A Low Quiescent Current Asynchronous Digital-LDO With PLL-Modulated Fast-DVS Power Management in 40 nm SoC for MIPS Performance Improvement

A low quiescent current asynchronous digital- LDO (D-LDO) regulator integrated with a phase-locked loop (PLL)-modulated switching regulator (SWR) that achieves the near-optimum power management supply for core processor in system-on-chip (SoC). The parallel connection of the asynchronous D-LDO regulator and the ripple-based control SWR can accomplish fast-DVS (F-DVS) operation as well as high power conversion efficiency. The asynchronous D-LDO regulator controlled by bidirectional asynchronous wave pipeline realizes the F-DVS operation, which guarantees high million instructions per second (MIPS) performance of the core processor under distinct tasks. The use of a ripple-based control SWR operating with a leading phase amplifier ensures fast response and stable operation without the need for large equivalent-series-resistance, thus reducing the output voltage ripple for the enhancement of supply quality. The fabricated chip occupies 1.04 ${\rm mm}^{2}$ in 40 nm CMOS technology. Experimental results show that a 94% peak efficiency with a voltage tracking speed of 7.5 ${\rm V}/\mu{\rm s}$ as well as the improved MIPS performance by 5.6 times was achieved.