A Monolithic 30uA – 1.5A > 85%-Efficiency, Passive-Ramp-Extended-Ton Controlled Buck Converter For Mobile SoC Fast DVS

In this paper a 2uA quiescent current, passive-ramp (PSR) extended-Ton controlled buck converter IC is proposed for modern mobile silicon-on-chip (SoC) for a longer battery lifetime. From the small signal analysis, the proposed modulation scheme only needs a simple integrator error amplifier for regulation. With so, the trans conduction Gm of type-I integrator can be scaled with the output integrating capacitor and the operating current. Conversely, reducing the quiescent current of the error amplifier sacrifices the transient response especially for the dynamic voltage scaling, which is highly related to the slew rate of the error amplifier. A dynamic biased operational transconductance amplifier with unlimited output current is adopted to solve this issue and halves the settling time. The chip prototype is designed using a TSMC O.18um CMOS process. The post-layout simulation results show a 4MHz switching frequency, 2uA quiescent current, and a loading range from 30uA to 1.5A with > 85% efficiency. The load transient shows an 110m V undershoot voltages with a 1.5A/I00ns current step.