A TM-APSM SIMO Buck Converter With Ultralow Quiescent Current and Fast-Transient Response for IoT Applications

This letter presents a time-multiplexing adaptive pulse-skip modulation (TM-APSM) single-inductor multiple-output (SIMO) buck converter for Internet of Things (IoT) applications. The converter generates 0.8, 1.2, and 1.8 V independent supply voltages from 2.4-4.2 V battery. The proposed successive approximation frequency modulator (SAFM) improves transient response without extra quiescent current. Also, the implemented ADC-based adaptive on-time (AOT) generator suppresses the output ripple under a wide range of input and output voltages. The chip fabricated in the 55-nm CMOS process achieves 93.2% peak efficiency within 0.3 \muA to 12 mA total load range. It consumes only 33 nA quiescent current and achieves 150 \mus output recovery time at 0-to-4 mA load transition. A decent efficiency of 70% is also obtained under 3 \muA ultralight load condition.