An integrated four-phase buck converter delivering 1A/mm² with 700ps controller delay and network-on-chip load in 45-nm SOI

Abstract

Abstract-We present a four-phase integrated buck converter in 45nm SOI technology. The controller uses unlatched pulse-width modulation (PWM) with nonlinear gain to provide both stable small-signal dynamics and fast response (~700ps) to large input and output transients. This fast control approach reduces the required output capacitance by 5X in comparison to a controller with latched PWM at similar operating point. The converter switches at 80MHz and delivers 1A/mm 2 at 83% efficiency and 0.66 conversion ratio.

Recovery Act: Integrated DC-DC Conversion for Energy-Efficient Multicore Processors

“…Higher switching frequencies allow lower inductor values. Recent work has demonstrated that switching frequencies in excess of 100 MHz can be used in cutting-edge CMOS processes while still achieving efficiencies approaching 90% [10][11][12][13]. However, to achieve efficiencies greater than 90%, switching frequencies are still limited to ~100MHz as shown in Fig.…”

A Switched-Inductor Integrated Voltage Regulator With Nonlinear Feedback and Network-on-Chip Load in 45 nm SOI

“…Planar spiral or other inductor topologies that can be constructed using the interconnects of a typical CMOS process are too resistive to provide efficient on-chip power conversion at reasonable current densities [16]. The efficient use of surface mount technology (SMT) air-core inductors, which can provide a current density up to A/mm [17], has been successfully demonstrated [9]- [13]. However, the size and discrete nature of these devices hinders the scalability of any IVR incorporating discrete SMT inductors.…”

A 2.5D integrated voltage regulator using coupled-magnetic-core inductors on silicon interposer delivering 10.8A/mm²

“…This work presents an early prototype switched-inductor IVR using 2.5D chip stacking for inductor integration. , while the bridge output voltage for each phase, V BRIDGE , drives another RC filter to generate the inner feedback voltage, V FB,I [3]. The pole in both RC low-pass filters is chosen to be below f s so that the steady state amplitude of V REF, I and V FB,I is around 150mV, which gives a small signal feedback gain of ~30V/V and ensures stable loop dynamics.…”

“…In the event of a large load current transient, the error in the output voltage, V OUT , will couple across C FB onto V FB,I and the comparator will react immediately to reduce overshoot in V OUT . This fast non-linear response can reduce the required decoupling capacitance on the output voltage [3]. Also residing on the IC is a 64-tile network-on-chip (NoC) consisting of four parallel, heterogeneous, physical network planes with independent frequency domains.…”

“…Effective implementation of DVFS requires voltage regulators that can provide many independent power supplies and can transition power supply levels on nanosecond timescales, which is not possible with modern board-level voltage regulator modules (VRMs) [1]. Switched-inductor integrated voltage regulators (IVRs) can enable effective implementation of DVFS, eliminating the need for separate VRMs and reducing power distribution network (PDN) impedance requirements by performing dc-dc conversion close to the load while supporting high peak current densities [2][3]. The primary obstacle facing development of IVRs is integration of suitable power inductors.…”