A wide-load-range high-frequency high-PSR output-capacitorless LDO with adaptive negative capacitance

This paper presents a wide-load-range, high-frequency, high power-supply rejection (PSR) output-capacitorless low-dropout regulator (OCL-LDO) for high-speed optical communication chips. It proposes a load-current-adaptive negative capacitance (NCC) compensation technique to overcome the difficulty of maintaining high-frequency PSR enhancement over a wide load range. By sensing load current and tuning the feedback network, the adaptive negative capacitance (ANCC) circuit dynamically scales the amplifier gain and equivalent negative capacitance, compensating pass-transistor gate parasitics and supply-ripple coupling. Implemented in 0.18 μm CMOS, post-layout simulations show 0.1-50 mA operation. For loads above 10 mA, PSR remains below -67 dB at 100 kHz and -45 dB at 1 MHz, reaching -74 dB and -88 dB at 50 mA.