The total switch time of bipolar integrated injected logic (I 2 L) is simulated. The simulations are carried out at three different current levels: 0.1, 1, and 10 μA. For each current the Ge fraction in the base is varied from 0 to 20%. It is shown that the introduction of Ge in the base makes it possible to reduce the amount of current needed to switch the transistor at a desired speed. At least 90% of the original current can be saved by using a well-designed SiGe heterojunction bipolar transistor instead of a likewise well-designed homojunction bipolar Si transistor. The necessity to reduce the amount of current used per computation is one of the most important problems that needs to be solved before evolution towards higher computational speed and the development of hand-held equipment can progress. Therefore, the possibility to save 90% of the current makes SiGe HBT an interesting device for future digital bipolar technology.