Inductorless voltage regulator system with voltage increasing capability for low-power sensors

This paper presents an integrated inductorless regulator that is able to create a nominal 3.6 V output voltage from two different supply voltage ranges namely from 3 V to 3.6 V and from 4.5 V to 5.5 V. This is made possible by the parallel use of CP based regulator for lower supply voltages and linear regulator for higher supply voltages to increase the current efficiency. The attenuation of supply noise is in both supply voltage ranges better than 43.5 dB. The regulator is able to operate with load currents of 0.6 mA - 1.3 mA while the current efficiency can be up to 92.6 % with the line and load regulations of 1.4 mV/V and 2.1 mV/mA. The required reference voltage is generated with a two bit tunable bandgap voltage reference with accuracy up to 23 ppm/°C and output noise of 5.6 μV_rms on a 500 Hz bandwidth. The output noise of the system is 100.9 μV_rms on a 500 Hz bandwidth according to transient noise simulation. The circuit was designed with 0.35 μm CMOS.