A simple differential amplifier circuit design

Differential amplifier circuits (subtractors)

A differential amplifier is generally used to input multiple signals and output the difference between them. It is often used to amplify differential mode signals and to suppress common mode signals.

A simple differential amplifier circuit is shown in the diagram below: (Figure 1)

When designing a subtractive circuit, special attention needs to be paid to the need to reduce the bulk of the in-phase amplification. It is then necessary to use a voltage divider circuit, such as the voltage divider resistor network in Figure 1 which makes the signal at the in-phase input attenuated by half. If no attenuation is carried out (Figure 2), then the circuit is equivalent to 2x amplification at the in-phase input and -1x amplification for the inverted phase, and then the output is equivalent to twice the in-phase input minus the inverted input.

Figure 2

Simulation results.

Figure 1 Simulation results

From the results it can be seen that

meets the design requirements.

Figure 2 Simulation results

From the results it can be seen that

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