A capacitor-free CMOS low-dropout regulator with damping-factor-control frequency compensation

A 1.5-V 100-mA capacitor-free CMOS low-dropout regulator (LDO) for system-on-chip applications to reduce board space and external pins is presented. By utilizing damping-factor-control frequency compensation on the advanced LDO structure, the proposed LDO provides high stability, as well as fast line and load transient responses, even in capacitor-free operation. The proposed LDO has been implemented in a commercial 0.6-μm CMOS technology, and the active chip area is 568 μm×541 μm. The total error of the output voltage due to line and load variations is less than ±0.25%, and the temperature coefficient is 38 ppm/°C. Moreover, the output voltage can recover within 2 μs for full load-current changes. The power-supply rejection ratio at 1 MHz is -30 dB, and the output noise spectral densities at 100 Hz and 100 kHz are 1.8 and 0.38 μV//spl radic/Hz, respectively.