Response to the following problem:
In this problem we investigate the effect of the inevitable variability of β on the realized gain of the CE amplifier. For this purpose, use the overall gain expression in Eq.
where R? L = RL RC. Consider the case R_ L = 10 kΩ and Rsig = 10 kΩ, and let the BJT be biased at IC = 1 mA. The BJT has a nominal β of 100.
(a) What is the nominal value of / Gv / ?
(b) If β can be anywhere between 50 and 50, what is the corresponding range of / Gv/ ?
(c) If in a particular design, it is required to maintain / Gv /within ± 20% of its nominal value, what is the maximum allowable range of β?
(d) If it is not possible to restrict β to the range found in (c), and the designer has to contend with β in the range 50 to 150, what value of bias current IC would result in /Gv / falling in a range of± 20%of a new nominal value? What is the nominal value of Gv in this ase?