Modeling and measurement of substrate coupling in Si-bipolar IC's up to 40 GHz

Parasitic substrate coupling can severely degrade the performance of high-speed ICs and must be considered carefully in circuit design. Therefore, this paper proposes several equivalent circuits that are well suited for modeling substrate coupling up to very high frequencies with standard circuit simulators such as SPICE. Their element values can be calculated for arbitrary layout configurations from numerical simulations (using our SUbstrate SImulator SUSI), which are based on experimentally determined, specific technological/electrical data. The validity of both the simulator and the equivalent circuits has been verified by on-wafer measurements up to 40 GHz, the highest frequency reported so far for modeling of substrate coupling. For this, special test structures were designed and fabricated in an advanced Si-bipolar technology. This work is focused on substrate modeling in very-high-speed rather than in complex ICs.