NEED HELP IN designing a class A amplifier


Joined Feb 28, 2011
Q1 is used as a voltage amplifier. It's output impedance in that design is 1K. While the voltage was amplified, it will not drive much of a load. The power stage are set in an emitter follower configuration. It amplifies current but no voltage. In this particular setup, the base current necessary to drive the final output Q3, is more than the output of Q1 can provide. So Q2 is added in conjunction to Q3 in a Darlington setup to amplify the current many times more, lookup Darlington for more info. The beta of the Q3 transistor is increased
C3 is a DC blocking cap allowing the coupling of the initial voltage amp to the power amp back section.