Physics- and process-based bipolar transistor modeling for integrated circuit design

TLDR

Circuit designers must optimize transistor configurations to meet high‑speed, low‑noise, and low‑power specifications, yet existing tools lack efficient generation of the many model parameters required for bipolar compact models, a gap that also stems from underappreciated modeling and extraction challenges. The paper proposes a physics‑ and process‑based approach that enables rapid, consistent generation of bipolar model parameters during early process development, thereby reducing extraction effort. The method is implemented in the TRADICA CAD tool, which integrates with circuit simulators and exposes only emitter size and the numbers of emitter, base, and collector contacts as the designer‑visible parameters. The approach enables rapid exploration of process options and alignment of process development with circuit product requirements.

Abstract

Many applications require circuits to be operated close to the performance limits of current silicon (production) processes to meet the required circuit specifications for, e.g., high speed, low noise, and low power consumption. Therefore, the circuits must be carefully optimized by selecting the individual transistor configurations. As a consequence, model parameters for a large variety of configurations (100 or more) are often requested. Unfortunately, most present design tools and modeling methods do not support an efficient generation of the respective parameter sets for bipolar compact models. This paper describes an approach that is physics and process based; facilitates an extremely fast generation of consistent model parameter sets, even during the initial phase of process development; and reduces parameter extraction efforts significantly. This allows one to quickly explore various process options in advance and to align process development with circuit product requirements. The approach is supported by a computer-aided-design tool named TRADICA, which can be combined with circuit simulators allowing the emitter size and number of emitter, base, and collector contacts to be the only model parameters visible to designers. Related modeling and parameter extraction issues are also discussed because these areas are often unknown and tend to be underestimated by circuit designers and process developers but have a significant impact on the flexibility, capability, and accuracy of circuit design.