An improved low dropout regulator (LDO) with high power supply rejection (PSR) over wideband frequency range is presented in this paper. The proposed design employs the supply ripple subtraction and high-pass filtering to achieve high PSR performance. The proposed LDO is fabricated by TSMC 0.35μm 2-poly 4-metal CMOS process. The simulation results for a 50-mA load current show that the PSR is -69 dB at 10 kHz, -59 dB at 100 kHz, -53 dB at 1 MHz, and -58 dB at 10 MHz. The results show that the proposed design is suitable for switching mode DC-DC converter and SoC applications. The active area of the LDO is 270 × 320 μm2.