Resistor–transistor logic (RTL) is a class of digital circuits built from bipolar junction transistors (BJT), and resistors; it is the earliest transistorized digital logic used. It is called resistor–transistor logic because the logic gating function (e.g. AND) is performed by a resistor network and the amplifying function is performed by a transistor (contrast this with DTL and TTL). Its main limitation was its limited fan-in, 3 inputs being the limit for many circuit designs, before it completely lost usable noise immunity. It has a small low noise margin. A detailed treatment with applications is found in the RTL Cookbook by Donald Lancaster.
See also
- Diode–transistor logic (DTL)
- Transistor–transistor logic (TTL)
- Emitter-coupled logic (ECL)
- Integrated injection logic (I2L)
