Diode–transistor logic

In electronics, DTL is the abbreviation for the logic family, " Diode Transistor Logic".

This technique of digital electronic circuits was developed in the early 1960s (RTL) as a successor to the resistor -transistor logic.

Logic gates and logic functions were implemented by the combination of diodes in the entrance and subsequent amplification of the signal by logic transistors. Compared to RTL, this results in a higher processing speed and lower power consumption.

Design and function

The adjacent circuit shows the structure of a NAND gate in DTL technique. If the input diodes V1 and V2 block (inputs to high potential ), the current through the resistor R2 which forms a voltage divider with the resistor R1 flows. In this way, the increased voltage on the base of the transistor V5 leads to the switching of the transistor. Thus, the output goes to low level. This corresponds to a positive logic NAND gate. Since the transistor goes into saturation, to obtain a high level of gate delay time due to the necessary removal of the barrier layer. DTL circuits are therefore no longer used. The logic level of the circuit layers at typically about 0 to 1 V for the low level and at about 1.7 V to 5 V for the high level.

New Logic

The DTL family has now been superceded in the circuit development and was practically no importance by newer logic families.

As a direct further development of the diode transistor logic, transistor-transistor logic (TTL), may be considered with the various sub-families. The slow fail-safe logic ( LSL) has been developed for use in environments with particularly strong electrical interference. Furthermore, there is the emitter-coupled logic ( ECL) for fast applications. These three technologies are all based on bipolar transistors.

In addition, there is the complementary MOS logic ( CMOS logic ) as a new logic family in the CMOS technology with the use of field-effect transistors available.

• Digital technology