Question 1 [12 points] Consider a two-stage BJT amplifier as shown in the Figure 1 below. The first stage is a common-emitter amplifier configuration while the second stage is an emitter-follower. Manufacturer's transistor data sheet specifies that hfe = 200, hie = 5 k2, hoe = 10 μS. Hence, we can deduce that r = hie = 5 kn, ro = 1/hoe = 100 k2, and ẞhre = 200. = 33k 4.7µF Tri 15 V 0.47 F 6.2k 500 22k 18k- www 15 V 33k T12 4.7 F Pa T12 Trl 6.2k 5001 Figure 1. A two-stage BJT amplifier. Figure 2. A directly-coupled BJT amplifier. (a) Determine the bias point of the amplifier circuit shown in Figure 1 (i.e., dc biasing parameters for transistors Tri and Tr2). [3 points] (b) Determine the ac amplifier parameters of the amplifier circuit depicted in Figure 1 (i.e., overall amplifier gain and lower cut-off frequencies). [3 points] (c) Next consider a modified circuit where the transistor Tr2 will be directly biased from transistor Tr1 (see Figure 2) by removing the bias resistors 18 k2 and 22 k2 and the coupling capacitor 0.47 uF in between two amplifier stages. Find the bias point and the ac amplifier parameters of the modified circuit. Discuss the advantages and disadvantages of this modified circuit (Figure 2) with respect to the original circuit (Figure 1). [4 points] (d) Discuss the impact (both advantages and disadvantages) of adding a bypass capacitor across the 5002 emitter resistor. Briefly justify your answer. [2 points]