ASITIC: Analysis and Simulation of Inductors and Transformers for ICs

In RF circuits, the most important effects tend to be the hardest to simulate, such as passive device modeling, substrate coupling and the package parasitics. Hence designers are forced to be conservative and many times this leads to sub-optimal performance. Also, often designers are reluctant to use passive components at RF frequencies due to a lack of proper modeling and simulation of these structures. ASITIC can help the designer overcome these barriers.

ASITIC is an interactive tool that allows an RF circuit designer to design and simulate spiral inductors and transformers in the IC environment. More generally, ASITIC allows the RF circuit designer to plan and optimize the layout of metal structures, such as capacitors and inductors, in the presence of magnetic and electrical interaction and coupling through the substrate and oxide layers of the IC.

ASITIC works with a mini technology file that describes the substrate and metal layers of the process. Once inside ASITIC, the designer works with as many structures as memory permits. One can obtain s-parameters for inductors/transformers/bond pads/capacitors and use this information for circuit simulation. ASITIC can also be used to obtain broadband circuit models of the structures which can be used in SPICE simulation. The final layout of the design can be saved as a CIF file and imported into layout tools for final fabrication.

Through a combination of design, analysis, and optimization, ASITIC can help the circuit designer to make effective use of inductors and transformers. In addition, ASITIC gives the RF designer a handle on substrate coupling in the IC occurring not only with active devices, but also through large passive devices such as capacitors and inductors.