Consider the op-amp difference amplifier in Figure 9.24(a). Let \(R_{1}=R_{3}\) and \(R_{2}=R_{4}\). A load resistor \(R_{L}=10 \mathrm{k} \Omega\) is connected from the output terminal to ground.

(a) Design the circuit such that the difference voltage gain is \(A_{d}=15\) and the minimum difference input resistance is \(30 \mathrm{k} \Omega\).

(b) If the load current is \(i_{L}=0.25 \mathrm{~mA}\), what is the differential input voltage \(\left(v_{I 2}-v_{I 1}\right)\) ?

(c) If \(v_{I 1}=1.5 \mathrm{~V}\) and \(v_{I 2}=1.2 \mathrm{~V}\), determine \(i_{L}\).

(d) If \(i_{L}=0.5 \mathrm{~mA}\) when \(v_{I 2}=2.0 \mathrm{~V}\), determine \(v_{I 1}\).

Figure 9.24(a):-

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R R ww 20 WW R3 RA (a)