Power amplifier is a weak system with high sensitivity, it is easy to accept a number of external and 55 datasheet and internal irregular signals, that is, the input of the amplifier circuit, the output side there are still some random variation of voltage or current output, use an oscilloscope or speakers can be aware of. This is the power amplifier voltage noise or interference. The impact of noise common noise factor Nf expressed in units of decibels (dB), Nf the smaller the better, Nf = input signal to noise ratio to steal the signal to noise ratio. Transistor noise sources there are three kinds: (1) thermal noise: As the carrier irregular thermal motion of the body through the resistance of the semiconductor tube sometimes produce; (2) shot Noise: commonly referred to as the transistors current is...