Electromigration-aware and IR-Drop avoidance routing in analog multiport terminal structures

Abstract

This paper describes an electromigration-aware and IR-Drop avoidance routing approach considering multiport multiterminal (MP/MT) signal nets of analog integrated circuits (IC). The effects of current densities and temperature in the interconnects may cause the malfunction/failure of a circuit due to IR-Drop or electromigration (EM). These become increasingly more relevant with the ongoing reduction of circuit sizes caused by the evolution of the nanoscale integration processes. Therefore, EM and IR-Drop effects must be taken into account in the design of both power networks and signal wires of analog and mixed-signal ICs, to make their impact on the circuits' reliability negligible. In previous EM and IR-Drop-aware analog IC routing approaches, `dot-models' are assumed for the terminals, i.e., each terminal has only one port that need to be routed, however, in practice, analog standard cells usually contain multiple electrically-equivalent locations, often distributed over different fabrications layers, where legal connections can be made, i.e., MP terminals, which need to be properly explored. The design flow is detailed, and the applicability of the approach is demonstrated with experimental results, and also, by generating the routing of an analog circuit structure for the UMC 130 nm design process.