Abstract: A transient voltage difference circuit is coupled into a TTL current sinking output circuit for transient performance enhancement during transition from high to low level potential at the output. The TTL output circuit includes a pulldown transistor element for sinking current from an output node to low potential, a base drive transistor for driving the base of a current sinking pulldown transistor element, an input base node of the base drive transistor coupled to receive input signals of high and low level potential, and a voltage clamp network coupled between the input base node and low potential for maintaining a potential level at the input base node sufficient to turn on the base drive transistor. An RC network is coupled between the input base node and low potential.

Abstract: An emitter follower current switch circuit is provided for emitter coupled logic or current mode logic (ECL/CML) circuits having output buffer emitter follower transistor elements which source true and complementary output signals of high and low potential to respective true and complementary outputs of the ECL/CML gate. The emitter follower current switch circuit effectively disconnects the output current sink from and ECL/CML gate output and corresponding output buffer emitter follower transistor element when the corresponding output is at high potential. At each output a current switch transistor element is coupled between the respective output buffer emitter follower transistor element and the output current sink. A control circuit controls the conducting state of the current switch transistor element so that it is on (conducting) or off (non-conducting) for corresponding output signals of low and high potential respectively.