A transistor amplifier must have a DC biasing circuit for several reasons. Especially, we will need two separate voltage supply to provide the desired class bias voltage to the emitter-collector and emitter-base. In fact it is actually only done in certain applications, but found that biasing voltage can be obtained separately from a single supply. Second, the transistor is very sensitive to temperature and creates a condition called thermal runaway. Thermal runaway will quickly destroy the bipolar transistor, because the collector current out of control quickly and will improve to the level of damage and the temperature will rise if there is no stabilizing the temperature at the amplifier to eliminate this effect. A common class for refractive surgery is a Class A, AB, B, and C. All of these classes use the same arrangement of the components to her on the operation of the DC bias transistor Q-point or different. Location of the variation bias point Q for different amplifier classes Cl...