Voltage control circuit and method

The invention provides a voltage control circuit and method. The circuit comprises a P input end, a P output end, an N input end, an N output end, a first active component group, a second active component group, a virtual current source and control units. The P input end comprises two passive components RP1 and RP2 which are connected in parallel, and the P input end is connected to the P output end through RP2; the N input end includes two passive components RN1 and RN2 which are connected in parallel, and the N input end is connected to the N output end through RN2; the first active component group is connected to the P input end through RP1; the second active component group is connected to the N input end through RN1; the virtual current source is connected in series with the first active component group or the second active component group; the control units are disposed at the N input end and the P input end and used for adjusting values of the passive components to offset commonmode voltage on the circ