The invention relates to a large-bandwidth continuous-time common-mode feedback circuit and a design method thereof. The method comprises the following steps of: designing an ideal common-mode
signal; detecting the common-mode value of an operational amplification output
signal through a common-mode detection circuit; comparing the detected common-mode value of the operational amplification output
signal with that of the ideal common-mode signal; after amplifying an
error signal through the common-mode feedback circuit, outputting two common-mode
feedback control signals fed back to the drain
electrode of a biasing tube of an operational amplification biasing circuit so that the whole common-mode feedback circuit forms a single-stage
amplifier to ensure that the common-mode feedback circuit has enough
phase margin; and finally stabilizing the operational-amplified output common-mode point on the ideal common-mode value according to the
negative feedback function of common-mode feedback. The invention overcomes the defects that the traditional continuous-time common-mode feedback circuit is a multi-stage
amplifier and has poor stability, and ensures that the common-mode feedback circuit is a one-stage common-source
cathode-
input amplifier through adjusting the feedback point of the common-mode feedback; and the common-mode feedback circuit has favorable stability and is suitable for large-bandwidth ultrahigh-speed full-differential analog circuits.