A Low-Power High-Gain Low-Dropout Regulator for Implantable Biomedical Applications

This paper presents an ultra-low-power and high-gain low-dropout (LDO) regulator. It is based on the flipped voltage follower cell with an adaptive biasing technique that is suitable for implantable biomedical applications. The error amplifier for the proposed regulator consists of two cross-coupled common-gate cells and a pseudo-folded-cascode structure to increase the regulator’s loop gain. In addition, three different compensation techniques including Miller, cascode, and Q-reduction are simultaneously utilized at the LDO regulator to achieve high stability despite having the minimum load current and ultra-low power consumption. The proposed LDO regulator has been simulated in TSMC 90-nm CMOS technology with minimum power consumption of 2.8 µW at no load. Post-layout simulation results show that the proposed LDO regulator is stable over load currents from 30 µA to 40 mA with a maximum on-chip CL of 100 pF. Moreover, the voltage regulator settles in less than 850 ns at 0.75 V output voltage that is achieved in response to a load transient step of 40 mA with a rise time of 200 ns. Besides, the obtained line and load regulations are significantly improved to 1 mV/V and 36 µV/mA, respectively.