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Learn the Basic Knowledge of Operational Amplifier (1)

1. There is a balancing resistance in general anti-phase/phase amplification circuit. What is the role of this equilibrium resistance?
(1) Provide a suitable static bias for the transistors inside the chip.

Internal chip circuit is usually coupled directly, and it can automatically adjust the static working point. However, if an input pin is received the power supply or the ground directly, it automatically adjust function is not normal, because the inside of the chip transistor can't push up ground voltage and lower power supply voltage, which leads to the chip can't meet the virtual short and virtual broken conditions, needing additional circuit analysis.

(2) Eliminate the influence of static base current on the output voltage, the size should be in balance with the equivalent resistance value of the external DC channel in the input terminal, which is also the reason for its name.

2. What is the function of the same phase proportional operation amplifier in the feedback resistor and a capacitor?
(1) The feedback resistor and capacitor form a high-pass filter, and the local high frequency amplification is particularly severe.
(2) Prevent self-excitation.

3. What is the consequence of the operational amplifier and the phase amplifier circuit if it is not connected to the equilibrium resistance?

(1) Burn the operational amplifier, which can damage the transport and release, and the resistance can play a role of partial pressure.

4. Overview of operational amplifier operation:
The circuit of the operational amplifier consists of a wide range of circuits, which are confusing. When it analyzes the operation principle of the operational amplifier without grasping the core, it often makes the headache. This paper collects the application circuit of the transport circuit and hopes to gain after the reading.

However, before analyzing each circuit, it is important to recall the two skills that must be taught in the teaching materials, namely "virtual short" and "virtual broken".
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