Capacitors are essential in DC biasing of transistors and co

Capacitors are essential in DC biasing of transistors and connecting the input and output to amplifiers. See the figure as an example for a BJT amplifier. [Please be succinct, no more than 100 words for each (c) and (d). Keep it clean, if I cannot read I cannot give you points] Explain the purpose of the coupling capacitors (for example C_1 and C_2 in the figure) Discuss how the amplifier circuit would be affected if we do not have capacitors available for the circuit implementation. Explain the function of the Emitter (or source) resistance and the bypass capacitor that is in parallel to this resistance.

Solution

Couling capacitors shows differnce in AC and DC analysis. capacitor short for ac analysis and open for DC analsis. If there is no coupling capacitors, when doing DC analysis the load resistor is also included in DC analysis, which decreases the output voltage and the base is connected to ac ground, which produces 0 V at the base of the transistor. So, the transistor will not turn ON.

Bypass capacitor is very useful in ac analysis. It shorts the emitter resistance in ac analysis as it is parallel to emitter resistance to increase the gain of the amplifier. It opens at dc analysis and short at ac analysis. It decides the effect of emitter resistance.