High PSR Low Drop-Out Regulator With Feed-Forward Ripple Cancellation Technique

A low drop-out (LDO) regulator with a feed-forward ripple cancellation (FFRC) technique is proposed in this paper. The FFRC-LDO achieves a high power-supply rejection (PSR) over a wide frequency range. Complete analysis and design steps of the FFRC-LDO are presented in this paper. Kelvin connection is also used to increase the gain-bandwidth of the LDO allowing for faster transient performance. The LDO is implemented in 0.13 ¿m CMOS technology and achieves a PSR better than - 56 dB up to 10 MHz for load currents up to 25 mA. Load regulation of 1.2 mV for a 25 mA step is measured, and the whole LDO consumes a quiescent current of 50 ¿A with a bandgap reference circuit included. To our knowledge, this is the first LDO that achieves such a high PSR up to 10 MHz.