Question

Consider the circuit shown in the figure below:


The feedback factor ${}^{\prime }{\beta }^{\prime }$ for the above circuit is equal to
(Assume the op-amp to be ideal).

• A. $0.33k\Omega$
• B. $1.33k\Omega$
• C. $6k\Omega$
• D. $2k\Omega$

Answer 1

The correct option is B $1.33k\Omega$


$\begin{array}{cc}\beta & =\frac{V_f}{I_0}\\ \text{now,}{V}_f& =I_2\times 4k\Omega \\ I_2& =\frac{I_0\times \left(3k\Omega \right)}{(3+2+4)k\Omega }\\ I_2& =\frac{I_0}{3}\\ \therefore V_f& =\left(\frac{4}{3}k\Omega \right)I_0\\ \beta & =\frac{V_f}{I_0}=\frac{4}{3}\times {10}^3=1.33k\Omega \end{array}$