Design a feedback amplifier to supply a current to an LED. Use the configuration shown in Figure 12.27 where \(R_{L}\) is replaced by the LED.

(a) Assuming an ideal op-amp is available, design the circuit such that the diode current is \(I_{O}=3 \times 10^{-3} V_{i}\) where \(V_{i}\) is in the range 0 to \(5 \mathrm{~V}\).

(b) If \(V_{i}=5 \mathrm{~V}\), what is the error in diode current if the op-amp has a finite gain of \(A_{g}=10^{3} \mathrm{~mA} / \mathrm{V}\) and \(h_{F E}=80 ?\)

Transcribed Image Text:

+ + VE 1 Vcc RL + Vfb RE Figure 12.27