Unveiling the Marvels of Amplifiers: Exploring the Intricate World of Operational Amplifiers (Op-Amps)

  Amplifier is an extraordinary electronic component that can amplify input voltage by thousands of times. It is commonly known as an operational amplifier or op-amp, initially used for analog computation circuits involving addition, subtraction, differentiation, and integration. This is its circuit symbol (Figure 1).

While the circuit symbol appears simple, its internal structure is highly complex. The classic 741 op-amp might appear overwhelming, but don’t worry. Even if we don’t fully understand it, we can effortlessly apply it to create marvelous things. Let’s now provide a brief explanation of its internal structure and the function of each component. Just the input section alone involves numerous components. These components together form a differential amplifier, resulting in a high input impedance and enhanced circuit immunity to interference.

The input impedance of the differential amplifier can be considered infinite, meaning this part can be approximated as an infinitely large resistor. This design feature ensures no impact on the input signal.

For instance, if the input signal is 1 volt with an impedance of 1000 ohms, having a low input impedance in the amplifier, let’s say 100 ohms, would reduce the signal to 0.09 volts, causing significant deviation. Thus, it is crucial to maintain a high input impedance. When the resistance is 1 million ohms, the voltage at the amplifier input becomes close to 0.99 volts, which is almost the same as the 1-volt input. Therefore, higher input impedance is desirable. In contrast, the output impedance of the amplifier is exceptionally low, maximizing the output current.