Basic circuit diagram of TTL inverter

From the previous analysis, it is known that the dynamic performance of the BJT inverter with a resistive load is not ideal. Under the premise of keeping the logical function unchanged, several components can be added to improve its dynamic performance, such as reducing the delay caused by the charge storage effect of the BJT base and the load capacitance. This requires changing the structure of the inverter input circuit and output circuit to form the basic circuit of the TTL inverter. The figure below is a basic circuit of a TTL inverter.

The circuit consists of three parts: the input stage of the circuit is composed
of transistor T1 _; the output stage is composed
of T3 _, T4 _and diode D;
the intermediate stage composed of T2 serves as the driving circuit of the output stage, which converts the single-ended input signal v _{I2 of T2} into complementary double-ended output signals v _I3 and v _I4 to drive _T3 and _T4 .