Design Methodologies for 3D Mixed Signal Integrated Circuits: a Practical 12-bit SAR ADC Design Case

Three-dimensional (3D) integration technology has been proposed as a promising technology to provide small footprint, reduced wirelength, and the capability of heterogeneous integration. In particular, 3D IC is a good candidate to address the design issues in conventional analog/digital mixed-signal IC designs. In this work, we focus on modeling and analyzing the impacts of through silicon vias (TSVs) on mixed-signal ICs. Based on the analysis, a set of design methodologies for 3D mixed-signal ICs are proposed. The design methodologies are verified with a case study, in which a 12-bit successive approximation register analog-to-digital converter (SAR ADC) is re-designed by partitioning it into three stacked layers for 3D integration. The experimental results show that, compared to the traditional 2D counterpart, our 3D SAR ADC with optimized TSV placement can achieve significant area and power reduction, and performance improvement. Specifically, due to the isolation of substrate noise disturbance in our 3D design, the signal-to-noise-plus-distortion ratio (SNDR) is improved from 68.74 dB to 74.12 dB.