The invention relates to a low-
voltage operational amplifier for reducing
system offset
voltage, which comprises a folded
cascode input module (101), a CLASSAB output-stage
control circuit (102) and an output-stage module (103), and solves the problems of large
system offset
voltage, inaccurate output-stage quiescent current control, waste of dynamic
power consumption and the like in the existing low-voltage CLASSAB
operational amplifier. An output stage quiescent current error caused by a
channel length modulation effect is improved, meanwhile, a second stage common-gate tube is added, the current matching of the first stage common-source common-gate tube is improved, the
input offset voltage of the
operational amplifier system is effectively reduced, and when large pull-sink current exists outside,
current limiting is carried out on the CLASSAB output stage
control circuit (102), so that the output stage quiescent current error caused by the
channel length modulation effect is reduced. Compared with the prior art, the CLASSAB output-stage operational
amplifier has the advantages that the internal maximum
power consumption is limited, the heating value is reduced, the useless
power consumption is reduced, and the application range of the CLASSAB output-stage operational
amplifier in a low-voltage and high-precision circuit system is widened.