Two-stage resistor-capacitor coupling amplifier circuit

Two-stage resistor-capacitor coupling amplifier circuit

 In addition to DC-coupled amplifier circuits, coupling amplifier circuits also come in the form of resistor-capacitor coupled amplifier circuits and transformer-coupled amplifier circuits.
    ①Resistance-capacitance coupling multi-stage amplifier circuit. The figure shows a two-stage resistor-capacitor coupling amplifier circuit. It can be seen from the figure that between two single-stage amplifiers
, the AC signal is transmitted from the first stage to the second stage through the coupling capacitor C2. The "load" of the first stage is the "input resistance" of the second stage
. After the AC signal is amplified by the first stage, it is sent to the second stage by the coupling capacitor cz, and the signal voltage falls on
both ends of the input resistor of the second stage. This is the meaning of resistance-capacitance coupling.
    The resistance-capacitance coupling method has two outstanding advantages - the coupling capacitor has a DC blocking effect, so the working points of the amplifiers at each stage are independent of each other,
which brings great convenience to the design and maintenance of the circuit: second, when the signal frequency has been Under known conditions, appropriately selecting a coupling capacitor with a larger capacity
can reduce the loss of the signal on the capacitor to improve transmission efficiency.
    Disadvantages of the resistance-capacitance coupling method: it cannot amplify signals with very low frequencies. Because, for signals with very low frequency, the capacitive reactance of the coupling capacitor
is very large, and the signal transmission efficiency is too low. The
    resistance-capacitance coupling method is mostly used in small signal amplification circuits of various frequencies .