This paper presents an output-capacitorless low-dropout voltage regulator implemented in a commercial 90nm CMOS technology for low-voltage applications. The power efficiency is enhanced by significantly reducing its dropout voltage and quiescent current. The resultant degradation of its transient performance is tackled by a switched-capacitor circuit. The regulator operates under 1V supply achieving power efficiency of about 90% under the full-load condition. When a 100mA load current step with 5ns rise/fall time is applied, the output voltage variations are within 10% of the steady-state value. Monte Carlo and temperature-sweep simulations show the robustness to process and temperature variations and device mismatches.