Contents
What is the use of transistor-transistor logic?
Transistor-transistor logic (TTL) is a class of integrated circuits which maintain logic states and achieve switching with the help of bipolar transistors. One of the prominent features of transistor-transistor logic signals is the ability of the inputs of the gate rise to the logical “1” if left unconnected.
What is an input transistor?
A transistor has two inputs, called gate and source, and one output, called drain. The gate input is drawn connected to a plate that is parallel to the plate connecting source to drain.
Which transistors are the emitters of a TTL inputs?
A two input standard TTL NAND gate is a multiple emitter transistor for the inputs A and B. the output transistors Q3 and Q4 form a totem-pole output arrangement. Operation: If A or B is low, the base-emitter junction of Q1 is forward biased and its base-collector junction is reverse biased.
What is a TTL input?
Transistor-transistor logic (TTL) is a digital logic design in which bipolar transistor s act on direct-current pulses. A TTL device employs transistor s with multiple emitters in gates having more than one input.
What kind of logic does a transistor have?
Transistor-Transistor Logic belongs to the digital logic family. It consists of transistors at both input and output side, diodes and few resistors. Unlike Resistor-transistor logic and Diode transistor logic, both the logic function and amplifying function are performed by the transistors.
Where does the input come from in a TTL circuit?
The input to a TTL circuit is always through the emitter (s) of the input transistor, which exhibits a low input resistance.
How does a TTL NAND gate work in a transistor?
A 2-input TTL NAND Gate with a Totem Pole Output Stage In the TTL NAND gate of Figure 1, applying a logic ‘1’ input voltage to both emitter inputs of T1 reverse-biases both base-emitter junctions, causing current to flow through R1 into the base of T2, which is driven into saturation.
Where is the pull up resistor on a TTL circuit?
Most TTL circuits, however, use a totem pole output circuit, which replaces the pull-up resistor with a Vcc-side transistor sitting on top of the GND-side output transistor. The emitter of the Vcc-side transistor (whose collector is tied to Vcc) is connected to the collector of the GND-side transistor (whose emitter is grounded) by a diode.