NON-QUASI-STATIC EFFECTS IN ADVANCED HIGH-SPEED BIPOLAR CIRCUITS

This paper presents a detailed study on the non-quasi-static (NQS) eff ects in advanced high-speed bipolar circuits. An NQS Gummel-Poon compa tible lumped circuit model, which accounts for carrier propagation del ays across various quasi-neutral regions in bipolar devices, is implem ented in the ASTAP circuit simulator. The effects are then evaluated a nd compared with the conventional Gummel-Poon model for the emitter-co upled logic (ECL) circuit, non-threshold-logic (NTL) circuit, and vari ous advanced circuits utilizing active-pull-down schemes. For the ECL circuit, the effect decreases with reduced power level and increased l oading. For the NTL circuit, due to its front-end configuration, the e ffect is more significant than that for the ECL circuit but tends to i ncrease with reduced power level. As the passive resistors (and the as sociated parasitic RC effect) are decoupled from the delay path and th e circuit delay is made more intimately related to the intrinsic speed of the devices in various advanced active-pull-down circuits, the del ay degradation due to NQS effect becomes more significant.