Single-Ended vs. Differential Amplifiers

Most often than not, the signal from the sensor in a measurement and control or monitoring system is very small (one millivolt or less) and a key step in signal conditioning is amplification. Therefore, the sensor is often connected to the input terminals of an amplifier. The amplifier in this case can either be single-ended input or differential input type.

In a single-ended input amplifier, one of its input terminals is grounded as demonstrated in Figure 1.0 below and the output is the gain constant A times the input voltage:

For an amplifier with a differential input, it has non-inverting and inverting input terminals as illustrated in the figure below and ideally in this case, neither of the amplifier input is grounded and the output is the differential gain A_d times the difference between the input voltages.

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