Modeling and optimization of magnetic core TSV-inductor for on-chip DC-DC converter

Abstract

Conventional on-chip spiral inductor consumes significant top metal routing area, thereby preventing its popularity in many on-chip applications. Recently TSV-inductor with a magnetic core has been proved to be a viable option for on-chip DC-DC converter in a 14nm test chip. The operating conditions of such inductors play a major role in maximizing the performance and efficiency of the DC-DC converter. However, due to its unique TSV-structure, unlike conventional spiral inductor, much of the modeling details remain unclear. This paper analyzes the modeling details of a magnetic core TSV-inductor and proposes a design methodology to optimize power losses of the inductor. With this methodology, designers can ensure fast and reliable inductor optimization for on-chip applications. Experimental results show that the optimized magnetic core TSV-inductor can achieve inductance density improvement of 6.0--7.7X and quality factor improvements of 1.3--1.6X while maintaining the same footprint.