Feedback circuit of transistor amplifier 2

So positive feedback amplifiers are commonly used in simple receivers with low quality requirements. Although negative feedback circuits can weaken the input signal of the amplifier and reduce its gain, they can also reduce distortion and improve the stability of the amplifier. Therefore, adding some negative feedback appropriately can significantly improve the quality of the amplifier.diode  A high-performance amplifier or radio often uses various forms of negative feedback circuits. (1) There are various forms of negative feedback circuits, but based on the relationship between the negative feedback signal and the output signal, negative feedback can be divided into two types: voltage negative feedback and current negative feedback. Voltage negative feedback: If the negative feedback voltage u is directly proportional to the output voltage u, then this type of negative feedback is called voltage negative feedback. Figure 5-52 shows the connection of voltage negative feedback.diode  The feedback network of voltage negative feedback is connected in parallel with the output circuit of the amplifier, so it will reduce the output impedance of the amplifier. Current negative feedback: If the negative feedback voltage u is proportional to the output current i, diode then this type of negative feedback is called current negative feedback. Figure 5-53 shows the connection of current negative feedback. The feedback network of current negative feedback is connected in series with the output circuit of the amplifier, so it will increase the output impedance of the amplifier.diode