A Fully Integrated Multi-Phase V oltage Regulator With Flying-Capacitor-Based Inter-Inductor Current Self-Balancing Scheme and Charge-Recycling

Abstract

This article presents a fully integrated voltage regulator (FIVR) featuring a high power density, fast dynamic voltage scaling (DVS), and self-balanced inductor currents. The proposed two-phase 2L1C buck converter topology can 2×reduce the number of power switches and flying capacitors (CF) com- pared to the conventional two-phase three-level (2P3L) converters while inheriting the benefit of a lower switching voltage. The single-CF-based self-balancing of the inductor currents with no extra overhead is a key contribution to this work. For the high scalability of the 2L1C topology, the inter-channel balancing (ICB) scheme is also presented. Moreover, the proposed charge-recycling gate driver is capable of reducing the switching power loss. The proposed two-phase FIVR chip with on-chip spiral inductors of 2 nH was fabricated in a 55-nm CMOS process. The chip operating at 200 MHz/phase showed a 45- V/µs DVS rate and a transient slew rate of 40 mA/ns. The measured power density and the peak efficiency were 0.9 W/mm 2 and 79.1%, respectively. The ICB scheme was demonstrated with the four-phase VR chip able to supply a maximum output power of 2 W.