Turn-on transient imposed extrinsic base consideration in BiNMOS transistors

A detailed two-dimensional numerical simulation study on the bipolar devices in the BiCMOS circuit environment during turn-on transient is presented. The unique charge build-up and removal phenomenon in the bipolar device determines the switching speed of the BiNMOS devices. The tradeoffs in designing the extrinsic base in terms of the switching behavior are described. It is shown that the structure with the extrinsic base p+ area farthest from the intrinsic base area has the best switching speed, owing to the largest overshoot in the base voltage initially and the lateral base effects