Single- versus Double-layer Spiral Inductor on High-Resistivity Trap-Rich Silicon Substrate

On-chip spiral inductors are indispensable components in modern integrated circuits (ICs), enabling critical functions across wireless communication, power management, and emerging technologies. This paper presents a comparative analysis of single- and double-layer square spiral inductors in terms of self-inductance, quality factor and resonant frequency, both fabricated on a high-resistivity trap-rich silicon substrate to minimize substrate losses and improve electrical performance. Electromagnetic simulations using ADS software, together with experimental measurements, show that the double-layer inductor achieves a 34.6% increase in self-inductance compared to its single-layer counterpart. However, the single-layer design outperforms the other in terms of quality factor (29.43% decrease) and resonant frequency (62.9% decrease) due to lower resistance and parasitic capacitance in its structure. By balancing the performance trade-offs for specific applications, using calibrated ADS simulations, these results help in selecting the optimal inductor design.