Active RC filter and resistor array and calibration circuit thereof

The invention provides an active RC filter and a resistor array and a calibration circuit thereof. A calibration circuit for an active RC filter, the active RC filter comprising an array of resistors, the calibration circuit comprising: a comparator configured to generate a pulse signal based on two output differential signals from two differential outputs of the active RC filter, a buffer, and a digital processing module, the cut-off frequency of the pulse signal is proportional to the RC product of the active RC filter; the buffer is configured to generate two input differential signals going to the two differential input ends of the active RC filter based on the pulse signal; the digital processing module is configured to count the number of cycles of the pulse signal in a preset time length; and on the basis of the cycle number of the pulse signal in the preset time length and a number threshold value corresponding to the preset RC constant, a switch control signal used for controlling on and off of the s