Question

Draw a simple circuit of a CE transistor amplifier. Explain its working. Show that the voltage gain, A_V, of the amplifier is given by A_V = (β_acR_L/r_i), Where β_ac is the current gain, R_L the load resistance and r₁, is the input resistance of the transistor. What is the significance of the negative sign in the expression for the voltage gain ?

Answer 1

For diagram see L.A.T.Q. 4 (c)

When an nc input signal, V, ir superimposed on the bias V_BB, the output, which is measured between collector and ground, increases

The negative sing 4 in the expression shows that the output,voltage and input voltage have phase difference of π,