Schottky transistor

A saturated transistor is turned on hard, which means that it has a lot more base drive than it needs for the collector current it is drawing.

Storage time accounts for a significant portion of the propagation delay in the original TTL logic family.

Storage time can be eliminated and propagation delay can be reduced by keeping the switching transistors from saturating.

As the transistor comes close to saturating, the Schottky diode conducts and shunts any excess base drive to the collector.

In 1956, Richard Baker described some discrete diode clamp circuits to keep transistors from saturating.

His patent also showed how the Schottky transistor could be used in DTL circuits and improve the switching speed of saturated logic designs, such as the Schottky-TTL, at a low cost.