Q4. a) With the aid of sketches, explain the concepts of the negative and positive feedback. b) Figure 4 shows a non-inverting amplifier, which can be viewed as an open- loop op-amp connected to a feedback network. Identify the type of feedback connection of Figure 4 and show the reason. Given that R₁ = 20 kn, R₂ = 380 kn, and the open-loop gain of the op-amp in Figure 4 is A, = 10000, determine the closed loop gain, A+ = vo/v₂, of this feedback amplifier. V₁ R₁ R₂ Figure 4: Non-inverting op-amp

Assume that the R2/R1 ratio of a feedback amplifier with voltage supply of +/- 10 V  is 3.0 and that a value of 1.0 V is applied to the non inverting input of the op-amp. What is the output voltage value?

3A

Analogue 2

An operational-amplifier circuit that may be used as a controller is shown in Figure Qla. (a) R4 ww R1 R3 e Co Figure Qla R1, R2, R3 and R4 are resistors and C1 and C2 are capacitors. Assume both op-amps are ideal and their input/output voltages are ei, e and eo, as shown in the Figure. Using the impedance approach: (i) obtain the transfer function for each op-amp, i.e. E(s)/E:(s) and Eo(s)/E(s). (ii) hence obtain the complete transfer function for the system, i.e. Eo(s)/Ei(s). (iii) Determine D(s) = Eo(s)/E:(s) when R1 = R2 = R3 = R4 = 1 N and C1=1 F, C2= 2 F. %3D (b) Consider the closed-loop control system shown in Figure Qlb. 1 Σ K.D(s) (s +2) Figure Qlb K is the gain and D(s) is the transfer function obtained in part (a)-iii. (i) Plot open loop zeros and poles for the above system in the s-plane. [. Determine whether the point (-1+j) is a closed loop pole for any value of K, by considering the angle criterion at this point. (ii) (c) Briefly summarise the steps, which need to be…

a) Two feedback configurations are shown in Figures Q1.a(i) and Q1.a(ii). Derive the closed-loop gain Af in each case. V₁. V₁. A1 B1 Figure Q1.a(i) A₁ B₁ Figure Q1.a(ii) A₂ A₂ B₂ ܘܢ -V

4. (a) Determine the input and output impedances of the amplifier in Figure - 2. The op-amp datasheet gives ZIN = 1.2 MQ, ZoUT = 120 Q, and AOL = 150,000. (b) Find the closed-loop voltage gain. Department of Computer & Network Engineering, College of Computer Science & Information Technology Vin Vout R 240 k.N R; 10 kN Figure - 2