Question

Consider the circuit shown in Fig. 1. If 𝑉1 = 10V; the BJT has a β = 200 and 𝐼𝑠 = 10 𝑎𝐴 and the capacitors are short circuits in the frequency range of operation, determine the values of 𝑅1 and 𝑅2, if the amplifier is to have a gain of 100. What is its’ operating point ? It is given that 𝑅3 = 100 Ω.

Answer 1

$r_s=V/I_s=10/10=1\ \Omega$

input resistance:

$R_{in}=\beta r_s=200\ \Omega$

$gain=I_{out}/I_{in}$

$1/R=1/R_1+1/R_2+1/R_3$

When a line is drawn joining the saturation and cut off points, such a line can be called as Load line. This line, when drawn over the output characteristic curve, makes contact at a point called as Operating point.