Ultra-fast Cap-less LDO for Dual Lane USB in 28FDSOI

Abstract

A fully on-chip LDO for very fast load transient up to 15mA/nsec in 28nm FDSOI is presented. Proposed LDO capitalizes on technological boost given to on-chip capacitance density and MOS current drives to implement conventional compensation technique without using off-chip capacitor. Dominant output pole enables the LDO to achieve its superior load transient performance. Proposed LDO generates 1.0V output from a 1.6V input supply and has maximum output current capacity of 15mA. Simulated worst case PSR at 10kHz is-23dB and current efficiency is 93% at maximum load condition. Three such LDOs are combined to provide dedicated 1.0V supplies to dual lane USB cores and their PLL. Area including reference generator, three LDO and all on-chip capacitances is 0.2mm2.