Amplifier circuit is the most basic one of the circuit is very important, why is it basically it? It is essentially ubiquitous, whether integrated or discrete circuit chip, the amplifier circuit is everywhere. It is important that if there is no amplification circuits, electronic circuit is basically unable to move.
Amplifying circuit from the beginning to now have undergone age tubes, transistors and integrated circuits in three stages. Small when we saw a large glass tube amplifier that tube, now gone; amp discrete components can now be seen, but less and less; more and more integrated chips amplifying circuit, a small chip, for example PAM8403, 3DG6 and also about the same size, but the completion of the preamplifier, the power amplifier, muting, filtering, and many other functions.
But no matter how complex integrated circuits, but also by a simple amplification circuit, so today we learn the hardware, but also need to understand the basic amplification circuit.
Usually an amplifier circuit is current amplification and voltage amplification. The so-called amplification, is the magnitude of the input voltage and current of the amplification, such as 10mV input voltage, the output of 1V, the voltage which is amplified. Usually the pre-amplifying circuit for voltage, current amplification is generally used for power amplification. For example, our sensors collect signals are relatively weak, the voltage is converted into very small, basically microvolts millivolts, it is necessary to enlarge the first voltage, the amplification also need to be filtered, static noise, and finally a current amplification circuit driving end.
Basic amplifying circuit is the transistor amplifier, including the common base, common emitter, common-collector amplifier. Three kinds of circuits are common, more common base in the high frequency amplification, low frequency cascode preamplifier of more, is generally used in a common-collector current amplification or power amplification.
Learning about the amplifier circuit, the theory is not clear if the individual is recommended, by experiments, three kinds of structures multisim or proteus actual circuit, keep in mind some typical parameters, in particular to maintain the static working point of the resistance of the resistor, typically a voltage test point value, input and output current, magnification and the like. For some complex theoretical derivation, but also to prove that these outputs, if we can understand the best, so you can easily design and debug.
Finally, tell us about the common transistor, such as 901x series, 8050,13xxx series, specific parameters can refer to the data described.
