Advantages and disadvantages of positive and negative input

We choose to see the difference between positive phase amplification and reverse phase amplification:

1. The input impedance of the positive phase amplifier is very high, and the input impedance of the reverse phase amplifier is equal to the input resistance, so the input impedance is much smaller than that of the positive phase amplifier.

2. The two input potentials of inverse amplification are always close to zero, only differential mode signal, with strong anti-interference ability; In addition to the differential mode signal, the two inputs of the positive phase amplifier also have a large common mode voltage, and the amplifier must have a high common mode rejection ratio to suppress the common mode voltage.

3. The phase of positive phase amplification output signal is the same as that of input signal, and the phase of reverse phase amplification is opposite.

thus it can be seen

1. The value of the input resistance of the positive phase amplifier does not affect the input impedance, while the input resistance of the inverse amplifier is about equal to the input impedance.

2. When the input impedance is required to be very high, the positive phase amplifier should be selected.

3. If the input impedance is required to be low, either positive phase or reverse phase can be selected. When the phase is not considered, reverse amplification is preferred, because there is only differential mode signal in reverse amplification.

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