling resistor Rsample, a switch sw1, a switch sw2, a trimming resistor Rt1, a trimming resistor Rt2, a resistor Rt, an operational amplifier OS, an MOS tube Mo, a resistor Rsnsout and a trimming module trim. Wherein the metal sampling resistor Rsample is a top-layer or secondary-top-layer metal resistor in the chip. High-precision current sampling is realized by utilizing the metal resistor in the chip and adopting a parallel sampling mode, the metal sampling resistor Rsample is a top-layer or secondary-top-layer metal resistor in the chip, so that the area below the metal resistor can be normally utilized, the problem of wasting the area of a silicon wafer can be solved, and the chip is simple in structure and convenient to use. Meanwhile, the resistance value of the metal resistor can be made as small as possible, and high-precision current sampling