The invention discloses a loop circuit compensating circuit which comprises an
operational amplifier (OPA), a p-channel
metal oxide semiconductor (PMOS)
pipe (P1), a
capacitor (C), an n-channel
metal oxide semiconductor (NMOS)
pipe (N3), and an n-channel
metal oxide semiconductor (NMOS)
pipe (N1), wherein the negative input end of the OPA is connected with a reference
voltage, the positive input end of the OPA is connected to the ground through a
resistor R2, the output end of the OPA is connected with a grid
electrode of the PMOS pipe (P1), a source
electrode of the PMOS pipe (P1) is connected with a power source, a drain
electrode of the PMOS pipe (P1) is connected to the ground through a
resistor R1 and the
resistor R2, the positive end of the C is connected with the grid electrode of the PMOS pipe (P1), the negative end of the C is connected with a source electrode of a NMOS pipe (N2), a source electrode of the NMOS pipe (N1) is connected with a source electrode of the NMOS pipe (N2) and then is connected to the ground, the source electrode of the NMOS pipe (N1) is connected with a grid electrode of the NMOS pipe (N2), a drain electrode of the NMOS pipe (N1) is connected with a configuration input bias current (IBIAS), substrates of the NMOS pipe (N1), the NMOS pipe (N2) and the NMOS pipe (N3) are connected with to the ground. The source electrode of the NMOS pipe (N3) is connected with the drain electrode of the NMOS pipe (N2) through a NMOS pipe (Nb), an drain electrode of the NMOS pipe (Nb) is connected with source electrode of the NMOS pipe (N3), a source electrode of the NMOS pipe (Nb) is connected with the drain electrode of the NMOS pipe (N2), and an grid electrode of the NMOS pipe (Nb) is connected with a bias
voltage (VBIA), and a substrate of the NMOS pipe (Nb) is connected to the ground. The loop circuit compensating circuit can reduce a
capacitance valve and a
layout area on the premise that additional
power consumption does not increased, and the fact that a
phase margin and a
gain margin are not changed is guaranteed.