A High-Efficiency Capacitor-Less LDO with Adaptive Dynamic Range Extension for Biosensing Applications

This paper introduces an on-chip capacitor-less Low Dropout Regulator (LDO) with dynamic range extension that targets low-power biosensing applications. A current load Dynamic Range (DR) of 1850x is achieved through a 4uA-7.4mA implementation while also maintaining high current efficiency over all current load conditions. The improvement in DR due to the adaptive extender presented in this paper is 6.17x greater than the LDO without the extension circuit. This is made possible through very low-overhead circuitry that adaptively senses the load current and dynamically modifies current in the LDO buffer stage to extend operating headroom of the LDO. The LDO also achieves high Power Supply Rejection Ratio (PSRR) across the varying current range while remaining stable across the 1850x load variation. It exhibits superior current efficiency and a very low total quiescent current consumption of 438nA at the low-load condition. The additional current draw of the dynamic sensing circuitry kicks in at higher load current conditions and has a very minimal impact on overall efficiency (>99% at full-load).