An apparatus for current measurement, comprising: a magnetic ring, through which can pass at least one conductor for passing a current to be measured; a coil wound around said magnetic ring; a sampling resistor, that produces a first feedback signal, which may be a voltage signal, wherein a first end of the sampling resistor is electrically connected to a first end of said coil, so that the sampling resistor is connected in series with said coil and a second end of the sampling resistor is connected to earth; a driving voltage source, with an output end thereof being electrically connected to another end of said coil, the driving voltage source having an adder; a comparator, with an output end thereof being electrically connected to a first input end of said driving voltage source being a first input end of the adder; a first feedback unit, wherein an input end of said first feedback unit is connected to the first end of said sampling resistor for acquiring the first feedback signal from said sampling resistor, wherein an output end of the first feedback unit is electrically connected to another input end of said adder for providing the first feedback signal to said driving voltage source; a detection circuit for acquiring the first feedback signal from said sampling resistor to obtain a current signal (i) measured thereby, characterized in that, the apparatus further comprises a second feedback unit having a differentiator, wherein an input of said second feedback unit is connected to the first end of said sampling resistor to acquire the first feedback signal from said sampling resistor to process the first feedback signal by the differentiator and to generate a second feedback signal via an output end of said second feedback unit, wherein an output end of said second feedback unit is connected to an input end of said comparator, wherein a first preset value and a second preset value are set in said comparator, the second preset value being greater than the first preset value, the first preset value controlling the output polarity of said driving voltage source, such that the reverse point of the output polarity of said driving voltage source is set in a saturation region of said magnetic ring, and said second preset value is used to prevent said driving voltage (U e2) from being reversed in the remaining time domain, except the one where the first preset value was used, and wherein the output voltage (U e3) of said comparator is a square wave voltage with a fixed amplitude. a magnetic ring, through which can pass at least one conductor for passing a current to be measured; a coil wound around said magnetic ring; a sampling resistor, that produces a first feedback signal, which may be a voltage signal, wherein a first end of the sampling resistor is electrically connected to a first end of said coil, so that the sampling resistor is connected in series with said coil and a second end of the sampling resistor is connected to earth; a driving voltage source, with an output end thereof being electrically connected to another end of said coil, the driving voltage source having an adder; a comparator, with an output end thereof being electrically connected to a first input end of said driving voltage source being a first input end of the adder; a first feedback unit, wherein an input end of said first feedback unit is connected to the first end of said sampling resistor for acquiring the first feedback signal from said sampling resistor, wherein an output end of the first feedback unit is electrically connected to another input end of said adder for providing the first feedback signal to said driving voltage source; a detection circuit for acquiring the first feedback signal from said sampling resistor to obtain a current signal (i) measured thereby, characterized in that, the apparatus further comprises a second feedback unit having a differentiator, wherein an input of said second feedback unit is connected to the first end of said sampling resistor to acquire the first feedback signal from said sampling resistor to process the first feedback signal by the differentiator and to generate a second feedback signal via an output end of said second feedback unit,