Q: If the input signal is systematically referenced, must the capacitive coupling be added? I am actually testing, either positive, inverting input, operation is not working.
A: The capacitive coupling is isolated from the DC component, and the non-work may be caused by no static working point. AC Signal amplification Circuit or audio amplification circuit, you can also use a power bias circuit, the static DC output voltage is reduced to half the supply voltage, based on a single supply operation, but the input and output signals need to add AC coupling capacitance.
The General op amp works with dual power supplies with the ((v+) + (v))/2=0v as the reference voltage, and the OP amp works in the middle of the linear zone. If the op amp is operated on a single supply, the voltage reference point should still be set at ((v+)-0V)/2= (v+)/2. In the case of an inverting amplifier, the reference voltage of the phase input should be set to V+/2, and the input signal of the inverting input should be V+/2 as the reference point. When the input signal is close to 0V or v+, the op amp works in a non-linear region, and the amplifier output is saturated or cut-off distortion.
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Hardware 100,000 Why--op release Chapter (11) About single-supply op amp Application