Analogue Electronics Assignment-

Question 1 -

Fig. 1 is a two stage amplifier with feedback. The source V_s has no dc component. Details of the small signal model parameters for the BJTs are given in the information sheet on pages 2-3.

(a) Identify the type of feedback topology employed in the amplifier of fig. 1. How would the feedback topology change if the output voltage were taken from the emitter node of Q2 rather than the collector node?

(b) Find the dc voltages at all nodes and the dc currents of Q1 and Q2.

(c) Draw the open loop amplifier circuit taking into account the loading effect of the feedback network.

(d) Determine the β of the feedback network.

(e) Hence, calculate the mid-band open loop gain of the amplifier.

(f) Determine the closed loop mid-band voltage gain (V_o/V_s) of the amplifier.

(g) Calculate the input and output resistances of the closed loop amplifier at mid-band.

(h) Output resistance seen at the output node, V_o.

(i) Estimate the bandwidth of the overall amplifier by calculating the upper 3dB frequency. [Hint: First calculate the upper 3dB of the open loop amplifier, then apply feedback theory]

Question 2 -

The circuit shown in Figure 2 is a pulse generator.

(a) In the quiescent state (i.e., before the trigger pulse is applied), find V₂, V_o, and V₁ assuming all diodes (including zeners) are ideal.

(b) At time t = 0 a narrow, positive, trigger pulse V_t whose magnitude exceeds V_R is applied. At t = 0⁺, find Vc (Voltage across the capacitor) and V₁.  {Hint: remember that the voltage across the capacitor cannot change instantaneously}

(c) Plot the waveform V_o and V_i as a function of time. Demonstrate that the circuit behaves as a monostable multivibrator with a pulse width T (to be derived later).

(d) Find V_o and V₁ at t = T⁺ and continue the waveforms until the steady state is reached. What is the recovery time constant? Is the diode ON or OFF?

(e) Show that T is given by T = RCln(2V_o/V_R).

Attachment:- Assignment File.rar