Analog circuit design(amplifier with BJT) with abstraction(model)
When you cascade the amplifiers, the net input impedance will the input impedance of the first stage and the net output impedance will be simply equal to the output impedance of the last stage. What needs to be taken care of are the central impedance or the impedance between any two stages. You need to make sure that the output impedance of one stage should be equal to the input impedance of the next stage. Mismatch of impedance can cause lot of power loss and your output signal may be weak.