RC circuit can generally be used for filtering, phase shifting, feedback, acceleration, pulse shaping, differential circuit, integral circuit and other functions.
The value of each component has a great influence on the circuit characteristics. For example, if the upper resistance is large, it can be considered that the lower resistance is mainly connected in parallel by capacitors, and if the lower resistance is large, it is mainly connected in parallel by capacitors. If there is little difference between the two resistors, it can be considered as a capacitor with two resistors in parallel (the power supply is generally considered as a short circuit to AC). For DC, these two resistors are voltage dividing resistors; For alternating current, two resistors are connected in parallel with the capacitor. If the resistance is large, the capacitance is basically the filtering or AC feedback path at the middle end.