14 9 4 Transistor as an Amplifier CE Configuration To

Last updated: 6/10/2023

14 9 4 Transistor as an Amplifier CE Configuration To operate the transistor as an amplifier it is necessary to fix its operating point somewhere in the middle of its active region If we fix the value of V corresponding to a point in the middle of the linear part of the transfer curve then the de base current I would be constant and corresponding Vec 1 R collector current I will also be constant The de voltage V would also remain constant The operating values of Vand determine the operating point of the amplifier CE If a small sinusoidal voltage with amplitude is superposed on the de base bias by connecting the source of that signal in series with the BB Supply then the base current will have sinusoidal variations superimposed on the value of n As a consequence the collector current V also will have sinusoidal variations superimposed on the value of Ic producing in turn corresponding change in the value of Vo We can measure the ac variations across the input and output terminals by blocking the de voltages by large capacitors E Re Vcc RE 14 32 A simple circuit of a CE transistor amplifier Vo In the discription of the amplifier given above we have not considered any ac signal In general amplifiers are used to amplify alternating signals Now let us superimpose an ac input signalu to be amplified on the bias V de as shown in Fig 14 32 The BB output is taken between the collector and