4. (35 points) The amplifier of Fig. 4 consists of two identical common-emitter amplifiers connected in cascade. Observe that the input resistance of the second stage, Rin2, constitutes the load

resistance of the first stage. (a) For Vcc = 10 V, Rị = 90 kohms, R2 = 35 kohms , RE = 4.5 kohms, Rc=7.5 kohms, and ß = 100, VBE = 0.7V, Vr = 25 mV, determine the dc collector current and dc collector voltage of eachtransistor. (b) Draw the small-signal equivalent circuit of the entire amplifier and give the values of allits components (ignore ro). \text { (c) Find } R_{i n 1} \text { and } v_{b} / v_{v i g} \text { for } R_{s i g}=3 \mathbf{k} \Omega \text { (d) Find } R_{i n} 2 \text { and } v_{b} / v_{b 1} \text { (c) For } R_{L}=2.3 \mathrm{k} \Omega \text {, find } v_{d} / v_{b} 2 \text { (f) Find the overall voltage gain } v d v_{\text {sig. }} \text {. } (a) Considering Fig. 4, perform a SPICE simulation using LTSPICE (or equivalent) of 2-stageamp (DC, AC and Transient). Utilize Q 2N3904 (npn BJT) model and all capacitors C =2.2 um. Attach the schematic or netlist to your exam sheets. Probe Vin, Voutl, and Vou2 vs time. Include screenshots of simulation results for the circuit to your exam sheets. (c) For frequency domain simulation, obtain plot of dB gain magnitude versus frequency for the complete amplifier. What is simulated amplifier bandwidth? Include screenshots of simulation results for the circuit to your exam sheets.