2. Practical application and working principle of operational amplifiers
The operational amplifier is characterized by low open-loop input impedance, low input noise, low gain, low cost, low precision and high power consumption. Simulate operational amplifiers. According to the flexible use of operational amplifiers, we can achieve the functions we need. Here are a few examples in detail. The basic circuit for the application of operational amplifiers is the proportional circuit which requires the input signal to be scaled up. The proportional circuit is divided into reverse proportion circuit, same proportion circuit, different ratio circuit, etc. The following is the same proportion circuits. The same proportional circuit is shown in figure 1, which is essentially the same as the reverse scale circuit, except that the same one is the reverse input on the grounding part.
The relationship between its output voltage and input voltage is:
As long as the ratio coefficient changes, the output voltage can be changed, and the Ui is same direction as U0, and the same ratio circuit is higher than required for the common mode suppression of the integrated transport. The basic circuits of operational amplifiers have sum/difference circuits, integral circuits and differential circuits, logarithmic and exponential computing circuits. More detailed examples are not followed here. Logarithmic and exponential operations, as well as proportion, sum and difference computing circuits, can make up multiplicative or division computing circuits and other nonlinear computing circuits.
Application of operational amplifier: passive filter circuits
The function of the filter circuit: allow the signal within the specified range to pass; the signal beyond the scope of the regulation cannot be passed.
Classification of filter circuit:
Low pass filter: allows low frequency signal to pass and decay high-frequency signal;
High pass filter: allow high frequency signal to pass and decay low-frequency signal;
Band pass filter: allows the signal to be passed within a certain band range and decay the signal without the band;
Band rejection filter: prevents signal within a band from passing, and allows the signal to decay without the band;