DIFFERENTIAL AMPLIFIER: A differential amplifier built using two NPN BJTs. It is powered by a dual ±20 V supply and uses matched resistors for symmetry. The circuit amplifies the difference between two input signals—one at 1 kHz and the other at 2 kHz—while rejecting any common-mode signals. The shared emitter resistor (100 Ω) provides negative feedback, improving linearity and stability. Differential amplifiers like this are commonly used in analog signal processing @and the input stages of op-

This simulation shows the working of a differential amplifier. The yellow and green waveforms are the two input signals applied to the circuit, and the violet waveform is the output. The amplifier responds to the difference between the two inputs, rejecting the common part and amplifying only the variation between them. As seen in the graph, the output (violet) is a scaled version of the difference of the two input signals, which is the key feature of a differential amplifier used in signal cond