Concept : To demonstrate the working of BJT as a Inverter

Explanation:

A Bipolar Junction Transistor (BJT) inverter switch is a simple yet fundamental application of a transistor in digital electronics, acting as a basic switch to invert a logic signal. It is a crucial building block in logic circuits, allowing for signal amplification and switching.

A BJT has three terminals: the collector (C), base (B), and emitter (E). The operation of a BJT as a switch relies on controlling the base current (Ib​), which in turn controls the larger collector current (Ic​).

• NPN BJT: In an NPN transistor, when a small current flows into the base, it allows a larger current to flow from the collector to the emitter.

• PNP BJT: In a PNP transistor, the current flows out of the base, allowing current to flow from the emitter to the collector.

Simulation Mode: Transient

Simulation Parameters: .tran 0.1m 10m 0 

Reference Netlist:

* BJT Inverter Switch

.model mybjt NPN

R1 COM.1 COM.2 1k 

Q1 0 COM.3 COM.2 mybjt 

V1 COM.4 0 PULSE(0 5 0 1u 1u 1m 2m 0.0 ) 

R2 COM.3 COM.4 1k 

V2 COM.1 0 DC 5 

.tran 1m 10m 0 

.control 

run 

plot all 

.endc 

.end

Reference Circuit Schematic:

Make the circuit diagram with the exact pin-to-pin connection as shown below to practice. This will help you to complete the experiment successfully.

Reference Circuit Details:

• Supply Voltage=COM.1
• Input Voltage=COM.4
• Output Voltage=COM.3

Reference Output:

After the simulation is done, the following output graph appears at the screen showing the voltages and currents across all the nodes.

Conclusion:

The output demonstrates the working of a BJT  inverter where the output is exactly the inverted form of the input. The output can be further smoothened in case of a CMOS inverter.

Assignment:

Implement the same circuit using a PNP transistor.

< Exp 4. Parallel RLC Resonance                 up                   Exp 6. Positive Diode Clipper >