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This brief presents an ultralow quiescent class-AB error amplifier (ERR AMP) of low dropout (LDO) and a slew-rate (SR) enhancement circuit to minimize compensation capacitance and speed up transient response designed in the 0.11-μm 1-poly 6-metal CMOS process. In order to increase the current capability with a low standby quiescent current under large-signal operation, the proposed scheme has a class-AB-operation operational transconductance amplifier (OTA) that acts as an ERR AMP. As a result, the new OTA achieved a higher dc gain and faster settling time than conventional OTAs, demonstrating a dc gain improvement of 15.8 dB and a settling time six times faster than that of a conventional OTA. The proposed additional SR enhancement circuit improved the response based on voltage-spike detection when the voltage dramatically changed at the output node.