1. What is Feedback? Chaeyoung is an engineer who is building a communication sy
ID: 2293072 • Letter: 1
Question
1. What is Feedback? Chaeyoung is an engineer who is building a communication system. She wants to reduce the effect of noise from unwanted nearby signals by using a negative feedback circuit, which is shown in Figure 1. Assume that the op amp is ideal, and ? ? 00 for the transistor. Vcc Re Figure 1: Tzuyu's negative feedback circuit (a) What is the quantity being sampled i.e. what is the output quantity): voltage or cunt 0.5 pt (b) What is the quantity being mixed with the input: voltage or current? 0.5 pt (c) From your answers in (a) and (b), what type of feedback topology is being used? 1 pt (d) Recall that the forward gain, A, is the ratio of the output signal (so) to the error signal (se). Express A in terms of Ri and RE. 2 ptsl (e) On the other hand, the feedback factor F is the ratio of the signal being fed back to the input (sfb) to the output sinal (s). Express T in terms of Rt and RE. 2 pts (f) Given your answers in (d) and (e), what is the closed loop gain, AcL? 2 ptslExplanation / Answer
The solution to this problem is given below:
(a). Here in this circuit the emitter current is the sampled quantity. So, current is the sampled quantity.
(b). Voltage drop across resistor R?E? is the quantity that is being mixed. So, voltage is being the mixed quantity.
(c). Since, current is the sampled quantity and voltage is the mixed quantity, the feedback topology is transconductance. So, the circuit is of transconductance amplifier (output/input gives the dimention of 1/Resistance).
(d). Since the Opamp is of ideal type and the circuit is of open loop type, gain of the opamp (A) is infinite.
As per the guideline, first 4 subparts have been answered. Hope this detailed explanation helps.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.